EF36 PW 1965 12
User Manual: EF36
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PRACTICAL WIRELESS December, 1965
AÇO LL
SOLDERING INSTRUMENTS
AND EQUIPMENT
DESIGNED FOR
THE AMATEUR'S
RADIO STATION
ILLUSTRATED
List No. 70 e" BIT
IN
PROTECTIVE
SHIELD
List No. 68
for catalogue apply direct to:-
Sales and Service Dept.
ADCOLA PRODUCTS LTD.,
ADCOLA HOUSE,
GAUDEN ROAD, LONDON, S.W.4
Telephones Telegrams
MACaulay 4272 & 3101 SOLJOINT LONDON SW4
NOMBREX INSTRUMENTATION
TRANSISTORISED AUDIO GENERATOR
Model 63 LI7.I.9
* Laboratory Specification 10 C s to 100 Kc s.
* Direct Calibration. * Si ìe and square output.
Also available:
* INDUCTANCE BRIDGE 66 E18. 6.9
* POWER SUPPLY UNIT 61 E6.14.6
* C.R. BRIDGE 62 ... E8.11.9
* R.F. SIGNAL GENERATOR 27 ... £9.I6.9
All prices include Battery. Post and Packing.
Prompt delivery
S.A.E. for Technical Trade and Export
Leaflets enquiries invited
NOMBREX LTD. Phone: 3515
Estuary House, Camperdown Ter., Exmouth, Devon
JACKSON
the big name in PRECISION components
MINIATURE TUNING CAPACITORS
TYPE "00"
The Jackson 'O' range
contains six basic types of
different air -dielectric
tuning capacitors with a
wide variation of capacities
available in each type. In
addition, there are optional
extras such as concentric -
spindle slow- motion drives,
built -in trimmers and
plastic covers. The
maximum capacitance per
section ranges from 12, 18
420 pF for AM types. or 24 pF for FM types to
Type 00 subminiature twin capacitor at 12/6
Type OFM two -gang for FM at 1 I t-
A Type OPC for printed circuit mounting at 14t-
Type OG2 with internal reduction gearing at 16f-
MADE IN ENGLAND
Write for literature
JACKSON BROS. (LONDON) LTD.
(Dept. P.W.) KINGSWAY -WADDON, CROYDON,
SURREY
Phone: Croydon 2754 -5 Grams: WalfiIco, Souphone, London
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 641
lit b vs HIGHEST QUALITY- -
COMPARE OUR PRICES
GUARANTEE NEW
air e In 125 urtMonths
0p122q
Mouths TYPES
MOST MOLLARD 12in. £2 dui
. 0.0 . 0.0 KW 31/74
MAZDA COSSOR. 14in. £2.10.0 £3.10.0 £3.15.0
EMITRON. EMI -
SCOPE, BRIMAR. 15 -17in. £3. 5.0 £4. 5.0
FERRANTITYPES 19in. £3. 5.0 £4. 5.0
PROCESSED IN
OUR OWN 21 in. £3.15.0 £5.15.0
FACTORY 23in. £3.15.0 £5.15.0
SATISFACTION GUARANTEED
MW 36/24
£4.15.0
CRM 172
MW 43/64
£6.0.0
Autochangers, etc
LATEST GARRARD
All Factory Fresh. All with cartridge.
SRP10 Mono (Single) Player. 04.19.0.
SP25 Semi -Transcription (Single),
211.19.0. AUTOSLIM Standard Auto,
25.19.0. ATO Auto (Limited Number),
58.19.0. ATO Blimiine- elmilar to
ATO, 17.16.0. Model 1,000 -Compact
low- priced record changer, automati-
cally playing up to 10 records, 18.19.0.
Model 2,000- Automatic record chan-
ger with large turntable, playing up to
e records, 07.19.0. Model 8.000 -
Designed for use with high- compliance
cartridges; low -mass arm gives
exceptionally low record wear,
10.10..0. ATOO- Automatic or
manual operation, has precision arm -
bias compensator and heavy turn -
table. 111,19,0. A70 -For the critical
user-offers automatic playing, with
pusher -platform, and many other
features, 019.19.0. LAB80 -An out-
standing automatic araoecription torn -
table for professional reproduction.
MS. 301- Transcription Heavy
Table, 182. 401- Trammiptiop
turntable with heavy 121, turntable,
machine -cut strobe, neon lamp and
speed control, 129.19.0. Model 50-
Automatic record changer with large
Constable, weight -counterbalanced
arm and plug -in pick -up head, 19.10.0.
B.B.B.
0U7- Single Deck Complete, 14.6,0.
UA74 or U25 -Auto Changer. 85.15.0.
PRICES SLASHED
LZ27 TAPE RECORDERS. Famous
make, latest Silver /Grey finish, 4 in-
puts, 2 -speed 35 a 74in. Complete
with microphone, footage counter,
volume level indicator, tone control,
spare spool. This machine takes 71n
spools and Is a full size Recorder, not
Wpi
1800OPrlce n órmally £17.10.0
TEARWCEIYER TYPE RT88.
The very latest Silver /Black finish.
They gave fantastic performance
with reliability, long telescopic aerial,
crystal controlled- Note licence V
required to transmit. They compare
with much dearer mod - £8.19.0
MEMO CALL, 8/8 ocket sized battery
operated tape recorder, complete with
tape, earphone, built -In speaker
Normally 212.10.0. A most for those
who want to record telephone con-
versations, Ideas, letters etc. whilst
Unveiling or 2/6 om £8.10.0
TELEPHONE AMPLIFIER. "Desk
Companion ". A larger model com-
plete with pen and holder etc. Fully
portable and tramletorieed. A most
for the desk leaving both hands free
to deal with papers, £3.10.0
etc., etc. 2/8 PP
56 WATT GUITAR SPEAKERS.
Very heavy coned 121e., cast chassis.
There Y nothing to touch R for
power handling and quality at the
price. Plus ti /- pap. £4.19.0
RINATONE 10- TRANSISTOR, All
wave set, complete with telescopic
aerial, earphone, leathercase, medium
alas. superb performance. Not to be
eenlu.ed with `heap £10.19.0
..C., amazing value.
MULTI- METERS. TK.20.A. 8
Ranges AC/DC/Current/Res. 6
Aff
(stance 0 -100K, moving coil. X9.7 {I
EP.10.K. 10,000 OPV, High quality.
15 Ranges AC /DC /Current /Resist.-
ance, Accuracy 13 %. £3.19.6
EP.20.K. 20,000 OPV, more e
rive version of EP.10. fí4.19.6
EP.30.K. 30,000 OPV, 10 Ranges,
including Resistance to 6
£6.19.
10 Meg. V V
EP.50.K, Professional Quality, 22
Ranges, AC/DC/Volts/Currrent/Res-
ponse /Decibel, /Capaol- £9.19.6
tepee,
PEST EQUIPMENT. IT1 -1 Transis-
torised Signal Injector, complete with
Transistor Oscillator with Indicator
Lamp, Detachable Test
Probe and instructions. 35/-
IDEAL FOR ANY RECORDER.
PRICES SLASHED. GUARANTEED
APPROX. I PRICE. WORLD
FAMOUS MAHR BY ENORMOUS
PURCHASE.
* TAPE *
We offer you fully tene0leed polyester/
mylar and P.V.C. tapes of identical
quality hiS, wide range recording
characteristics ae top grade tapes.
Quality control manufacture. Not
substandard in any way. Try one for
yourself. They are truly worth few
more fioPPers than acetate, sub-
standard, jointed or cheap imports.
Try one and prove It for yourself t
Standard Play Double Play
3' 150ft. 8/8 3' 300ft. 4/-
4' 300fí. 4/6 4 600ft. 8/-
5' 600ft. 7/6 5' 1200ft. 15/-
55' 900ft. 10/6 55' 180ft. 19/8
7' l200ft. 18/6 7' 2400ft. 27/-
Long Play Triple Play
3' 222ft. 2/9 4' 900ft. 13/-
4' 450ft. 5/8 5' 1800ft. 25/-
6' 900ft, 10 /6 51' 2400ft. 84/-
51' 1200ft. 13/- 7' :IMMIX 44/-
7' 100011. 18/8 Quadruple Play
3' 600ft. 8/-
Postage 1/- or Poet Free less 5% on
three reels. Quantity and Trade
enquiries invited.
AM /FM RADIOS
Latest wonderfully styled, guaranteed
top make, 10- transistor with full
long and medium waves. Size 91 x
6s tie z 1212 /rain. Magnificent reproduc-
tion. A pleasure to look at. "An
aristocrat In its class ". 1.2 month
guarantee against faulty Manufacture.
Genuine retad price 7 Gns.
228.7.6. Unrepeatable,
QUALITY PORTABLE
TAPE RECORDER
Fabulous quality and reproduction of
music. 6 transistor, Ilin. and 3Iin.
speeds. Output 500mW into high
quality speaker. Ingenious single
control knob. Fast forward and
rewind. Battery level and record.
level meter. Fast load. Precision
capstan drive with dynamic earpiece
monitor recording. Radio recording
leads. Outside speaker facilities. The
most outstanding portable in the
country. Size 819 /,e x 3i o Olin.
Genuine normal price of 35 gm.
Unrepeatable. 12 month guarantee
All spares available. With I 9Gns.
tape, tape reel, mike, etc.
VALVE IN VALVES GUARANTEED 3 MONTHS
BY RETURN OF POST
satisfaction or Money Hack Guarantee on goods it returned unused within
14 days. ALL t'ALV68 ARE NEW UNLESS OTHERWISE INFORMED.
FREE TRANSIT INSURANCE. POSTAGE 1 valve 6d.. 2-11 1 / -, Free over 12.
OZ4 4/8
1A7GT 9/6
1C5GT 7/6 8L1 9/8
IH5GT 8/9 61.6 7/6
1N5GT 8/9 6L8G 8/8
184 7/8 8L18 7/9
2D21 5/6 61,19 12/8
3A9 4/- 6LD20 7/9
3A5 e/- 6P25 8/6
3D8 9/- 6P28 9/9
3Q4 5/- 6Q7G 4/-
5R40Y 8/- 6Q7GT 8/-
5II40 4/- 83A7 5/9
5Y3G 4/8 6507 4/9
5Y3GT 4/- 68K7 5/-
5Z4 9/- 8SL7GT 5/6
5Z40 7/- 6SN7GT 4/6
5Z4GT 9/8 6SQ7 5/9
8/SOL2 9/- 6D40T 8/-
(USG 7/9 BVBG 4/6
6A70 7/6 MGT 8/-
8AK5 9/3 8%4 4/8
8AQ7 5/- 6%50 5/-
BATB 5/- 8%5GT 5/6
BAIIB 7/- 7B6 9/-
OAVB 6/- 7E7 5/6
OSAS 5/6 705 7/8
55E6 5/6 7C8 7I8
8608G 15/- 7H7 5/-
BBHB 5/- 787 8/9
BBJB 5/- 7Y4 4/6
6BR7 8/8 1051 9/-
6BW8 8/9 1052 14/8
awn 5/- 10F1 4/9
854 2/3 lOLD1114/8
655 5/8 10P18 9/6
656 5/8 10P14 9/8
859 11/- 128E7 7/-
8CD8G 17/- 12AH8 9/-
BDB 8/- 12AT6 6/6
8E1 4/9 12AT7 4/9
6F80 3/6 12AU6 9/-
6E13 4/3 12AU7 4/9
6F14 9/8 12AV8 8/8
6E15 9/812A%7 6/-
8E28 6/6 12BA8 7/-
615G 3/- 12BE6 8/6
6150T 4/3 1213H7 8/9
876 2I6 12E1 17/6
8J7G 4/9 12170T 8/-
63707 7/8 12K70T 4/-
6118GT 6/- 12K8 9/9
6K7 5/9 12K8GT 9/6
6K7G 1/. 12Q7GT 5/-
6K7GT 4/6 125417 8/3
6K8 8/8 128%7 2/9
6H8G 5l- 128Q7 7/6
BKBGT 5/3 1487 14/61EBC41 8/3 EZ41 5/91R19
8825 8/8 19AQ5 7/9 EB581 5/9 EZ80 5/9I8P41
20D1 819 EBF80 7/8 EZ81 6/- SP81
20F2 9/6 EBF89 7/9 FC4 8/- 241
20L1 16/- EBL21 9/9 GZ32 7/0 TDD4
20P1 9/6 EBL31 19/8 HVR2 9/- U14
20P3 11/- EC52 9/9 KT33C 3/9 U18
20P4 17/- ECCS2 4/- KT36 14/- U22
25A80 9/- ECC34 9/-
25L6GT 7/9 ECC40 8/9
25Z4G 7/- E5581 4/9
30E5 e/- E5C82 4/9
80FL1 9/8 ECC83 5/9
30L15 8/9 E5584 7/8
30P4 9/8 ECC85 8/-
30P12 7/- ECC68 9/8
30PL1 9/3 ECF80 8/-
35C5 818 ECF82 8/3
35L6GT 8/- ECH21 11/6
35W4 8/- ECH35 7/8
35Z4GT 5/8 ECH42 8/6
50L6GT 8/6 ECH81 7/-
80 5/- ECRU 8/8
18511T 19/6 ECL80 6/6
185BTA19/6 ECL82 8/-
807(A) 5/- ECL83 10/6
807E 4/9 ECL86 10/3
813 49/- EF36 3/-
888A 12/6 EF39 4/6
854 3/6 EF40 11/-
955 2/3 EF41 8/-
956 2/- EF54 3/3
9001 3/6 EF80 3/6
9002 4/9 EF85 8/-
9003 5/8 KEN 7/6
ATP4 2/8 EF89 6/9
AZ31 6/- EF91 8/-
B38 9l8 EF92 8/-
CBL31 19/- EF183 9/9
CL33 9/- EF184 9/6
C231 7/8 EL32 3/9
DAF91 4/8 EL33 6/6
DAF98 7/3 E1,34 11/6
DF91 3/- EL35 8/-
DF92 3/- EL38 12/8
DF98 7/8 EL41 8/-
DK91 5/6 EL42 7/9
DK9S 7/- EL84 8/6
DK96 7/3 EM34 8/8
DL92 5/- E1280 7/9
DL94 6/6 EM81 6/9
DL98 7/3 E5184 8/9
EABC80 6/6 EM85 8/6
EAF42 3/8 EY51 7/6
EB41 5/- E286 7/3
EB91 2/- E288 8/8
EBC33 4/9 EZ40 6/8
KT44 6/- U24
KT45 8/9 025
KT81 8/0 026
KT73 5/9 U35
KT66 12/- 050
KT78 8/6 U107
KT88 17/6 0191
KTW81 5/9 0281
KTW83 5/- 0282
KTZ63 7/- 0301
MU14 7/-,U329
N37 10/6 U801 19/-
N78 13/- UABC80 7/-
N108 13/- UAF42 7/9
PC86 10)- 0B41 8/8
PC97 7/6!OBC41 7/8
PCC84 8/6 UBC81 6/-
PCC85 8/6 UBF80 7/9
PCC88 11/9 UBF89 7/6
PCC89 8/8 UBL21 9/8
PCCI89 13/6 0CC85 7/8
PCF80 6/9 UCF80 8/6
PCF82 6/- UCH21 9/8
PCF89 12/- IICH42 7/3
PCF88 7/6 OCH81 7/9
PCL82 7/9 0CLS2 8/-
PCL83 9/- 0CL63 10/-
PC1.84 7/3 0F41 8/8
PCL85 7/6 UF42 4/9
PCL88 10/9 UF60 6/3
PERKS 3/9 UF85 7/6
PEN45 8/6IIF89 5/9
PEN48 4/8 01.41 7/6
PL33 8/8IIL44 14/-
PL38 J 9/8 1T1,48 8/3
PL38 17/e 0L84 7/-
PL81 7/9IIR10 7/8
9/6
96 2/3
8/9 7/-
7/6
8/9
12 /8
8/3
126
12/6
8/8
18 /-
12/8 8/6
PLBS 8/8'111a80
PL88 6/eIIII6
PL84 7/8
P231 8/- IIIIB
PY32 10/- U221
PY80 6/6 11Y41
PY81 5/9 IIY85
PY82 5/O VR105
"88 5/9 vai50
PY88 9/-
PY800 6/3 %98
PISO 9/8 Z88
8/9
11 /- 9/8
6/- 5/- 5/- 7/9
7/9
8/6
CONNECTING WIRE
Y.V.C. Bright Colours. Five Y A/m
5ít. coila only.
MAINS
TRANSFORMERS
Excellent Quality Guaranteed Up-
right mounting 250- 0 -250v.
66tnA. 6.3v.. 3A (80mÁ 12/6) e.1 /L`
Ditto set-in-shrouded. .7 V
SPECIAL C.R.T. OFFER
Due to tinge Bulk Special Purchase
we are oHering CRM14l and MW
36/24 Tuhes at the unrepeatable
price of 39/-, P.P. 1216. The above
are guaranteed for 6 mouths.
* BULK BARGAINS
12 POTS. Popular values. 5K. to
2 Meg. (loused, mixed Pro- 4/6
t, long ,p., switch, eta V
CONDENSERS- 25 mixed Electrolytic,
Many popular sizes. List 10/-
Value 15. Our price
100 RESISTORS 6/6
Excellent. sizes l -3 watt.
100 CONDENSERS 9/6
Miniature Ceramic and Silver Mica
Condensers, 3pF to 5,000pF. LIST
VALUE OVER 25.
25 TAG STRIPS 4/-
2, 4, 9, 8-way eta. Unused.
100 HI STABS 9/6
1% to 5 °;, 1íM 0 to 5 m O.
CO -A%, low loss, 6d, yd., 25 yards
11/8; 55 yds. 22/ -; 100 yds. 42/6.
Co -ax Plugs, 1 /8. Wall outlet boxes 8/6
TRANSISTORS
GUARANTEED TOP QUALITY
Huge reduction, Red Spot t6 /
standard LF type now only
White Spot RS 2/-
Mallard Matched Output 1
Kite 0081D and 2-0081 2/6
R.F. Bata 0544, OC45 (2) 1 2/6
3 transistors.
ÁF114 8/- 0044 5/8
AF115 7/8 0545 5/8
AF116 7/8 0072 5/6
AF117 7/- OCR 5/8
ÁF127 9/8 0581D 5/6
0526 12/8 0552 6/-
0C36 14/ -- 0C170 5/8
05171 8/6
GERMANIUM DIODES
General Purpose miniature detector
A.V.C. eta. 8d.
or 8/6 doz.
Gold Bonded highest quality
IndividuaOy tested.
9/8 doz.
SILICON RECTIFIERS
Guaranteed performance. Top
Makes. Tested 250v. working.
100mÁ if 250rA
(3 for 9/8131 (3 for 19/8) 7/6
1/-
LOUDSPEAKERS, 30 Tog Makro
04i, 7/6 5ti.4fn. 8/6
Post( alb. 2/ -, 01b., 1 /e, 7 lb,., 3/8, 151óe, 4/-, etc. (C.O.D. extra). ALL VALVES LESS 5% AND POST FREE IN DOZENS.
Retail Only, BI -Pi Demonstrations. 72 East Street, Southampton
Tel. 26861 11 /12 North Road, Brighton, Tel. 97999
ALL MAIL ORDER AND RETAIL SHOP
350/352 FRATTON RD..;PORTSMOUTH , Tel. 22034
TECHNICAL TRADING CO.
www.americanradiohistory.com
642 PRACTICAL WIRELESS December, 1965
EXCLUSIVE TO YOU ! CONCORD'S TERRIFIC RANGE
TRANSISTOR
POCKET RADIOS
BULK PURCHASE
ENABLES US TO
MAKE THIS FAN-
TASTIC OFFER
-AND WITH
MONEY BACK
GUARANTEE 1 I I
The "SAN REMO"
.. so timed that It
brings the voices of
star entertainers
and vocalists dra-
matically to Bfe-
O N LY 28,6 ein tc uOr n hy ome, 111% 2
1 }m. Fits easily
NO MORE TO PAY into your pocket
or handbag. Works for months off 1/2 battery.
Should last a lifetime, anyone can assemble It in a
hour or two with our easy plan. Miniature
speaker. carrying case--everything only 2816.
2/6 P. & P. (Parts can be bought separately.)
Limited period ---eo rush your order before Its
too late. DEMONSTRATIONS DAILY.
DON'T WALK -
JUST TALK ! !
INTERCOM
OUTFIT &
BABY ALARM
LIMITED QUANTITY SAVE 83.13.1
Robustly made, brand new
current models. You get 2
separate, fully transistorised
intercommunicating sets -
each can speak or listen to
the other - complete with BO ft. connec-
ting wire. Fixed in a flash. Ends baby -
crying worries. Ideal for Workshop to
House. Siokroom, hundred of uses!
Hangs on wall or stands up. Our absurd
price 52/11, battery 2/6 extra. Post, etc.
3/7. Money refunded if not 8 gus. value!
ONLY
5211
MAKE S DIFFERENT
TRANSISTOR RADIOS
FOR
NO EXPER-
IENCE NEC -
, NoSASoldering.
i "4e0 -iv Only 8 con-
-
...op radiooto work.
OB 0 ® Just look, you get
A.B.C. Plans, Cabinet,
Loudspeaker (alone 17/6). Earphone,
4 Semi- conductors, Coils. Condensers,
Resistors, Tuner. Switch. Screws. etc.
YES - EVERYTHING! Loud Clear
English eda ss
pl tEucatí
Educational reception.
Authorities. H.M
Forces, etc. TESTIMONIALS GALORE.
Mr. R. O'D. pt Londonderry, writes: -
/received your components and i must
say that I am very satisfied with them. I have
it already set up!..." COMPLETE HOME/
RADIO plus 3/6 post etc. SEND
IT HAD TO COME EVENTUALLY! THE
"SKYSCRAPER" PERSONAL COMMU-
NICATIONS RECEIVER. Highly sensitive.
World -wide ,short -waves reception including
news in English and countless other broad-
casts from RUSSIA. AMERICA. etc., etc.
Take it anywhere -
it's featherweightl ein.
X 35m. z llin. Band -
spread Tuning, Ver-
nier Dial. Miniature
Valve Circuits, Plug -in
Celle, Own Rod Aerial,
etc. 50% of production
to be exported. Any-
one can assemble it
within 2 hours -only
a few connections to make -experience unnecessary.
Parts incl. Case. Personal phone. Easy -to -follow
plan -49 /6 plus 216 Pat, ete. Ref. G'tee.
TRANSISTOR RADIO KITS
SOLD IN DEPARTMENT STORES AT 35.8.0.
OUR
PRICE
37/6
P. & P.
3/6
Extra d
Well-known brand Trarufetar Radio Kits -YOU
SAVE 23.10.8. Covering all medium /long wave with
parts including Mullard Semi Conductors. 48 page
Instruction manual. Entertaining and educational.
No soldering, Just plug m, making many different
Radios in a few min. Money batik if not delighted.
ONLY
18'6
CAR CIGARETTE
LIGHTER
DISPENSER
High Class Stores sell at
8 pis. -- save £2.4.6
Top quality chromium.
Car cigarette Lighter
-Dispenser. Fixed in a icy -
Pressing Button delivers ready -lit
Cigarette into your hand! Tahoe
10 elgareaa -King size or any size!
As lilted to luxury ears. Safe. fool-
proof. 41 x 4 x lilt. Lifetime
750 only. 8 pins 1/ P.
Refund P. sot (etate worth r812i.).
FABULOUS
ST. TROPEZ MK. 6
The Sensational Pocket Radio
This fantastic offer will amaze you
} v -the beautifully compact ST.
( TROPEZ, measuring 4} x 3 z 1/in.
_ receives
ceives perfectly in bedroom,
office or garden- over all medium
waves including Luxembourg. Un-
ANld. per hour running cost.
YONE can assemble it in one
or two hours using our ample
A.R.C. plan. 26/- (P. & P. 2/6
extra). Case extra Parts can be bought separately.
Read what lust a 15w of our satisfied customers my
R.C. of Harringay writes Received with
thanks Skyroma ... Very pleased. Working
well.
B.M. of Harrogate writes ... I would
like to thank you ... If was a real bargain.
L.S. of London W.8 writes ... given it
a good try out and I am very pleased with
the results.
S.B. of Somerset writes ... delighted
with this radio ... glad if you could send
one mere.
T.F. of Stevenage writes ...1 would just
like to say how pleased my son is with this
radio.
CONCORD ELECTRONICS
IO TRANSISTOR PERFORMANCE
ONLY
55I.
POST 316
LIQUIDATION PURCHASE 500 ONLY
Made to sell at 54 gns. - Save £3.0.6.
Latest camera style radio. Big -Set tone
from tone- chamber moving coil speaker.
new device plucks in Station after Station
including Luxembourg, Caroline, etc.
Fantastic coverage - 187577 metres!
Expensive looking finish, simulated
leather, black and chromium. Size
4)' z 24" x 1}".7 semi-conductors. 55/- +218
batt. +3 /8 P. & P. Refund ff not delighted.
NEW RADIO
VOLKSRADIO
ANYONE
CAN BUILD
IN 2 -3 HOURS
196
EVEN TILE OLDER CHH.DREN
BUILD THEM! ... no soldering -only
16 connections! Then hear it reach out
bringing in station after station, loud and
clear. Palm -oi -hand size 44 x 24 x 1 }in.
Many Testimonials: N.H. of Bradford,
writes: "... I have Just completed one of
your sets successfully. it is the first time I
have ever tackled anything like a radio. and
I must state here and now, I am amazed how
easy it is to a layman like me. Your instruc-
tions and plan have obviously been very care-
fully thought out so that even the most dim
can follow them " Direct from
Manufacturers to You. Send 19 /6
plus 2/6 post, etc.
PARTS AVAILABLE SEPARATELY
AMAZING CIGARETTE
RADIO
ONLY
186
Yes, a perfectly ordinary packet of
cigarettes! - but watch your friends'
astonishment on hearing it fetch in
station after station, loud and clear!
Still hold. 1^ Cigarettes -yet cleverly
conceals highly sensitive, fully transistor-
ised circuit (Including tiny battery).
Even a young boy can assemble it In under
2 hours. No soldering. No experience
necessary. Only 18 connections to make.
Ideal for taking to work with you. From
our bulging testimonial file, Mr. D. B. of
Huddersfield, writes: ". I have fitted
the parts in and tt is working wonder -
odPaseLCnuctors.
A.B.C. Plans. ttc. ONY
18/6 plus 2/6 post etc.
PARTS AVAILABLE SEPARATELY
LTD. (DEPT. P.W.27) 9 WESTERN ROAD, HOVE, SUSSEX
www.americanradiohistory.com
R. .7: C,
December, 1965 PRACTICAL WIRELESS 643
MAIL ORDERS TO:
54 WELLINGTON
STREET, LEEDS I
Terms: C.W.O. or C.O.D. No C.O.D.
under LI. Postage 2/9 extra under L2.
4/6 extra under £5. Trade Supplied.
S.A.E. with all enquiries please.
PERSO NALSHOPPERSWELCOME
AT ANY OF THE BRANCHES
BELOW. OPEN ALL DAY SATUR-
DAY.
BRADFORD 10 No ParaWd
(Half-day rth ed)e ..
Tel. 25349
BRISTOL 14 Lower Castle Street
(Half -day Wednesday)
Tel: 22904.
BIRMINGHAM 30/31 Gt. Western
Arcade, opp. Snow
Hill Station. CENtral 1279. No half -day
DERBV26 Osmaston Rd., The Spot
(Half -day Wed.) Tel: 41361
DARLINGTON Wynd °Half -dayy
Wednesday) Tel: 68043
EDINBURGH 133 Leith Street. d
GLASGOW 326 Argyle Street,
Tel: CITy 4158 (No half -day).
HULL SI Savile Street (Half - wt
Thursday) Tel: 20505
LEICESTER 32 High Street (Half -
day Thurs.) Tel: 56420
LEEDS (County (Mecca) A"`ß
No ) Tel.: 228252
LIVERPOOL day)° CENtral 3573
LONDON 238 Edgware Road W2
(Half-day Thursday)
Tel: PADdingtea I631
1
MANCHESTER
60A -60B Oldham St. Tel: CENtral 2778
(No half -day) New large store.
MIDDLESBROUGH Tri dnesday)
106 Newport Road. Tel: 47096
SHEFFIELD 13 Geheng. Str.«.
Castle Market !lido,
Tel: 20716 (Half -day Thursday) J
VACANCIES FOR STAFF
AT VARIOUS BRANCHES
SHOP EXPERIENCE UNNECESSARY
R.S.C. MAINS TRANSFO
Interleaved and Impregnated. Prim-
aries 200. 230 -250 v. 50 ch. Screened.
TOP SHROUDED DROP THROUGH
/50- 0-250v NmA, 2.3v. 2a, 0- 5 -6.3v. 2a 17/9
350-0-350v SOmA. 6.3v. 2a, 0- 5-6.3v. 2a 21/9
250-0-250v 100mA, 6.3v. 2a, 6.3v. la .. 21/9
250- 0-250v 100mA. 6.3v. 9.5a, C.T. 19/9
250- 0-250v 100mA, 6.3v. 4a. 0- 5 -6.3v. 8a 28/9
300- 0-300v 130mÁ, 6.3 v. 4a, 6.3v.la, for
Muliard 510 Amplifier . 35/9
300- 0-300v 100mA. 6.3v. 4a, 05.6.3v. 3a 28/9
350-0-350v 100mA. 6.3v. 4a, 0- 5-6.3v. 3a 28/9
350- 0-350v 150mA. 6.3v. 4a, 0-5-6.3v. 3a 37/9
FULLY SHROUDED UPRIGHT
250-0-250v 60mA, 6.3v. 2a. 05 -6.3v. 2a
Midget type 21 x 3 x 3f n. 18/9
250-0-250v 100mA. 6.3v. 4a, 0- 5 -6.3V, 3a 29/9
300- 0:300v 100mA, 6.3v. 4a, 5v. 3a .. 29/9
300 -0-300v 130mA, 6.3v. 4a. C.T. 6.3v.
la, for Milliard Amplifier . 36/9
350- 0-350v 100mA, 6.3v. 4a, 0- 5-6.3v. 3a 29/9
350 -0-350v 150mA. 6.3v. 4a. 0-5-6.3v. 3a 38/9
425-0-425v 200mA, 6.3v. 4a, C.T. 5v. 3a 57/9
425- 0-425v 200m A. (6.3v. 40 Twice), 5v. 3a 59/9
450- O-450v 250mA, 6.3v. 4a, C.T. 5v. 3a 69/9
FILAMENT TRANSFORMERS
200 -250v. 50 c/s primaries 6.3v. 1.5a, 5/9: 8.3v.
2a. 7/8. 12v. la, 7/11: 6.3v. 3a. 8 /11; 6.3v. 6a,
17/8; 12v. 1.5a, twice, 17/8.
TWEETERS H.A J ohm 25/9 15 ohm 25/9
FANE HEAVY DUTY HI FI SPEAKERS
12.20 watt. Type 122/10 Only 5 Gus.
A.S.C. POWER PACK, 39/9. Louvred
metal case only 8 x 51 x 2}ín. Stove
enamelled. For 200 -250 v. A.C. mains.
Output at 4 pin plug and socket 250 v.
60 mA, fully smoothed at 6.3 v. 2a. Suit-
able for power requirements of almost
any Pre -amp. or Radio Tuner.
ARMSTRONG, TRUVOX, LEAK,
QUAD, ROGERS, LINEAR, W.B.,
FANE, WHARFEDALE, GOODMANS
GARRARD, GOLDRI NG, GRAMPIAN,
LUSTRAPHONE, SHORE, RESLO,
TANDBERG, FERROGRAPH Products
stocked. Usual credit terms available.
RMERS (FULLY GUARANTEED)
MIDGET MAINS TRANS 21 x 21 x 211n.
250v. 60mA. 63v. 2a, 13/9
250 -0-250v. 60mA. 6.3v. Sa, 14/9
OUTPUT TRANSFORMERS
Standard Pentode 5,0000 to 3f) .. 5/9
Standard Pentode 7,0000 to 30 5/9
Push -Pull 8 watts, EL84, or 6V6 to 30
or matched tc 150 .. .. 9/9
Push -Pull 10-12 watts to match 6V6 or
EL84 to 3-5 -8 to 150 .. .. 19/9
Following types fora and 150 speakers
Push -Pull 10-12 watts. 6V6 or EL84 .. 18/9
Push -Pull 15 -18 watts, 6L6. KT66 .. 22/9
Push -Pull Mollard 510 Ultra Linear .. 29/9
Push -Pull 20 watts, sectionally wound
IL. KT66, EL39 etc. .. .. 49/9
SMOOTHING CHOKES
60mA. 10H 4000 4/11. 100mA, 10H. 2000 8/9
80mA. 10H 3500 5/9. 150mA, 10H. 2500 11/9
CHARGER TRANSFORMERS
All with 200. 230 -250v. 50 c/s Primaries:
J-9 -15v. lia, 12/9; 0- 9-15v. 2a. 14/9: 0- 9 -15v.
3a, 16/9; 0- 9-15v. 5a, 18/9; 0- 9 -15v. 6a. 23/9:
0- 9-15v. 8a. 28/9.
AUTO (Step up /Step down) TRANS.
0-110 /120- 230/250v. 50-80 watts. 13/9; 150
watts, 27/9; 250 watts. 49/9: 500 watts, 99/9
MIKE TRANSFORMERS 120:1 8/9.
SPECIAL PURCHASE OF TRUVOX D84
4 -TRACK TAPE DECKS o Carr.
3 speeds 76; 31:11 i.p.s. 7/6
Brand New and Boxed Only Gns.
(Normal price over £30)
R.S.C. GRAM AMPLIFIER KIT, 3 watts
output. Negative feedback. Controls Vol..
Tone and Switch. Mains operation 200 -250v.
A.C. Fully isolated chassis. Circuit, etc..
supplied. Only 39/9. Carr. 3/9.
SCOOP PURCHASE OF HIGH QUALITY
RECORD CHANGERS
11
Brand new Garrard 3000 LM.
Very latest model. Normal
Retail price approx. 112.16.0
Heavy Turntable and light- Carr. 5/8
weight pick -up arm. High fidelity Stereo/
Mono cartridge. Fully guaranteed.
GNS.
R.S.C. 4/5 WATT AS HIGH -GAIN AMPLIFIER
A highly -sensitive 4 -valve quality amplifier for the home
small club, etc Only 50 millivolts input is required for
full output so that it is suitable for use with the latest
High -fidelity Pick -up heads in addition to all other types
of pick -ups and practically all "mikes ". Separate Bass
and Treble Controls are provided. These give full long -
Playing record equalisation. Hum level ta negligible being
71 dB down 15 dB of Negative Feedback la used. H.T. of
300v. 25mA and L.T. of e.3v. 1.5a, is available for the supply
of a Radio Feeder Unit or Tape -Deck pre -amplifier. For
A.C. mains 200- 230 -250v. 50 e /s. Output for 2-3 ohms speaker
Chassis Is not alive. Kit is complete In every detail with fully punched Gold Hammer
finished chassis, point -to-point wiring diagrams and Instructions. Exceptional
value £4 -15 -n or assembled ready for use 25/- extra, plus 3/6 earn, deposit 22/6
and 5 monthly payments of 22/6 (Total 16.15.0) for assembled unit
R. S.C. Sl/PER IS/iI/F/4+4MPUf/ER R.SC.SCIAER30STEREO44fPI/f/ER
FULLY TRANSISTORISED 200 -250v A.C. i Kl? PRIi T -ULY INTRODUCE TWO
OUTPUT Operation. COMPLETELY NEW UNITS WITH
OUTPUT 15 WATTS R.M.S. into 14 ohms. TEl lINIt AL SPECIFICATIONS
OUTPUT 15 WATTS R.M.S. into 3-4 ohms. COPPA RING MORE THAN FAV-
Maximum Instantaneous Peak Power Out- I OURABLY WITH SIMILAR AMPLI-
yPR 28 watts. FIERS OFFERED AT 2 -3 TIMES THE
PRINTED MULLARD CONSTRUCTION. COST.
LATEST MOLLARD TRANSISTORS
ÁD349, ÁD349, 0C127Z, OC81Z, OC44, - '
OC44, OC81Z, OC44, AC107.
5 POSITION INPUT SELECTOR
SWITCH EQUALISATION to
Standard R.I.A.A. and C.C.I.R. Char-
acteristics for Gram and Tape Heads.
FULL TAPE MONITORING FAG
ILITIES SENSITIVITIES; Magnetic
P.U. 4m.v. Crystal or Ceramic P.U.
400m.v. Microphone 4.5m.v., Tape Head
2.5m.v. Radio /Aux or Ceramic Y.U.
FREQUENCY RESPONSE: 20-20 000
c.o.s.
TREBLE CONTROL +15d.b.to- 14.d.b.
at 10 Kc /s.
BASS CONTROL +12d b to -15d b at
50c /s. . . .
HARMONIC DISTORTION at 10 Watts R.M.S.1.000 c. n.s. 0.29°ó
HUM LEVEL: -75d.b. NEGATIVE FEEDBACK 52d.b.
Complete
details nd point to point wiring wiring diagrams 94 Gns . °ó /
If preferred printed circuit can be supplied with parts soldered
in and tested for 21/- extra.
Or unitffactory built. and tested, with our usuali 2 Gsae Ca r.
Or Deposit 38/- and nine monthly payments 26/7 Total 113.17.3.
Send S.A.E. for leaflet.
A DUAL CHANNEL VERSION OF Tilt:
SUPER 15. Employing Twin Printed Cir-
cults. Close Tolerance GangdPote. Matched
Components.
CROSS -TALK -82d.b. at 1,000 o.p.e,
CONTROLS:5 Position Input Selector. Bass
Control, Treble Control. Volume Control,
Balance Control, Stereo /Mono Switch, Tape
Monitor Switch, Mains Switch.
INPUT SOCKETS (Matched Pairs)
(1) Magnetic P.U. (2) Ceramic or
Crystal P.U. (3) Radio /Aux. (4) Tape
Head/Microphone.
IMPORTANT NOTE. Rated output
figures are given in R.M.S. and not speech
and music or 1.H.F.M., otherwise we could
obviously quote much higher outputs.
Operation of the Input Selector Switch
assures appropriate equalisation.
Rigid 18 s.w.g. Chassis. Size approx. l2'
Wide, 3' High, and 8' Deep.
Attractive Facia Plate and Matching
Knobs. Neon Panel Indicator.
Above facilities, etc., except for Gang-
ing and Balance Control, apply also to
Super 15.
THESE UNITS ARE EMINENTLY
SUITABLE FOR USE WITH ANY
MAKE OF PICK -UP OR MICRO-
PHONE (Crystal, Ceramic, Magnetic, Moving Coll. Ribbon)
CURRENTLY AVAILABLE. REGARDLESS OF THE
COST. SUPERB SOUND OUTPUT QUALITY CAN BE
OBTAINED BY USING WITH FIRST RATE ANCII.LARY
EQUIPMENT, Carr. 12/6
All required parts, point to
m point wiring dia-' 8
gras and detailed Instructions. If required GNSi.
printed circuits can be supplied with appropriate components
assembled, soldered and tested for 2 gas. extra.
Terms : Deposit6gns,&9 monthlypayments 88/ 8.Tota1 $22.14.8.
Or unit completely assembled ready for use Carr. 15/- 23 gus.
Or Deposit 14.14.6 & 9 monthly payments 48/8 Total 828.11.0.
www.americanradiohistory.com
644 PRACTICAL WIRELESS December, 1965
R.S.C. STEREO 20 /HIGH FIDELITY AMPLIFIER
PROVIDING 10/14 WATTS ULTRA LINEAR PUSH -PULL OUTPUT ON EACH CHANNEL
SCI'l'ABLE w, " 1111: I:" GRAM., RADIO OR TAPE. INTENDED FOR THE
HOME OR STUDIO BUT SUITABLE FOR LARGE HAILS OR CIL It»
FREQUENC RESPONSE±2dB. 30. 20,000 e.p.%
HUM LEVEL 05dB down.
SENSITIVITY: 5 millivolts maximum.
HARMONIC DISTORTION (each channel) 0.2%.
* Four- position tone compensation and
Input Selector switch.
* Will amplify direct from Tape Heads.
* Stereo'Mono switch to that peak monaural
output of 28 watts can be obtained.
* Separate Baas "Litt" and "Cut" and treble
"Litt" and "Cut" controls.
* Neon panel indicator.
* Handsome Perspex Fronlplate.
Send S.A.E. tor illustrated leaflet.
Based on a current Mullard design and employing valves
ECC83, ECC83, F,CU(I), ECEOS. F:Cl.Otl, ECL.00, E7.81.
Output transformers are high -quality sectionally wound
to required specification. Output matching.. for 3 au,l
16 ohm speakers on each elallifir I Ih.
Complete set of parte with point-to. 1 3 Gns.
point wiring diagrams and incirnc-
tions, or Factory assemble,, tested and .npplle.l alit
our w.nal 12 mouths guarantee for 18 gin. or DEI'OSl'1
57/- and 9 monthly payments of 89/10 (total 820.15.6.
AUDIOTRINE HI -FI TAPE RECORDER KIT 252 Gns:
171 6.
REALISM AT INCREDIBLY LOW COST, CAN BE ASSEMBLED IN AN HOUR
Incorporating the latest Collar() Studio Tape Transcriptor. The Audfotrine High Quadty Tape Amplifla r
with negative feedback equalisation for each of 3 speeds. High Flux P.M. Speaker, empty Tape Spool, a
Roelof Best Quality Tape and a Handsome Portable Carrying Cabinet tastefully covered in two contrasting
shades of Rexine and Vynair. Size 148 x 15 x Ellin. high and circuit. Total cost it purchased Indiv dually
approximately 240. Performance equal to units in the 460 -480 class. S.A.E. for leaflets. 'PERMS. Deposit
4 glee. and 12 monthly payments of 42/- ('l'otaI 28 (100.) ONLY 3
R.S.C. A10 30 WATT ULTRA LINEAR HIGH FIDELITY AMPLIFIER o üi é ö
JoINTs
A highly sensitive Push -Pull high output unit with sett -contained
Pre-amp. Tone Control Stages. Certified performance figures
compare equally with most ex-pensive amplifiers available. Hum
reel 70 dB down. Frequency response is 8(1ß 30-20,000 ele. A
specially designed sectionally wound ultra linear output transformer
Is used with 807 output valves. Alt components are chosen for
reliability. Six valves are used EF86, EF86, E12183, 807 807 O'J,34.
Separate Bass and Treble Controls are provided. Minimum
input required for full output is only 12 millivolts so that
ANY KIND OF MICROPHONE OR PICK -UP IS SUITABLE.
The Ink is designed for CLUBS, SCHOOLS. THEATRES.
DANCE HALLS or OUTDOOR FUNCTIONS, etc. Fog ate
with Electronic ORGAN. BASS, LEAD OR RHYTHM
GUITAR STRING BASS, etc. For standard or long -playing
records. OUTPUT SOCKET PROVIDES L.T. and H.T. for
RADIO FEEDER UNIT. An extra Input with associated vol. control is provided so that two separate Inputs
each as Gram and "Mike" can be mixed, 200 -250v. 50 cis. A.C. Maine output for 3 and 15 ohm speakers
Complete kit of parts with fully punched chassis and point -to -point wiring diagrams and Carr. IO)-
Watructioa Supplied factory built with EL34 output valves and 12 mouths' guarantee, 11 Gns.
for 14 One. If required perforated cover with carrying handles can be supplied for 19/9.
Bend 0.A.11. for leaflet, also speaker. Terms: DEPOSIT and 45/- 9 monthly payments of 32/4 ,Total 16 gns.)
INTEREST CHARGES REFUNDED Accounts aetLedlno months
LINEAR 'TAPE PILE -AMPLIFIER. 'l'ype LP/I. Switched Equalisation. Positions
for Recording at liln 311n., 7á1n, per sec.. and Playback. F)2184 Recording Level
Indicator. Designed primarily as the link between a Collar() ('ape Deck 91 Gns.
and HI -FI amplifier, suitable almost any 'l ape Deck. S.A.E. for leaflet. 2
HIGH FIDELITY 12 -14 WATT AMPLIFIER TYPE All
PUSH -PULL ULTRA LINEAR
OUTPUT "BUILT -IN" TONE
CONTROL PRE -AMP STAGES
TWo input sockets with associated controls allow
mixing of "mike" and gram., as in A10. High
sensitivity. Includes 5 valves. ECC83, ECC83,
EL84, EL84, EZ81. High Quality sectionally wound
output transformer specially designed for Ultra .
Linear operation and reliable small condensers of ?.
current manufacture. INDIVIDUAL CONTROLS
FOR BASS AND TREBLE Lift" and "Cut ".
Frequency response ±3 dB 30- 20,000 Os. Six nega-
tive feedback Loops. Hum level 60 dB down. ONLY
23 m1111volts input required for FULL OUTPUT.
Suitable for use with all makes and types of pick -ups and microphones. Comparable with
the very best designs for STANDARD or LONG PLAYING RECORDS. For MUSICAL
INSTRUMENTS such as STRING BASS, LEAD or RHYTHM GUITARS, etc.
OUTPUT SOCKET with plug provides 300v. 30rnA, and 9.3v. 1.5a, for supply of a RADIO
FEEDER ('NIT. Size approx. 12 x 9 x lin. Fol A.C. mains 200 -250v. 50 c.p.s. Output for 3
and 15 ohms speaker. Kit is complete to last nut. Chassis is fully punched. Full instruc-
tions and point -to -point wiring diagrams supplied. Only 8 Gns. r.
(Or factory built 51/6 extra,. l0l-
Car
If required louvred metal covers With 2 carrying handles can be supplied for 18/9. TERNS
ON ASSEMBLED UNITS. DEPOSIT 33/3 and 9 monthly payments of 24/1 (Total
£12.10.0). Send S.A.E. for Illustrated leaflet detailing Cabinets, Speakers, Mikes, etc.
R.S.C. STEREO /TEN HIGH QUALITY AMPLIFIER
A complete set of parts for the construction of a stereo-
phonic amplifier giving 5 watts high quality output on
each channel (total 10 watts). Sensitivity is 50 milli-
volts. Suitable for all cristal stereo heads. Ganged
Bass and Treble Control give equal variation for "lift"
and "cut". Provision is made for use as straight
(monaural) 10 watt amplifier. Valve line -up ECC83,
ECC83, EL84, EL84, EZ81. Outputs for 2-3 ohm speakers.
Point -to-Point wiring diagrams and in-
structions supplied. Send S.A.E. for leaflet. 8 Gns.
Full constructional details and price list 216.
Or supplied factory assembled with 12 months' guarantee for E11.7.6. Carr. 10/ ,
Terms: Deposit 2 gus. and 9 monthly payments of 24/2 (Total £12.19.6).
GL3A MINIATURE 2-3 WATT GRAM Always in Stock at keen prices SINGLE
AMPLIFIER. For use with any sin;le and AUTO RECORD PLAYING
or auto-change unit. Output for 2/3 ohm UNITS, PICK -UPS, CARTRIDGES,
speaker. For 200 -250v. A.C. mains. Glee MICROPHONES, CABINETS
111 x 24 x 211n, Volume and Only 59/6 VALVES and COMPONENTS
ToneControlawith Switch, TOO NUMEROUS TO LIST
l'I.lS
11AIN5
12in. IO WATT HIGH QUALITY
LOUDSPEAKER
In walnut veneered
cabinet. Gauss 12.000
lines. Speech coil 3
ohms or 15 ohms.
Only ÿA.19.6
Carr. 5/6
Terms: Deposit 11/3
and 9 monthly payments '1(05
of 11/3 (Total 25.12.8).
121n. 20 WATT HI-Fl LOUDSPEAKERS
IN CABINETS. Size 18 x £7.19.6
18 x 10in. Finish as above.
Terms: Deposit 17/8 and 9 monthly Pay-
ments of 17/9 ('fetal 28.17.6). Carr. 8/8.
W.B. "STENTORIAN" HIGH FIDELITY P.M.
SPEAKERS HP1012. to watts rating. Where
really good quality speaker at a low once is re-
quired we highly recommend this unit ith at
amazing performance. Please state £4. 19.6
whether 3 or 16 ohm required.
R.B.C. JUNIOR BASS REFLEX CABINET. Design-
ed for above speaker. but suitable for any good
quality Ola. or 101n. speaker. Acoustically lined and
ported. Polished Walnut veneer finish. Size 1 O x 12
10ín. Strongly made. Handsome Carr. £4.7.6
appearance. superb reproduction 5/-
R.S.C. STANDARD BASS REFLEX CABINET. For
12in. loudspeaker acoustically hued And ported
Size 20 x N x 13in. Beautiful walnut veneer fin-
ish. Reconnnetelet for
u .se xd Aud,nerme
9Peaket £5.19.6
öy isms
AUDIOTRINE CORNER
CONSOLE CABINETS
Strongly made. Beautiful
polished walnut veneered
finish. Pleasing design.
JUNIOR MODEL. For
up to Hin. speaker.
Approx. 20 s 11 49/9
öln.
STANDARD MODEL. To
take up to loin. speaker.
size 27 x 18 a 18in.
5 Gns. Carr. 761
SENIOR MODEL. To take up to 12in. speaker and
with Tweeter cut-out. Size approx. SO x 30 x 16in.
(Reoommended for use wits Audiotrine speaker
system.) Carr. 8 /0. 8 Gns.
Terms available.
AUDIOTRINE H1 -FI SPEAKER
SYSTEMS Consisting of matched 1215.
12,000 line, 15 ohm high quality speaker:
cross -over unit
(consisting of
choke, conden-
ser, etc.) and
Tweeter
Smooth res-
ponse and ex-
tended fre-
quency range
ensure surpris-
ingly realistic
reproduction.
Standard 10
watt rating.
£4.19.9 C5 rr
Or Senior 20 watt. 26.19.6. Carr. 7/6.
www.americanradiohistory.com
R. S. C.
December, 1955 PRACTICAL WIRELESS 645
R.S.C. BASS -REGENT 50 WATT AMPLIFIER
AN EXCEPTIONALLY POWERFUL HIGH QUALITY ALL -PURPOSE UNIT
For lead, rhythm, bass guitar and all other musical instruments
For vocalists, gram, radio, tape and general public address
* UNUSUALLY POWERFUL LOUDSPEAKER
COMBINATION consisting of a FANE HIGH
FLUX 15ín. 30 watt unit PLUS a FANE 12ín. 20
watt unit with extended frequency response.
4 Jack Socket Inputs and two independent Vol-
ume Controls for simultaneous use of up to 4
pick -ups or 'mikes'.
* Separate cabinets fully covered in contrast-
ing tones of Rexine /Vynalr with gold trim-
ming for speakers and amplifiers.
* Separate Bass and Treble Controls giving
'Boost' and 'Cut'.
Send S.A.E. for leaflet. Or call at one of our
many branches and compare the Bass- Regent
dOwith units at more than three times the cost.
Gns. Or deposit £7.16.0 and 12 monthly pay -
Ca r. 25/- meats of 81 /6 Total of 54 Gns.
" t&1gtit _ _ TRANSISTORISED SOUND MIXER
Enables mixing of up to 4 standard lack inputs,
i.e. min., tape, gram, tuner, etc., into single
output. Compact and completely self- 49/9
contained, uses standard 9 volt battery
Full Range of FANE and GOO U-
MANS Speakers in Stock and all type
'Mikes'. Credit terms if required.
R.S.C. B20 MULTI- PURPOSE AMP.
especially suitable for Bass Guitar
A highly efficient unit incorporating massive
14in. high dux loudspeaker .pecially constructed
to withstand heaviest load conditions. Rating
25 watt,. Individual bass and treble
controls give ample 'Boost' and 'Cut'. :
Two tack socket Inputs separately con-
trolled. Cabinet is of substantial con-
struction and attractively finished in
two contrasting tones of Resine and
Vynair. Size approx. 24 x 21 a 13 ins.
Send S.A.E. 29 Carr.
17/4
for leaflet.
Or deposit 24.14.8 and 12 monthly
payments of 49/- (Total 321 gas.).
R.S.C. GI5 15 WATT AMPLIFIER for Lead
or Rhythm Guitar, 'Mike', Gram or Radio
High -fidelity push -pull output. Separate bass
and treble "Cut" and "Boost" controls. Twin
separately controlled inputs so that
two instruments or "mike" and pick-
ups can be used at the same time. Loud-
speaker is a heavy duty flux 12ín 20
watt model with cast chassis. Cabinet
is covered in contrasting shades of
Rexine /Vynalr. Size approx, 18 a 18
Only 19 GnS. OR DEPOSIT 3 Gns.
and 12 monthly payments of 31/6
(Total 21 ans.) Send S.A.E. for leaflet.
R.S.C. G5 AMPLIFIER 4 watt high quality output. Incorporating high flux 12ín. 10 watt.
loudspeaker. Sensitivity 40 mv. High impedance lack input.
Handsome cabinet (size 14 x 14 x71n. approx.) finished in Rexine /Tygan, 200 -250v. A.C. mains.
Suitable for Lead or Rhythm 19 Or Deposit 30/9 and 9 monthly payments
Guitar in home or small club etc. ..6 of 22/3 (Total 11 Gus.) Carr. 7/6
R.S.C. BATTERY CHARGING EQUIPMENT Guaranteed 12 months
All for A.C. Mains 200 -250 v SOcs
Assembled
4 amps 6 /12v.
Fitted, Am-
meter and
variable
charge rate
selector.
Also selector
plug for 6 v.
or 12v. charging. Louvred steel case
with stoved grey hammer finish. Fused
and ready for use with mains 59 9
and output leads and clips.
Or Deposit 12/- and 5 monthly Carr. 4/6
payments 12 /- Total 23.12.0
CHARGER AMMETERS
0-1.5a., 0 -4a., 0-7a., 8/9 each.
A 9sEMBLED BATTERY CHARGER KITS
6/12 v. S amps.
Fitted Ammeter
and selector
plug for 6 v. or
12 v. Louvred
metal case fin-
ished attractive
hammer blue.
Fused. ready for
use with mains
and output leads
Carr.
3/9.
6/12v. > amo 27/9
Less meter.
39/9
Consisting of Mains Trans-
former, F.W. Bridge. Metal
Rectifier, well ventilatedsteel
case. Fuses. Fuse -holders
Grommets, panels, Heavy
Duty Clips, circuit. Carr. 3/6
6v. or12y. 1 amp 22/9
As above with ammeter 28/9
6v. or12v.2 amps 25/9
6v, or 12v. 2 amps, inclu-
sive of ammeter 35/9
It v. or 12 v. 4 amps with
Ammeter and variable
charge rate selector 52/9
R.S.C. 4 WATT GRAM. AMPLIFIER
KIT. Complete set of parts to build a good
quality compact unit suitable for use with
any record playing unit. Mains isolated
chassis separate Bass and Treble
controls. Output for 2 -3 ohm 59 9
speaker. For 200 -250v. A.C.
R.S.C. BABY ALARM or INTER -COMM
KIT. Complete set of parts with diagrams,
etc. Housed in two polished walnut finished
cabinets of pleasing design. High sensitiv-
ity. For 200 -2.50v. A.C. mains. Fully isolated.
Controllable at both units. An intercomm.
of this class would normally cost £20 -£30.
Only 89/6, carr. 5/- ready for use, 6 gus.
R.S.C. BATTERY TO MI S CONVER-
SION -
BMI. An all -dry
battery elimina-
tor. Size 51 x
41x2In. approx.
Completely re-
places batteries
supply 1.4v and
90v where A.C.
mains 200 -250v.
50 c/s Is avail-
able. Suitable for all battery portable
receivers requiring 1.4 v. and 90v. Complete
kit with diagram 39/9 or ready for use 48/9
EX
R CTIFOIERS 2vL SNAMP 9/9
(BRIDGE) F.W. ONLY
TANNOY RE- ENTRANT LOUD-
SPEAKERS. For outdoor or
Factory use, 8 ohms. 8 watts.
Pius 4/6 carriage
HI -FI 12 WATT AMPLIFIERS
BRAND NEW arr
EX- GUITAR AMPLIFIERS 8 Gns. 6/b
Manufacturers' discontinued Model
Push -pull output. Latest high efficiency
valves Dual separately controlled Inputs
for 'Mike' and gram. Separate Bass and
Treble Controls. High Sensitivity. Out-
put for 3 or 15 ohms speaker. Guaranteed
tested and in perfect working order.
JASON FMTI V.H.F. /F.M.Radlo Tuner
design. Total cost of
Parts including valves, tuning £6.19.6
dial, escutcheon, etc.
SUI'ERHET FEEDER UNIT. Design of
a high quality Radio Tuner (specially
suitable for use with our Amplifiers)
Delayed A.V. /C. Controls are Tuning,
W /Ch. and Vol. Only 250v. 15mA H.T. and
L.T. of 6.3v. 1 amp. required from amplifier
Size approx. 9 x 6 x 7ín, high. Simple align-
ment procedure. Point -to -Point wiring
diagrams, instructions and priced parts
list with illustrations. 2/6. Total building
costs £5.5.0. S.A.E. for leaflet.
TRANSISTOR SALE Mullard 0071 2/11.
0C45 3/11, OC44 3/11, 0072 2 /11, 0081 2/11,
0C171 8/9, AF117 6/9. Ediswan XA101 3/9.
XA112 3/9. XC101A 3/9. Postage 6d. for up
to 3 transistors.
27!6
INTEREST CHARGES
REFUNDED ON H.P.
ACCOUNTS SETTLED IN
6 MONTHS Aodresses Page 643
R.S.C. COLUMN SPEAKERS
Covered in two -tone Rexine/
Vynair. Ideal for vocalists and
Public Address. Normally sup-
plied for 15 ohm matching but
can be supplied for 100v. line
for 35/- extra.
Type C58, 15 -20 watts. Fitted
five 8ín. high flux speakers.
Overall size approx. 42 a 10 x 51n.
122 Gns- Darr. Or depoasnld
9 monthly payments of 27/9
(Total 514.9.9).
Type C412. 40 watts. Fitted
four 12ín. 12,000 line 10 watt
speakers. Overall size 56 x 14 x
91n. approx. 19, Gns.
Carr. 15/ -.
Or deposit of 3 gas, and 9 mthly
pymts of 43/2 (Total 211 gas).
30 WATT HI -FI AMPLIFIER
FOR LEAD, RHYTHM BASS GUITAR
and for VOCAL or INSTRUMENTAL
GROUPS.
A Four input,
two volume con-
trol HI -Ft unit
with separate
Bass and Treble
'Cut' and 'Boost'
controls. De-
signed for vocal
or Instrumental
groups. For Bass
Lead or Rhythm
Guitar. Mullard
or Brimar latest type valves. Housed In
strong Rexine covered cabinet with twin
carrying handles. Attractive black and gold
perspex fascia plate. For 200 -250v. A.C.
mains, Output for 3 or 15 ohm speakers.
Carr, Send S.A.E. for leaflet.
17 or Deposit 5s and 9. monthly
payments of 37 / -. (Total
£19.13).
HEAVY DUTY CHARGER KIT
hilt v. 6 amps., variable output
Consisting of Main Transformer 0-200-
230 -250 v.; F.W. (Bridge) Selenium Recti-
fier: Ammeter Variable Charge Rate
Selector Panels, Plugs, Fuses. 59/9
Fuseholder and circuit. Carr. 5/6
SELENIUM RECTIFIERS F.W. (BRIDGED)
6/12v. la. 3/11 6/12v. 3a. 9/9 8/12V. 6a. 15/3
6/12v. 2a. 6/11 6/12v. 4a. 12/3 6/12v. Ma. 26/9
6/12v. 15a. 35/9
COMPLETE POWER PACK KIT
Consisting of Mains Trans.. Metal Recti-
fier Double electrolytic smoothinc choke,
chassis and circuit. For ,
200 /250 V. A.C. mains. Output I9 l'
250 v., 60 mA, 6.3 v., 2a.
COMMUNICATION RECEIVERS
RX 60 DE LUXE
4 BAN
220/240v D 50/66 g
mains opera
Lion. Fre- ;
quencies cov-
ered 1 600 Kc /s
to 30 Mc /e
continuous. incorporates 5ín. speaker. Slide
rule tuning dial 'S' meter. Internal ferrite
aerial for medium wave. Telescopic whip
aerial 58M. 10 section for short waves. Fitted
sockets for optional outdoor aerial. Head-
phones. external speaker socket. Other fea-
tures are electrical bandspread tuning. Noise
limiter, A.V.C., B.F.O,. stand by switch.
Size approx. 121 x 51 a 81ín. Handsome
crackle finished metal cabinet. Brand new
with full instructions manual. 19 Gns.
Usual guarantee. Carr. 10 / -.
I2in 25 WATT HEAVY DUTY
LOUDSPEAKERS Famous £6.19.9
make. N ',rmal price approx. 212.
Limited number. Fully guaranteed. Carr. 10 /-
LINEAR TREMOLO PRE -AMP UNIT
Suitable for use with any of our Amplifiers.
Controls are Speed (frequency
of interruptions). Depth (for 4 Gf15.
heavy or light effect). Volume
and Swf!ch.
SPEAKERS U8 watt CONE each 39/9
www.americanradiohistory.com
646 PRACTICAL. WIRELESS December, 1965
WEYRAD
TRANSISTOR COILS
The P50 series remain the most popular and widely used components for Medium and Long -wave
Transistors Superhets:-
P50 IAC Oscillator Coil for 176 pF tuning ...
P50 1CC Ist & 2nd I.F. Transformers
P50 3CC 3rd I.F. Transformers
All mounted in individual cans ;;sin. diam. x ;in. high.
RA2W Ferrite Rod Aerial 208 pF Tuning ... ... ... 1216 ea.
LFDT4 Driver Transformers ... ... ... ... ... 916 ea.
OPTIA Output Transformers ... 1016 ea.
PCAI Printed Circuit Panel ... ... ... 916 ea.
Constructor's Booklet ... ... .., 21- ea.
514 ea.
517 ea.
61- ea.
Van RECEIVER COILS
Our individual 'H' type iron -cored coils are without equal for the construction of a wide range of
receivers. For the simplest T.R.F. sets covering one or more wave -bands the Aerial and H.F. Transformer
coils are ideal. The standard superhet circuit using the ever -popular triode -hexode frequency change
layout would employ the Aerial and Oscillator coils and the coverage can be selected 'from 7 different
bands ranging from 12.5 to 2,000 metres. For a really high -performance receiver an R.F. stage can be
added by using the Aerial, H.F. Transformer and Oscillator Coils and a circuit is provided illustrating
such a layout. H Coils 3'9 each.
PLEASE NOTE OUR CHANGE OF NAME
WEYRAD (ELECTRONICS) LIMITED
REGENT FACTORY, SCHOOL STREET,
WEYMOUTH, DORSET
ß U i L D OVER 40
CIRCUITS /EXPERIMENTS
and learn Electronics
the LERNAKIT way
lip ;_LUOI J-à;
()CATHODE RAY OSCILLOSCOPE
VALLi EXPERUIEYf, TRANSI.iTO.t EXPERIMENTS
BASIC AMPLIFIER
BASBASIC
OSCILLATOR
ELECTRONIC CH
BASIC RECTIFIER
PHOTO ELECTRIC CIRCUIT SIGIAL TRACER
TIME DELAY CIRCUIT W BASIC COMPUTER CIRCUIT
BASIC RADIO RECEIVER
:QUART WAVE GEI.. iATJ.T I.I4.1R3E CODE OSCILLATOR
SIMPLE TRA. SMITTS I - ¿T:. ETC.
This complete practical course will teach you all rite basic facts
of electronics by malting eenerlments and buildin 1 apparatus
You learn how to recognise and h and le ,.li types of components
-their symbols and how to read a circuit diagram. You see how
circuits are built and how they work HI' USING THE OS-
CILLOSCOPE PROVIDED Applications of all the main
electronic circuits are demonstrated -radio reception and
transmission; photo- erectrics; computer basics; timers; con-
trol circuits, etc; including servicing techniques. NO MATHS
USED OR NEEDED. NO rrtEORt' NEEDED. NO PRE -
%IOUS KNOWLEDGE OR EXPERIENCE NEEDED. Tutor
.service available. No extras needed. Send now for FILLE
DETAILS without obligation to ad Irece below
TO: LERN " %KIT, RADIO HOUSE,
40 RUSSELL STREET, READING
Please send free Brochure without obligation --
N AME
ADDRFISS
POST
NOW tNa rpreaestarleea rmployedl P.W. 12165
SPECIAL 'BARGAINS FROM
RADIO EXCHANGE
THE S1G -GEN. A versatile Sigual lujerso. some'
Thing no constructor should be without. This
ingenious device generates an audible algnei
through the Audio and RF ranges. With variable
.ntput. Telescopic Probe. Pocket size slim line
measures 41 x 3} ' . Complete sei of part.
with to n.tracrinns. 19/6. P. a P. I/h
fUNINd tONDeNSERS. Au -paged hoe onaun
m+nufactsvr ,nth ,lox 'melon dry
oiu6l5. With n.chlator seetmn BRAND NEW'
ur,ly 6/6. P. a P 1di.
1200mW TRANSISTOR AUDIO AMPLIFIER.
Designed to give high quality at low cost. Th.
Superb amplifier uses 4 translators Including a
special power type operating from a 12v. battery.
Variable input Impedance. Matches directly into
23 -33 ohms loudspeaker. Special gain control
orcnit Oan also redoee noise to minimlmt. All
ir,,rt..menulina ,ansietor,. printed shoals board
. tc. Rill P. a F'. /ui. East buii,l Wan, tree with.
I if parts. n c sin. 1 ohm speaker 12/6. P. 6 5.1 '6
DUKE CHECK TRANSISTOR TESTER. Cheek-
u of RF and And.o Transistor -. Aso checks ire
.noise level and dads. All parts ready to be assemb-
e.1 in attractive grey ease with red grille.
complete with Dial, Knob., and slip. Speaks..
Simple assembly instructions free with sat of pets.
29 /11. P. & P. 316.
CYLDON PERMEABILITY MISERS. Fly fames.
.uanuracturer. Fuh MW coverage Fitted coupllna
coil oiaillatur rail ferrite slogs and slow motion
Iuulug with our nr, et.. GIVE AWAY PRICE lei.
P. a P 116. Switched type we extra.
HEADPHONES. gonntoe" R13e High Pm. 11í5
Headphones. blade by famous Awe.:Lean Marteta,
t r. Approx. ISO ohra impedance for direct
matching into roost transistor circuits. BRAND
NEW in original sealed cartons. lb / -. P. A P.
1.6. hitching traasfortuery for higher impedance
2/6 .extra.
RADIO EXCHANGE CO.
61, HIGH STREET, BEDFORD
See facing page for other items
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 647
NOT BUILD ONE OF OUR
PORTABLE TRANSISTOR
RADIOS...
BACKED BY OUR SUPER AFTER SALES SERVICE
All components used in our
receivers may be purchased
separately if desired. Parts price
lists and easy build plans avail-
able separately at prices stated.
Overseas post 101 -.
FIRST FOR QUALITY, PERFORMANCE & PRICE!
NEW ROAMER SEVEN Mk IV
7 WAVEBAND PORTABLE OR CAR RADIO
Amazing performance and specification * Now with PHILCO MICRO -ALLOY R.F. TRANSISTORS
FULLY TUNABLE ON ALL WAVEBANDS 9 stages -7 transistors and 2 diodes
Covers Medium and Long Waves. Trawler Band and three Short Waves to approx. 15 metres.
Push -pull output for room filling volume from rich toned heavy duty "Ceiestlon" speaker. Air spaced
ganged tuning condenser. Ferrite rod aerial for M & L waves and telescopic aerial for S Waves.
Real leather look case with gilt trim and shoulder and hand straps. Size 9 x 7 x 4in. approx.
The perfect portable and the ideal car radio. (Uses PP7 batteries available anywhere).
* EXTRA BAND FOR EASIER TUNING Total colt of parts now only .I9.6 P. & P.
OF PI RATE STATIONS etc Parts Price List and easy build plans 3l -(FREE with kit) 5,'6
. amazed at volume and
performance ... has really come
up to my expectations."
S. G. Stockton -on -Tees.
8 stages-6 transistors
and 2 diodes
Our latest completely port-
able transistor radio covering
medium and long waves.
Incorporates pre- tagged cir-
cuit board, 31n. heavy duty
speaker, top grade transis-
tors, volume control, tuning
condenser, wave change slide
switch, sensitive bin. ferrite
rod aerial. Push -pull output.
Wonderful reception of B.B.C. Home and Light, 208 and
many Continental stations. Handsome leather -look pocket
size case, only 61 x 31 x 1 {in. approx. with gilt speaker
grille and supplied with hand and shoulder straps.
Parts Price List and Total cost of all L3.9 6 P. & P.
easy build plans 21- parts now only 3i6
(Free with kit)
POCKET FIVE
7 stages -5 transistors and 2 diodes
Covers Medium and Long
Waves and Trawler Band, a
feature usually found In
only the most expensive
radios. On test Ho me, Lig ht.
Luxembourg and many
Continental stations were
received loud and clear.
Designed round supersensi-
tive Ferrite Rod Aerial and
fine tone 2 /in, moving coil speaker, built into attractive
black case with red speaker grille. Size 51 x 1f a 311n. (Uses
1289 battery available anywhere).
Parts Price List and easy build plans 116. (FREE with kit)
Total cost of all
parts now only 42/6 P. & P 31 -.
NEW ROAMER SIX
NOW WIT,: PHILC.t h Gill -ALLOY n.r. TRANsSTOHS
6 WAVEBAND ! !
8 stages -6 transistors
and 2 diodes
Listen to stations half a
world away with this 6
waveband portable. Tune-
able on Medium and Long
waves. Trawler band and
two Short Waves. Sensi-
tive ferrite rod aerial and
telescopic aerial for short
waves. Top grade transis-
tors. 3-inch speaker.
handsome case with gilt
fittings. Size 7k x 5L x 1lin.
Carrying strap 1/6 extra.
* EXTRA BAND FOR EASIER TUNING OF LUX, ETC.
Parts Price List and Total cost of all t p
easy build plans 21- parts now only `3. I 9.6 P. & P.
(FREE with kit) p y 3t6
New TRANSONA
FIVE "Home. Light, A.F.N.
Luz. all at good volume ".
G.P. Durham.
7 stages -S transistors and 2
diodes
Fully tunable over Medium and Long
Waves and Trawler Band. Incorpor-
ates Ferrite' rod aerial, tuning con-
denser, volume control. new type fine
tone super dynamic 22 In. speaker etc.
Attractive case. Size 6k x 44 x l.t1a-
with red speaker grille. (Uses 1289 battery available anywhere.)
Total cost of all 42/6 P. & P. Parts Price List and easy build
parts now only 3f6. plans 21 -. (FREE with kit)
TRANSONA SIX
8 stages -6 transistors and 2
diodes
This is a top performance receiver
covering full Medium and Long
Waves and Trawler Band. High -grade
approx. 3in. speaker makes listening
a pleasure. Push -pull output Ferrite rod
aerial. Many stations listed in one even-
ing including Luxembourg loud and
clear. Attractive case in grey with red
grille. Size 6f x 4; x l(1n. (Uses PP4
battery available anywhere.) Carrying
strap 1/- extra.
Total cost of all 59/6 P. & P-
parts now only 3/6.
Parts Price List and easy build plans 116 (FREE with kit)
SUPER SEVEN
9 stages -4 transistors and 2
diodes
Covers Medium and Long Waves
and Trawler Band. The ideal radio for
home, car or can be fitted with
carrying strap for outdoor use.
Completely portable -has built -in
Ferrite rod aerial for wonderful
reception, Special circuit incorporating 2 R.F. Stages, push -pull output.
3in. speaker (will drive large speaker). Size 7* x 51 x 1í1a. (Uses 9v
battery, available anywhere.)
Total cost of all E3. 19.6 P. & P.
parts now only 316 Parts Price List and easy
build plans 21 -. (FREE
with kit)
RADIO EXCHANGE CO
61, HIGH STREET, BEDFORD
Telephone: Bedford 52367
Callers side entrance Barratts Shoe Shop open'9 -5 p.m. Sats 10 -12.30 p.m.
ALSO SEE FACING PAGE FOR OTHER ITEMS
www.americanradiohistory.com
648 PRACTICAL WIRELESS December, 1965
STERN-ELYNE
H I G H F I D E L I T Y E Q U I P M E N T
(f) Mullard "IO Plus IO"
Stereo Amplifier
A High Fidelity design providing up
to 10 watts (per channel).
KIT OF PARTS £20.0.0.
Built and toned £24.0.0 (C. e 1. 7/6).
We can aise supply the Main Ampli-
fier for operation with our Dual
Channel Pre -amplifier.
8IT OF PARTS £27.0.4.
Butt and tested £84.0.0 (C. d L 10 /0).
(2) Mullard Dual Channel
Pre -Amplifier
A four -valve design for both stene-
pho ic and Monophonie
c11810.0. te operation.
KIT
Built and !taled 215.0.0 (0. L 6 / -).
(3) The "Twin Three"
Stereo Amplifier
Based on a recent design by Mullard
Ltd. it is ideally salted for use in
Portable Renard Player..
Built and touted 22.0.0 (C. & I. 7/6).
To construct a Stereo Portable
Record Player, we offer:
Assembled Amplifier with two
r x am. Londepeakers and Portable
Case for 216.10.0 (C. A 1. 10) -).
Fully descriptive leaflets
available on any of the
above items.
Instruction Books and
Detailed Price Lists
are supplied Free with
Kits of Parts but may be
purchased separately if
required.
Items 1, 2 and 14, 3/- each;
6 and 19, 3/6 each; 7. 8. 9,
10, 21- each; 11, 2/8 each;
13, 6/ -. All Post Free.
lis .i 010 th
(5) Tudor AM /FM Tuner
Self- powered VHF /FM long and
medium waves. FM 87.5.108.6 Mc s
AM.MW 522 -1,830 Kc)e. LW 142-
270 Kets. Multiples output.
Built and tested 24 fins. (P. d P. 7)0).
(6) Mullard 3 -Valve Pre -
Amplifier Tone Control
Designed mohair for the Stern
Milliard range of Monophonic Power
Amplifiers.
KIT OF PARTS 210.0.0.
Bailt and tested £18.18.0 (0. L 6f -).
(8) Mollard "5 -10" Main
Amplifier
For une with Mallard '2- or 3 -valve
pre- ampliftere with which an un-
distorted power output of up to 10
watts is obtained.
KIT OF PARTS 210.0.0.
Built and tested 218.10.0 (C. & 1. 6 /0).
Above inoorporating Partridge Oat -
nt Transformer 21.6.0. extra.
(9) Mullard "5 -IORC"
Amplifier
The popular "5 -10" complete m
,orpvrating Passive Control Unit
providing up to 10 watts high quality
reproduction with an input of 600mV.
KIT OF PARTS 212.0.0.
Built and tested 216.0.0 (C. d 1. 7/6).
With Partridge Output Transformer
01.6.0 extra.
(16) )LIO Power Amplifier
Incorporates the latest diode /pentode
0CL86 valves in push -Pull. Partridge
ultra linear output transformer.
Partridge mains tranelormer and
smoothing choke. 10 watts power
output. surplue.
Built and tested 612.12.0 (C. & I. 7/8).
(10) Mullard "3 -3RC"
A high quality Ampltfler developed
from the very popular 3 -watt Mallard
"34" design.
KIT OF PARTS 28.8.0.
Built and tested £11.10.0 (C. d L 6 /6).
(I 1) The "Mono -Gram"
A small Amplifier of genuine high
quality performance producing up to
3 watts undistorted output.
KIT OF PARTS 24.10.0.
Built and tested 68.0.0 (C. d I. 3 0).
VERITONE 30
AMPLIFIER
A general purpose amplifier of
outstaadmc quality ideally suit-
able for Dance Band,, Clubs.
Hotels, Factories. Indoor and
outdoor Public Address requiring
a powerful robust portable Ampli-
fier which will provide high quality
. eproduction, distortion free. The
Amplifier bas two +tandard Jack
Socket inputs, high gain and low gain
with individual volume control, and with the
master volume contra) the input- may be 11110ed and
balanced as required. Housed In a really robust steel case finished in smooth
grey hammer finish with chrome handles and silver grey front panel with
contrasting letters and knobs. Built -in Preamplifier and Control Unit.
30 watt Undistorted Output. Switched Output for 3 or 15 ohms I.gudspeakers.
Fully assembled and tented carriage and
insurance 10/-. Ventilated Cover with chrome
handles as Illustrated. 66/- extra. Price 18 Gns.
(17) Double F
Pre -Amplifier
Inputs for microphone, crystal or
magnetic pick-ups, tuner (nit, and In
addition offers full factiniee for tape
recording and high fidelity replay.
This unique feature means that
should you wish to include tape in
yon N -1 system at a later date all
that is requiredls a suitable tape deck.
Built and rested 818.18.0 (C. & 1. 514.
Penes fr both units purchaasd to-
otthee:
Bailt and tasted 830.8.0 (C. I L 10 / -l.
VERITONE 30
A small versatile 3.4 watts Gram
Amplifier suitable for Crystal Pick -up
or Radio Tuner, ideally eulted for a
sm..11 domestic installation. Output
Imp. 3 ohms, volume control, treble
control, bass control and middle con-
trol. Valve line-up: 01.84. 01e86,
07.80.
Chassie else 8} x 4 r lf ln. Silver
anodised finish. Attractive iront panel
silver grey finish with contrasting
lettering and knobs. Sise 81. x 21.in.
Fully assembled and tested 6 Gus.
(C. &
(7) MULLARD 2 -VALVE
PRE -AMPLIFIER
Employing two EF80 valves and
designed to operate with the Mulard
MAIN AMPLIFIERS but also per-
fectly suitable for other make,. Nnw
with new design front panel.
KIT OF PARTS 20.0.0.
Built and tested 20.10.0 (0.d 1. 6(-).
*el
(12) Stereo Tape Pre -
Amplifier Model STP -I
For use with current Travoz, Bren-
ell or Collars "Studio" 0- and I -track
Stereo Desks. Now with new design
front panel.
KIT OF PARTS 222.0.0.
Built and tested 222.0.0 (C. & L. 8/6).
(13) Mullard Type "C" Tape
Pre -Amplifier
Buitable for moot, f -track Mono
Tape Decks. Now with new design
front panel.'
KIT OF PARTS 214.0.0.
Built and tested 219.10.0 (0. & 1. 716.
a.. t gIt .
'..; $
2:6 O 0:
(14) Mullard Tape
Amplifier Model HFITR3
Based ou Mallard's type "A" design
and suitable for moat 4-track Mono
Tape Decks. Now with new design
front pane.
KIT OF PARTS 218.18.0.
Salit and tested 218.0.0 (C. & 1. 7/8).
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 649
STERN-CLYNE Appointed stockists for the
v
New V e rit OÌÌ e range of hi -fi equipment
TWO ENTIRELY NEW DESIGNS FOR
THE MODERN -MINDED HI -FI ENTHUSIAST
THE VERITONE SATURN
TRANSISTORISED FM TUNER
SPECIFICATION: Transistors: I x AF125, 1 x AFI21, 4 x AFI 16.
Diodes: 4 x 0A79, 1 Variable Capacity Diode, Solid State Full Wave
Bridge Rectifier, I OAZ212 Zener Diode. 4 I.F. Stages. Switchable
A.F.C. Tuning Meter. Facility for plug -in Multiplex Stereo
Adaptor (available at a later date). Tuning Range: 87.5-
108.5 Mc /s. Stabilized Power Supply. Din Outlet Socket. Fully
Variable Audio Output Attenuator. Supplied with or without
Plastic Laminated Case (Teak). Sensitivity 4mV. for 30dB signal to
noise ratio. Attractive Black and Silver Grey front panel with
mirror strip top and bottom.
PRICE 25 G NS. Carriage & Insurance 716
Teak case optional extra.
THE VERITONE VEGA
TRANSISTORISED STEREO AMPLIFIER
SPECIFICATION: Power response, with channels used simul.
taneously, 13 watt R.M.S. per channel, at 50 c,s and 10 Kc /s the
above features are reduced by approximately 2 watts. Loudspeaker
impedance 15 ohm. Frequency response on unequalised input, flat.
+ 1dB from 40 c/s to 20 Kc,s. -3dB at 20 c /s. Total harmonic dis.
tortion at 10 watts approximately 0.5°x. Cross talk, -50dB at IKc
15dB. Hum and noise- 5060dBs on Radio, Aux., Tape and
Magnetic P.U. -50dBs on Ceramic P.U. _I -3dB. Controls: Bass.
Treble and Balance. Inputs for Radio, Tape, Aux, Magnetic P.U. and
Ceramic P.U. Tape Output and Tape Monitor. Mains input 200 -220.
240 volts. Transistors per channel 5 x 0C45, 2 x 0C35 or 0C29,
2 x ACY17, I x 2N696, 6 x Diodes per amp. Dimensions: I I x 4, x
6áìn. Front Panel: Silver Grey with contrasting Black markings and
knobs. Operation: 200/250 volts A.C. 50 c /s.
PRICE 39 GNS. Carriage & Insurance 101 -
Teak case optional extra.
NOW ON DEMONSTRATION AT ALL BRANCHES
ETERN-ELYNE
SEE FOLLOWING PAGE FOR ADDRESSES'
www.americanradiohistory.com
650 PRACTICAL WIRELESS December, 1965
5TERN-ELYNE
ELECTRONIC CENTRES THROUGHOUT GREAT BRITAIN
TR2 PORTABLE TAPE REOORDER. A truly first -class portable machine
by famous manufacturer incorporating the renown BS R single speed' --' -track
Tape Deck. 31 1.p.e. Tape Counter. Record Level Indicator. Volume
and On /Off Tone Control. 3 watts output. Input for recording from
Microphone and Radio. Tape Monitor Socket. Extension Loudspeaker
Socket. Attractive two -tone grey/eream rexine covered Portable Cabinet.
Supplied complete with Microphone, Reel of Tape and Spare Spool.
Carriage and Insurance 15 /- extra. Credit Originally 23 Gus.
Terms 22.18.0 deposit and 12 monthly pay- 1$ Gns.
mente of 21,9.4, total credit price 220.10.0. OUR PRICE.
114ttYAUTOMATIC TAPE SPLICER
84/6. P. d 1'. 1;6.
PLASTIC TAPE SPOOLS
31n., 1/3: 4fn., 21-i 31... 2 / -: 531n., 2/3;
710., 2 /e.
PLASTIC SPOOL CONTAINERS For
spool sizes yin., 1 /6; 551n., 2l -;
7ín., 2 /3. Any single item plue 6d.
P. d P. Orders over 21 poet free.
We carry fully comprehensive stocks
of Tape Recorders. Decks and Acces-
sories at all Branchu or order with
confidence by mail.
AMERICAN
RECORDING TAPE
600ft. Std. Acetate .. 8/8
900ío. LP Acetate .. 10 /-
52ìn. 1.200ít. LP Acetate , . 12/8
7Ì0n 1,200ft. Std. Polyester.. 12 /8
5in. 1,200ft. DP Polyester .. 15/-
710. 1,800ft. LP Pulyestet ..
5'In. 1..001t. DP Polyester .. 22 /6
710. 2,460fí. UP Polyester .. 25 /-
P. & P. 1/- per reel. 4 or more reels
POST FREE.
TRI PORTABLE TAPE RECORDER, A high quality Portable Tape Rec-
order for the discerning enthusiast incorporating the latest BOIL TU10
3 -speed Tape Deck. 11. 31 and 72 i.p.s. 2- Track. Record interlock to
prevent accidental erasure. Tape Counter. Record Level Indicator.
3-4 watt .mtpuf. Volume and On /Off Tone Control. Inputs for recording
from Microphone and Radio. Tape Monitor Socket. Extenslon Loudspeaker
Socket. Attractive two -tone blue realm covered Portable Cabinet with
silver trimmings. Supplied complete with Microphone. Lead for recording
from Radio or Record Player. Full Reel of Tape and Spare Spool. Carriage
and Insurance 16 /- extra. Credit Terms: Originally 28 Gus.
23.8.0, depost and 12 monthly paymtente
of 21.12.3. Total credit price 222.10.0 OUR PRICE 20 Gns.
ETCH YOUR OWN
PRINTED CIRCUITS
A complete kit of parts to
make your own printed circuit
board to your own specifica-
tion, high quality materials
used to ensure perfect results.
Price complete with all neceo
vary chemicals and copper
clad laminated board, 19/6.
2/3 packing and postage.
19 Tottenham Court Road, W.1 MUSeum 5929/0095. Halt Day Saturday.
23 Tottenham Court Road, W.1. MUSeac. 3451/2. Half Day Thursday.
309 Edgware Road. W.2. PADdington 6903. Half Day Thursday.
1.09 Fleet Street, E.C.4. FLEet Street 5612/3. Half Day Saturday.
162 Holloway Road, N.7. NORth 7941. Hall Day Thursday.
9 Camberwell Church Street, E.E.O. RODney 2876. Half Day Thursday.
NOW ALSO OPEN AT:
220 Edgware Road, W.E. PADdington 2607 (New -Max).
CROYDON
12 Suffolk House, George Street, MUNIcipal 3260, Halt Day Wednesday.
BRISTOL
26 Merchant Street, Brletot 1. Bristol 20281. Open 6 days a week.
* MEDIUM AND LONG WAVES. *12 VOLT
POSITIVE EARTH. *Push Button Wave Change.
*SIZE 7 x 2 x 7in.
9 2 Gns Ready ballt complete with 7 z 41n.
speaker fitted to baffle fixing brackets,
P. & P. 5/- all nuts and bolts and fitting instruc-
tions.
Optional Extras: Chromium plated weatherproof telescopic aerials. Type
1, 22In50nL, 19/8. Type 2, 1210.%4310, E9 /6. Type 3, fully retractable
and locking lm.150in. Depth below wing. 14in.. 39/6. AU plus P & P. 2/6
if purchased .separately.
ANOTHER
NEW CENTRE
Opening
Shortly at
EASTOWN
HOUSE
LINCOLN ST.
NOTTINGHAM
LIVERPOOL
52 Lord 'lbeet, I:o. 7450. Open 6 days a week.
MANCHESTER
20/22 Withy Grove, Manchester 4, BLAckfrlaes 5379/5248
Open 6 days a week
SHEFFIELD
1.25 The Moo, She/heir, Sheffield 29993. Half Day Thursday
MAIL ORDERS AND ENQUIRiES TO:
Dept. P.W. :i .i Eden Grove. Hulloxay, London. \.i.
\ORCh 0161 ;5.
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 651
SURBITON PARK RADIO
MARTIN AUDIOKITS & RECORDAKITS
F.M. TUNER i. N11 S Nos. 15. 16 and 17 Cash 212.17.8
Or Dep. 51/6 and 12m. pyrnts. of 18/10 (H.P. Price £13.17.6)
TRANSISTORISED AMPLIFIER with -5 position input selector.
pre -amp and controls. 10 watt amplifier and Power Pack.
For 3 Ohm Speaker. Cash 214.5.0
Or Dep. 57/- and 12 m. Dimas. 20/10 (H.P. Price £15/7/0)
For 15 Ohm Speaker, Cash 215.0.0
Or Dep. 62/- and 12 m. pymts. 22/6 . (H.P. Price £16.12.0)
All above Include Front Panels, Knobs and Instructions.
TWO TRACK RECORDAKIT AMP. (Valve) FOR STUDIO
DECK, 6 valves, controls, self powered Cash 211.11.0
Or Dep. 47/- and 8 m. pymts. 25/6 (H.P. Price £12.11.0)
COLLARD STUDIO DECK 3 speed latest Two Track Cash 210.19.8
Or D 441- and 8 m. pymts. 24/6 (H.P. Price £12.0.0)
COMPLETE KIT with case, saki... tape and mIo Cash 229.19.8
Or Dep. 1201 - and 12 m. pymts. 44/- (H.P. Price £32 8.0)
FOUR TRACK AMP. as above Cash 212.12.0
Or Dep. 52/- and 8 m. pymts. 27/6 (H.P.Price £13.12.0)
FOUR TRACK COLLABO DECK Marriott "X" Series heads
Cash 213.19.8
Or Dep. 56/- and 12 m. pyrnts. 2016 (H.P. Price £15.2.0)
COMPLETE KIT with case, spkr., tape and mie.
Four Track Cash 233.19.8
Or Dep. 136 /- and 12 m. pymts. 49/10 (H.P. Price 136.14.0)
TAPE PRE -AMP for Studio Deck, self powered
Two Track Cash $8/8/0
Or Dep. 34/- and 6 m. pymts. 25/8 (H.P. Price 19/9/0)
TAPE PRE -AMP as above Four Track Cash £9.9.0
Or Dep. 39/- and 6 m. pyrnts. of 28/4 (H.P. Price £10.9.0)
We are leading stockists for all Martin Constructional Kits
AMPLIFIERS TUNERS Selection
ARMSTRONG 22210 -10 watts Stereo. Amplifier Cash 227.10.0
Or Dep. 110 /- and 12 m. pymts. 40/4 (H.P. Price £29.14.0)
ARMSTRONG 224 F.N. TUNER Powered as 222.10.0
Or Dep. 90/- and 12 m. pymts. 33/- (H.P. Price £24.6.0)
ARMSTRONG 223 AM /FM TUNER Powered Cash £28.15.0
Or Dep. 115/- and 12 m. pymts. 42/2 (H.P. Price £31.1.0
ARMSTRONG 127 MONO 5W with AM /FM Cash 228.10.0
Or Dep. 106/- and 12 m. pymts. 38/10 (H.P. Price 128.12.0)
SURBITON PARK RADIO LTD.
ARMSTRONG CV STEREO as above Stereo amp... Cash 237.10.0
Or Dep. 150 /- and 12 m. pyrnts. 55/- (H.?. Price £40.10.0)
ARMSTRONG 227 MONO 10W amp. with AM /FM.. Cash £38.15.0
Or Dep. 147/- and 12 m. pyrnts. 53/10 (H.P. Price £39.13.0)
ARMSTRONG 227 STEREO as above with Stereo Amp.
Cash 252.15.0
Or Dep. 211/- and 12 m. pymts. 77/4 (H.P. Price £56.19.0)
ARMSTRONG 220 STEREO as above, but Mag. P.U. Filter
Cash 281.0.0
Or Dep. 2601- and 12 m. pymts. of 881- (H.P. Price £65.16.0)
leak Cases for all Armstrong Units 23.10.0
ROGERS CADET Mk. 3 10 -10 watt Stereo Amp. Mag. P U.
Cash 229.10.0
Or Dep. 118/- and 12 m. pymts. of 43/3 (H.P. Price £31.17.0)
CASE MODEL ROGERS CADET Mk. 3 23.0.0 extra
LEAK STEREO 30 TRANSISTOR AMPLIFIER Cash 249.10.0
Or Dep. 198/- and 12,n. pyrnts. of 72/7 (H.P. Price 153.9.1)
LOUDSPEAKERS Selection
FANE 012 /10 heavy Duty 121n. 20 watt Cash £5.5.0
WHARFEDALE SUPER 8 /RS /DD Cash £8.14.3
WHARFEDALE SUPER 10 /RS /DD Cash £10.18.0
Or Dep. 44/- and 8 m. pyrnts. of 24/3 (H.P. Price 111.18.0)
GOODMANS MAXIM Cash £17.10.8
Or Dep. 70/6 and 12 m. pyrnts. 25/8 H.P. Price 118.1.8.6)
MOTORS PICK- UPS Selection
GARRARD SRP10 Mono Cash £5.10.0
GARRARD Model 1000 Mono Cash £7.10.0
GARRARD Model 2000 Mono Large Table Cash £8.10.0
Or Dep. 34/- and 6 m. pyrnts. 26/- (H.P. Price 15.10.0)
GARRARD Model 3000 Stereo Lightweight arm.... Cash £11.11.0
Or Dep. 47/- and 8 m. pymts. 25/6 (H.P. Price £12.11.0) .
GARRARD S.P,25 Less cart.: Single player
Or Dep. 50/- and 8 m. pymts. of 27/6
GARRARD at 60 Less cart.: Heavy table
Or Dep. 52/- and 12 m. pymts. 19/-
GARRARD A 70 De Luxe changer, Less cart
Cash 212.10.0
(H.P. Price 213.10.0)
Cash 213.0.0
(H.P. Price £14.0.0)
Cash 222.10.0
Or Dep. 90/- and 12 m. pymts. 33/- - (H.P. Price £24.6.0)
GARRARD LAB 80 Push button Oper., less cart Cash 227.10.0
Or Dep . 110 /- and 12 m. pymts. of 40/4 (H.P. Price £29.14.0)
GARRARD 401 Transcription Table. No arm
Or Dep. 130/- and 12 m. pymts. 47/8
GOLDRING G66 Mono Single Player (H.P. Price 135.2.0)
Cash 211.11.0
Or Dep. 47/- and 8 m. pymts. 25/6 (H.P. Price £12.11.0)
GOLDRING GL58 less cart.: Heavy table, single play Cash 217.1.0
Or Dep. 69/- and 12 m. pymts. 24/11 (H.P. Price £18.8.0)
GOLDR ING GL70 trans.: Unit with arm, less cart... Cash 229.18.8
Or Dep. 120/6 and 12 m. pymts. 43/9 (H.P. Price 135.5.6)
Leaflets available upon receipt of 0d. stamp.
48-SO, Surbiton Road, Kingston -on- Thames, Surrey
Phone KIN. 5549:: Hours 9 a.m. to 6 p.m. daily (I p.m. Wade.)
The New Picture- Book'wayof learning
S IC ELECTRICITY(5voL.$)
ELECTRONICS (6voLs)
You'll find it easy to learn with this out-
standingly successful new pictorial method -
the essential facts are explained in the
simplest language, one at a time; and each
is illustrated by an accurate cartoon -type
drawing.
The series will be
of exceptional
ff value in training
f'f mechanics and in
technicians in electri-
ci y, Radio and Electronics.
WHAT THIS MONTH'S IN
ENTHUSIASTIC READERS SAT
EVERY DAY WE RECEIVE LETTERS PRAISING THESE 1111
BOOKS, HERE ARE A FEW FROM THIS MONTH'S POSTBAG. .
"Thank you -a casual glance through the books was enough/
A truly excellent publication, not in the least complicated in
by endless mathematics found in the normal manuals who
seem only to cater for the technical man." B.F., Weybridge.
"Man DIG THOSE MANUALS, I am at last wills III
it." K.L., Oxford.
The books are based on the latest research
into simplified learning techniques. This
has proved that the Pictorial Approach
to learning is the quickest and soundest
way of gaining mastery over these
subjects.
I1111 MIN M1111.1111111MNI1.1MN
To Selray Book Co.
60 Hayes Hill, Hayes, Bromley, Kent
Please send me Without Obligation to Purchase, Basic Electricity/
Basic Electronics on 7 Days Free Trial. I will either return set,
carriage paid, in good condition within 8 days or send down payment
of 15/. (Basic Electricity) followed by 6 fortnightly payments of
10 / -. Down payment of 15/- (Basic Electronics) followed by
6 fortnightly payments of 12/6. Alternatively, I will send 68/-
(Basic Electricity -5 parts), 81/- (Basic Electronics -6 parts) post
free. This offer applies to United Kingdom only.
Tick against set required (only one set allowed on free trial).
BASIC ELECTRICITY BASIC ELECTRONICS
Signature (If under 21, signature of parent or guardian) 4
NAME............ «..«..
BLOCK LETTERS BELOW
FULL POSTAL
ADDRESS
www.americanradiohistory.com
652 PRACTICAL WIRELESS December, 1965
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII! IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIf! IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII11111111111111111
Heathkit models offer
outstanding performance plus
highest quality - at lowest cost
Anyone can build a Heathkit model. The easy -to- follow instruction manuals issued with
each kit -set show you how. You will be proud of the professional appearance and performance
of your finished model.
A KIT FOR EVERY INTEREST . FOR HOME, WORKSHOP, SERVICE & TEST DEPTS.
O.ST.OM
TEST INSTRUMENTS
Sin. OSCILLOSCOPE Model 10.12U.
Laboratory quality at utility oscilloscope
price. Wide band amplifiers essential for
T.V. servicing. F.M. alignment. etc. T B
covers 10 c s -500 kc s in 5 ranges.
445.15.0 Assembled £35.17.6 Kit
PORTABLE 'SCOPE Model 05 -1. A
compact portable oscilloscope, ideal for
servicing and general work. Printed
circuit board. Case P. e 4, x 12 ?. in. long.
L30.8.0 Assembled £22.18.0 Kit
10 -12U
REGULATED POWER SUPPLY Model IP -20U. Transistor-
ised, 0-5-50 v. D.C. Up to 1.5 amps. Compact: 9! x 6_ x I I in.
447.8.0 Assembled £35.8.0 Kit
VALVE VOLTMETER, Model V -7A. The world's
best selling VTVM. Measures up to 1,500 volts
(d.c. and r.m.s.) and 4,000 pk. to pk. Res. 0.1 /1
1.000 MS2. Centre zero dB scale, d.c. input resistance
IIMS3. 44in. meter. Complete with test prods, leads
and standardising battery. £ 13. 18.6 Kit
419.18.6 Assembled
DE -LUXE 6in. VALVE VOLTMETER. Model
1M -130. Similar spec. to model V -7A but with im-
proved accuracy. Larger meter. Unique gimbol mount. V -7A
426.18.0 Assembled £18 . 1 8.0 Kit
R.F. and H.V. probes available as extras.
DE - LUXE TRANSISTOR
TESTER. Model IM -30U. Many
special features. Provides complete
d.c. analysis of PNP, NPN tran-
sistors and diodes.
435.10.0 Assd.
HARMONIC DISTORTION METER.
Freq. coy.: 20- 20,000 c s.
L34.0.0 Assembled
£24.18.0 Kit
Model IM -12U.
£24.15.0 Kit
TV ALIGNMENT GENERATOR. Model HEW -I. Covers
447.10.0 Assembled £37.18.0 Kit
RF SIGNAL GENERATOR. Model RE -IU. Up to 100 Mcls
fundamental, 200 Mc /s harmonics. Up to 100 enV output on all
bands. ¿19.18,0 Assembled £ 13.8.0 Kit
MULTIMETER. Model MM-1U. Ranges: 0.1 -5 v. to 1,500 v.
a.c. and d.c.; 150µA to 15A d.c.; 0.212 to 20010. 41 in. 50µA meter.
418.11.6 Assembled £ 1 2. 18.0 Kit
A wide range of other test instruments available including: RIC
Bridge C -3U ¿10.10.0. AF V /Voltmeter AV -3U 416.10.0.
Wattmeters AW -I U, 417.5.0. Capacitance meter CM -I U
¿15.15.0. Power supplies. Decade boxes etc. Many other
instruments available under American Mail Order scheme.
111111111 1111111111111111111111 I 111111111111111111111111111111111111111111111111111111111111111 P
DAYSTROM
Dept. PWI2 GLOUCESTER, ENGLAND
3.6 to 220 Mc,ls fundamentals.
LTD
"AMATEUR" EQUIPMENT
AMATEUR BANDS RECEIVER
Model RA -I. Covers all amateur
bands Irons 160 -10 re. Half lattice
crystal filter. 8 valve. "S" meter.
tuned R.F. amplifier :tage.
£39.6.6 Kit
Assembled L52.10.0 RA -I
AMATEUR TRANSMITTER. Model DX -1000. Covers
all amateur bands 160 -10M. 150 w. d.c. input, self contained
with power supply. Modulator. VFO £79.10.0 it
Assembled L104.15.0
AMATEUR TRANSMITTER
Model DX -40U. Covers 80 -10 m.
Power inputs 75 w. C.W.. 60 w.
peak C.C. phone. Output 40 w. to
aerial. Prov. for VFO.
DX-40U
COMMUNICATIONS TYPE
RECEIVER RG -I. A high perform-
ance low cost receiver for the dis-
criminating listener. Freq. coy. 600
kc;s -1.5 Mc /s and I.7 Mcis to 32 Mc /s.
Send for details. £39.1 6.0 Kit
453.0.0 Assembled
Other kits in the amateur range include: SSS Adaptor SB -IOU
E39.5.0. Variable freq. Oscillator VF -1U 410.17.6. Balun
Coil Unit B -IU E4.15.6. Grid -Dip Meter GD -IU L10.19.6.
Q Multiplier HPM -I ¿8.10.0. Reflected Power Meter HM-
I 1U L8.5.0, Wide range of models under American Mail Order
Scheme.
£33.19.0 Kit
Assembled 445.8.0
.-11- 1.+.1-..-.14
MONEY BACK GUARANTEE
Daystrom Ltd. unconditionally guarantee that each
Heathkit product assembled in accordance with our easy -
to- understand instruction manual must meet our published
specifications for performance or the purchase price will
be cheerfully refunded.
HI -FI SPEAKER SYSTEMS
COTSWOLD STANDARD MODEL
Acoustically designed enclosure "in the white"
26 x 23 x 155in., 12ín. bass speaker, elliptical
middle speaker, tin. pressure unit. Covers
30- 20,000 c /s.
Complete kit with all controls.
MFS SYSTEM
A minimum floor space model for tiffe smaller
room. 26in. high x 165in. x 14in. deep. Similar
performance to standard model. £25.12.0 Kit
Price either model
SSU -I SYSTEM
A practical solution to the problem of a
moderately priced speaker suitable for Stereo
Mono amplifiers where the equipment has to
be compact. Two speakers, balance control,
ducted port reflex cabinet.
Horizontal or vertical (with matching legs).
Incl. P.T. £ 12.1 2.0 Kit
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 653
IIIIIIIIIII! III111111111 (1(IIIIIIII1111111!IIIII(ill IllIII111 (111111111(11111111111! 111111111111111 '111111111I(!'1(IIlI( IIII IIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII III1111!IInI il'nllllll
MODELS FOR HOME, TEST AND WORKSHOP.
BRITISH HEATHKIT MODELS USE BRITISH COMPONENTS
HI -FI AMPLIFIERS
DE -LUXE ALL TRANSISTOR STEREO AMPLIFIER, AA -22U.
At last, a British transistor amplifier with high power (20 + 20W) at
a reasonable cost, capable of delivering full power at all frequencies
in the audio band. Handsome fully finished walnut veneered cabinet
available. Professional slim -line styling. Send for full specification.
Kit (less cabinet) 439.10.0. Cabinet £2.5.0. Brackets and trim for panel mounting 41.18.0.
.,..u.I .i
DAYSINOM
.1111.
6W DE -LUXE STEREO AMPLIFIER. Model S -33H. An
inexpensive stereo amplifier with high sensitivity. Suitable for
use with Decca Deram cartridge. £15.17 .6 Kit
(21.7.6 Assembled
TAPE RECORD /REPLAY AMPLIFIER KITS. Will operate
with most tape decks. Send for details.
TA -IM (Mono), (19.18.0 Kit. TA -IS (Stereo), (25.10.0 Kit.
STEREO CONTROL UNIT. Model USC -I. Ideal for use with
MA -12 amplifiers. Kit (19.10.0. Assem6led (26.10.0.
6W STEREO AMPLIFIER
Model S -33. 3 w /ch. Inputs for
radio, tape and gram. Stereo,Mono
ganged controls. Sensitivity 200mV.
(18.18.0 Assembled£ 1 3.7.6 Kit
S-33
TRANSISTOR MIXER, Model TM -I. A must for the Tapa
enthusiast. £11.16.6 Kit
(16.17.6 Assembled
5W HI -FI MONO AMPLIFIER. Model MA -S. A low priced
amplifier based on the S -33. Printed circuit construction makes
is easy to build. £10.19.6 Kit
(15.10.0 Assembled
HI -FI MONO POWER AMPLIFIER. Model MA -12.- Ideal
for use with Models USC -I and UMC -I, 0.1 THD at IOW. Wide
frequency range. (15.18.0 Assembled E11.18.0 Kit
18W STEREO AMPLIFIER.
Model S -99. Ganged controls.
Stereo /Mono gram. radio and tape roiligtt-
recorder inputs. P/B selection.
L38.9.6 Assembled £28.9.6 Kit *
Send for full spec. of any model S-99
TRANSISTOR RECEIVERS
"OXFORD" LUXURY TRANSISTOR
DUAL WAVEBAND RECEIVER.
The ideal domestic or personal portable
receiver. 10 Semi -conductors. Solid leather
case. Send for full details. £14.18.0 Kit
Incl. P.T.
6 TRANSISTOR PORTABLE. Model
OXR -I. Prealigned I.F. transformers.
Printed circuit, 7in. x 4in, high flux speaker.
Real hide case. Very easy to build.
Incl. P.T. £12.11.0 Kit
"MOHICAN" GENERAL COVERAGE
RECEIVER. Model GC -I U. Excellent
portable or general purpose receiver for
"amateur" or short wave listening. See full
spec. leaflets. £37.17.6 Kit
Assembled E45.17.6 GC -IU
SPEAKERS FOR YOUR OWN ENCLOSURE
12" Heavy -duty Bass (Fane 122/12) 47.7.0.
2" Tweeter (Fane 301) (3.1.6.
(both as used in the Cotswold systems).
12" Bass speaker (Audiom -51) (9.12.5.
8" Goodman's General Purpose G8 41.8.6.
Two Speakers + Cross -over, System SCM -I.
(As used in model SSU -1) with details for enclosure (S.5.0.
ELECTRONIC WORKSHOP KIT. Model EW -I. An out -
standing experimental kit for children. £7.13.6 incl. P.T.
A WIDE RANGE OF BOOKS ON ELECTRONICS AND
RADIO. PLEASE SEND FOR LISTS OR PRICES.
Many other models covering a wide range of equipment
for HOME, OFFICE or Workshop.
SEND FOR FREE BRITISH CATALOGUE
American Catalogue sent for I'- post paid
' JIIIIIIIIIIIIIIIIIIIIIIIIIIIII) IIIIIIIIIIII111111I11111111111111111111111111111
FREE
CATALOGUE of the
BRITISH HEATHKIT RANGE
Gladly sent on request .. .
HI -FI TUNERS
Model FM-4U. Tuning range
88 -108 Mc's. Tuning unit (FMT-
4U) with 10.7 Mc /s. I.F. ([2.15.0
incl. P.T.). I.F. Amp. (FMA -4U)
complete with cabinet and valves
(413.13.0). Total £16.8.0 Kit
Assembly can be arranged. FM -4U
AM /FM TUNER. Covers FM 88 -108 Mc /s. A.M. 16 -SO. 200 -550,
900 -2,000 m. Tuning heart ((4.13.6 incl. P.T.), and I.F. Amp.
(L22.11.6). Total
Send for leaflets. Assembly can be arranged. £27.5.0 Kit
EQUIPMENT CABINETS
A large range, in kit form or assembled
and finished, available to meet most needs.
Illustrated details on request. ,6
Prices from £8.8.0 to £46.4.0
PUBLIC ADDRESS AMPLIFIER,
PA -I. 50 w. Amplifier, two heavy duty
speakers, variable Tremolo. Ideal for
use with guitars, etc. £54.15.0 Kit
(74.0.0 Assembled
Legs optional extra 17'6. Set of 4.
SO W POWER AMPLIFIER, MA -50
Ideal for PA work, electronic organs etc.
¿27.18.0 Assembled £ 19.18.0 Kit
STARMAKER '33. Transistorised PA /Guitar Amplifier.
All transistor circuit gives full 20 watts r.m.s. output. Two heavy
duty 12" speakers, Tremolo. Compact size 18" x 29" wide x 10'
deep. Kit 444.19.0. Assembled 459.10.0 available shortly.
To DAYSTROM LTD. Dept. P.W. -12, GLOUCESTER ENG. I
Please send me FREE BRITISH CATALOGUE (Yes /No) I
Full details of model(s)
NAME
ADDRESS
-------
aasa
www.americanradiohistory.com
654 PRACTICAL WIRELESS December, 1965
10
12
R & TV
1.
2.
e VALVE 15 WATT PUSH -PULL AMPLIFIER, 15 x 7 1 1 #fn. A.C.
Mains 200-250 volts. 4 inputs with controls for same and bass and
treble lift controls. Tapped for 3 and 15 ohm speakers. Extra H.T.
and L.T. for F.M. Toner aupplies etc.. built and tested. 7 gm. P. & P.
13/6.
CYLDON AM FM PERMEABILITY TONERS FOR ALL TRANSISTOR
OPERATION. Size 2; x 21in. approx. By famous manufacturer. A.M.
1.F. 470 Ho ¡e, F.M.-I.F. 10.7 Me /s. A.M. coverage from 1620 ¡Kc /, -5.25
Kc /e. F.M. coverage 108 Mc /4- 88Mc /s. Circuit diagrams 216. FREE
with Tuner, 1st, 2nd and 3rd A.M. I.F.'e, let, 2nd, 3rd and 4th F.M.
I.F.'s V.H.F. Oso. choke, A.M. I.F. trap. All the above are the R.F.
end of an A.M. /F.M. receiver or radio etc. The above Items 22.I0.0.
3. AMPLIFIER HIT. 3 to 4 watt Amplifier Kit. Comprising chassis 81 x
21 x lin. Double wound mains transformer, output transformer,
volume and tone controls, resistors. condensen etc. Valves 6t'8.
ECC81 and metal rectifier. Circuit 1 /6. free with kit, 29/8 plus 4/6 P.61'.
4. 8- 9 T 6 VAL ¡VE PUSH-PULL AMPLIFIER a &METAL RECTIFIER
FIER.
r L.P. records, musical instruments, all makes of pick -ups and mikes.
Output 8 watts at 5 per cent total distortion. Separate bass and treble
lift control. Two inputs, with contrele for gram. and mike. Output
transformer tapped for 3 and 15 ohm speech coils. Built and tested.
28.19.6. P. A P. 8 / -.
6. 40W FLUORESCENT LIGHT HIT incorporating GEC Choke size 81 x
li x lain. 2 bi -pin holders, starter and starter holder. 11/8, P. A P. 4;6.
GEC choke
size
Similar to x Il a 11in.W bin- pin ss. starter
and starter holder,
i older 17/8.
P. A P. 5/6.
8. OSCILLOSCOPE for D.C. and A.C. APPLICATIONS. Push -pull X
amplifier: Fly -back suppression; Internal Time -base Scan Wave form
available for external use; pulse output available for checking TV line
O/P Tranformere, etc. Provision for external-1 /P and C.R.T.
Brightness Modulation. A.C. mains 200- 250v., 218.18.0. P. R P. 10 / -.
FULL 12 MONTHS'. GUARANTEE INCLUDING VALVES and TUBE.
7. FIXED FREQUENCY SIGNAL GENERATOR. Crystal controls in metal
ease, size 10 z 6 x bin. Incorporating two FC13 valves. mains trans-
former, r
metal rectifier. choke, indicator lamp, crystal
components. Modulated and unmodulated output socket. Originally
used for I.T.V. frequencies. Brand new. 89/6, plus 71- P. A P. A.C.
mains 200 -250 volts.
SILICON RECTIFIERS. 250v. PAN., 750mA. Six for 7/8 poet paid.
S. SencHET MULTI-METER.
0 S 3
21 1 fin
0 O.P V. on both A.C. and D.C. A.C. and eD.0 volts.
0 -15, 0 -150, 0- 1,000. D.C. current 0- 150mA. Resistance 0 -100k O.
FREE GIFThfer limited period only. 30 )watt Electric Soldering Iron
value 15/- to every purchaser of the Pocket Multi- Meter.
8, CHANNEL TUNER
Valves rrequired 9 PCF80 and PCC84 from 174.
Cover
BBC and ITA ranges. Also Police, Fire and Taxis, etc. Brand new
by famous maker, 10 / -, P. A P. 3/ -.
10. POWER SUPPLY HIT in metal case. size 31 e 21 x 210. incorporating
maire transformer, rectifier and condensers. 230/250 A.C. mains
Output; 9v.. 100MA. 10/6 plue 3/- F. A P.
11. B.S.R. MONARCH 0A14 WITH FULL FI HEAD, 4- speed, plays 10
records, 12in.. 101n., or 7in. at 16. 33, 45 or 78 .p.m. Intermixes
7in., loin. and 12in. records of the same speed. Has manual play
position; colour brown. Dimensions: 121 x 101in. Space required
above baseboard 41in., below baseboard 21ín. Fitted with full Fi
turnover crystal head. 26.19.6. P. & P. 7/6.
12. FIRST QUALITY PVC TAPE
51in. Std. 850ft. 9/- Sin. L.P. 850ft.
7in. Std. 1200ft. .. 11/6 3in. T.P. 80ft.
3in. L.P. 240ft. .. 4/- 5in. T.P. 1800fí.
51in. L.P. 1200ft. .- 11/6 51ín. T.P. 2400ft.
L.P. 1800ft, 18/6 7in. T.P. 36001).
P. & P. on each 1 /6. 4 or more Post Free.
18. MAYFAIR 5- TRANSISTOR TAPE RECORDER
Capstan -driven, battery operated, 71 and 31 i.p.s. Precision made.
Push -button controls. High quality 211n. speaker. Push -pull circuit.
Output: 400 mw. Frequency response: 200 -7,00 kc /s. Fast rewind.
Up to 1 hour twin track playing time. Automatic erasing for re.
recording. Dimension: Sin.: llin. x 31in. Weighs only 71b. 211.11.0
plus 716 F. & P.
14. HMI TAPE DECK
AC 200/250v. tape speed 31 twin track, 25.6.0 P. A P. 7/6.
15. GEC FLAT HEATER ELEMENT 500 w.
Can be used for wash boilers, washing machines, etc. Five or six ele-
ments can be used in parallel to give 250/300 watts. Size 51 a 11,
copper enclosed. 2/6 each. P. & P. 1/-. 4 or more Post Paid.
10,6
10 /0
25/0
82/6
42/6
RADIO & T.V. COMPONENTS (ACTON) LTD.
21b High Street, Acton, London, W.3.
All enquiries Stamped Addressed Envelope.
Goods not despatched outside U.K.
Shop hours 9 a.m. -6 p.m. Early closing Wednesday
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 655
COMBINED PORTABLE & CAR RADIO
4in, SPEAKER The Radio with the STAR features
* 7- transistor superhet. Output 350mW.
* Grey wooden cabinet, fitted handle with silver
coloured fittings. Size 12+ x 84 x 3fin.
* Horizontal tuning scale, size I I; x 21in. in silver
with black lettering.
* All stations clearly marked.
* Ferrite -rod internal aerial
* I.F. neutralisation on each
stage 460 kc /s.
* D.C. coupled output stage
with separate A.C. negative feed back.
* All components, ferrite rod and tuning
assembly mounted on printed board.
* Operated from PP9 battery.
* Full comprehensive instructions and * Fully tunable over medium and long waveband.
point -to -point wiring diagrams. * Car aerial socket. Full after -sale service.
* Printed circuit board, back printed with all component values.
All enquiries Stamped Addressed Envelope.-1
ONLY £4.4.O
Plus 616 P. & P. Parts
list & circuit diagram
2/6. FREE with parts.
SPECIAL OFFER -POWER
SUPPLY KIT to purchasers of
"Elegant Seven" parts, incorporating
mains transformer, etc. A.C. mains 200 -250v.
Output 9v, 50mA. 716.
RADIO & TV COMPONENTS (ACTON) LTD 2IC High St., Acton,
Open 9 a.m. -6 p.m. including Sots. Early closing Wed. Goods not despatched outside U.K.
London W3
Terms C.W O.
FREE T - THE LATEST EDITION OF ENGINEERING. OPPORTUNITIES
Have you sent for your copy?
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is a highly informative 156 -page guide to
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656
THE "SKYROVER" RANGE
PRACTICAL WIRELESS December, 1965
Offer the Finest Value and
HOME CONSTRUCTORS
We consider our construction parcels to be the finest value on the home construc-
tor market. If on receipt you feel not competent to build the set, you may return
it as received within 7 days when the sum paid will be refunded less postage.
GENERAL SPECIFICATION
7 transistor plus 2 diode superhet, 6 waveband portable
receiver. Operating from four 1.5 v, Loch batteries.
The SKYROVER and ShortnWavebancover 1 -941 M
and also 4 separate switched band- spread ranges. 13M,
16M, 19M and 25M, with Band Spread Tuning for accu-
rate Station Selection. The coil pack and tuning heart
is . completely factory assembled, wired and tested.
threeremaining rm our easy Lob òllow
completed
tage in y stage
instructions.
A simple additional circuit
11ÓÓ /1á950M, coverage
a (ncluding
1500 M. Light programme).
Al) components and de-
tailed construction data.
Only10/-extra F:.7(
This conversion Is suitable
for both models that have
already been constructed.
NEW -The SKYROVER Mk Ill
Now supplied with redesigned cabinet, edgewise
controls, black and chrome plastic cabinet. Post
Size 10 x 61 x 311n. with carrying handle. el19.g
('an now be built for
H.P. P. Price
Terms: 27/- dep and ll months at 15)9. Total
The SKYROVER DE LUXE
Tone In a wCircuit o abinetincorporated
size, 19 x 6} x lin.,scoverred
Data for Receiver 2/6 extra. with a washable material with plastic trim and carrying
Refunded if you purchase the handle. Car aerial socket fitted.
parcel. Four U2 batteries */3 Can now be built fora H.P. Terms: 3a3)- -19/2.
extra. All components available Post 5,- £10.19.6 aotal R.P.P. at 19)2.
separately. STOP PRESS ITEM!
The Very Latest MAGNAVOX -COLLARO 363 TAPE DECK
3 Speed model -11, 31, 71 i.p.s., available with either i track or I track heads. Features
include: pause control: digital counter; fast forward and rewind; new 4 pole fully screened
induction motor; interlocking keys. Size of top plate 131 x llin. x 51ín. deep below unit
plate, For 2001250v. A.C. mains, 50 c.p.s. operation. New. unused and fully guaranteed
LASKY'S PRICE with } track heads £10.10.0 pacffinge 7/6
LASKY'S PRICE with }track heads £13.19.8 extra
LIMITED STOCKS: COLLARO STUDIO TAPE DECKS
200/250v. A.C. mains, 50 c.p.s. model -with } track heads 210.10.0: with } track heads
213.19.6. Carriage and packing 7/6 extra.
ELIZABETHAN LZ27 PORTABLE TAPE RECORDER
Special Bargain Offer -brand new, unused and fully guar-
anteed. Brief specification: 2 speeds -7i and 34 i.p.s.: 2
track; 31 watt output; inputs for mic. and radio; outputs
for ext. speaker and additional amp. or monitor; built in
7 x 41n. speaker; tape position and record level indicators;
fast forward and rewind. Volume and tone controls also
superimpose facilities. Takes 7in. spools. For 200/250v. A.C.
mains. Attractively styled cabinet with carrying handle
m i detachable
tape an empty spool 1 Maker's Complete Price 27 Gnsl
LASKY'S PRICE 18 Gns. and Packing 10/-
B.S.R. AUTOCHANGERS-BRAND
REVER PR ICES EW
Brand new and fully guaranteed -complete with cartridge
and stylus.
ÚA14 4 speed mains model
ÚA16 4 speed mains model
UA16 9 v. battery model
ÚA20 4 speed mains model
Add 5/- carriage and packing on each
£4 9.6
£4.19.6
25.19.6
25.19.6
SPECIAL OFFER! GARRARD AT5 AUTOCHANGERS
4 mains model -brand new and fully guaranteed.
LASKY'S PRICE with mono crystal cartridge
LASKY'S PRICE with stereo cartridge
£5.19.6 carriage n
£6.9.6 5 p!- a exckitrg a.
INTERNATIONAL TAPE Famous Amoebae Brand -Fully Guaranteed
81n. Message tape, 150ít. 8 54in. Ling play. 1.20011., Acetate base .... 12
Sin. Message tape, 225ít 4 1 54in. Standard play, 850ft., PVC base ..., 11
Sin. Message tape, 300ft. 7 51in. Triple play, 2,400ft., Mylar base .... 45
S }in. Triple play, 600ft., Mylar base 15 7in. Standard play, 1.200ft., Acetate base 10
On. Triple play, 900ft., Mylar base 17 7in. Standard play, 1,200ft., Mylar base .. 12
lin. Double play, 1,200ft., Mylar. base 15 7in. Long play. 1,800ft., Mylar base 19
An. Long play, 900ft., Acetate base 10 71n. Double play, 2,40011., Mylar base .... 25
Sin. Standard play, 600ft., PVC base 8 7in. Long play, 1,800ft., Acetate base .... 15
Ilse. Triple play, 1,800ft., Mylar base 85 7in. Triple play, 3,600ft., Mylar base .... 58
: }in. Double play 1,800ft., Mylar base , 22 P. & P. 1/- extra per reel; 4 reels and over Post Free
The "REALISTIC" Seven
* 7- transistor Superhet. * 350 milliwatt
output into 41n. high flux speaker.
* All components mounted on a single
printed circuit
board. Full mad-
turn and long wave
cover. * Plastic
cabinet with carry-
ing handle, size
7 x 10 x 38ín Blue/
Grey or all Grey. --- ---
* Socket for car
aerial. * I.F.
frequency 470 Kc /s.
* Ferrite rod
internal aerial. Operates from PP) or
similar battery. * Full data supplied
All coils and I.F.'s etc. fully wound ready
for immediate assembly. Any outstanding
(An be built for f 6
receiver. .19. 5 Li V
Post 4/6.
PP9 Batt. 3/9. Data and Instructions
separately 2/6. Refunded if you purchase
the parcel. All parts sold separately.
REALISTIC Seven DE LUXE
With the same specification as standard
model -PLUS a superior wood cabinet
in contemporary styling with full vision
circular dial. ONLY £1 EXTRA
GOODMANS OF ENGLAND
CROSSOVER UNITS
X111750 HALF SEITION CROSSOVER.
For use with bass and treble speakers. 1511
imp. to crossover at 750 c.p.s. Rated at 25
watts (British). In wood case 61 x 4} x 4in
New and unused.
LASKY'S PRICE 29/- 2/°6! t
STEREOPHONIC FILTER. This is a
frequency divider /mixer for use with a
Stereo amplifier. Its function is to combine
the bass frequencies up to 300 c.p.s. into a
single bass speaker for both channels and to
divide the frequencies above 300 c.p.s. into
two separate mid /top range speakers. It can
also be used as a 300 c.p.s. crossover for a
mono system. 1511 imp. Rated at,25 watts
(British). In wood case 10 x 41 x 3in. New
and unused.
LASKY'S PRICE 19/6 2 fist
SINCLAIR MINIATURES
We stock the complete range of Sinclair
Super -miniature Kits.
THE MICRO -6 pocket radio 59/6
THE SLINLINE pocket radio 49/6
THE X-20 Amplifier £7.19.6
Ready bu It and tested 19.19.6
'111E X -10 Amplifier £5 19.6
Ready Built and Tested 16.19.6
THE X-20 Amplifier 27.19.6
Ready built and tested 1,9.19.6
See our Practical Wireless November '65 adver-
tisement for fuller details.
U.H.F. TUNERS
Only a few available. Complete
with PC86 and PC88 valves. We
regret no circuit or data is avail-
able. Knobs included.
LASKY'S PRICE 7,9/i6 ii.
ost
GORLER UT 340 FM/VHF
TUNING HEART
Permeability tuned -covering 87 to 108 Mcls.
For use with one ECC85 valve. In metal case.
size 3 x 21 x 11in. Circuit supplied.
LASKY'S PRICE 19/11
ECC85 valve 91- extra.
LASKY'S FOR D.I.Y. CONSTRUCTION BARGAINS
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
Service in Great Britain to both
& HI -FI ENTHUSIASTS
TAPE RECORDERS . RECORD PLAYERS . AMPLIFIERS ETC.
COMPLETE MONO STEREO SYSTEMS TO YOUR SPEC.
NEW COMMUNICATION
RECEIVERS
MODEL KT 320 KIT
Supplied to sub- aeeeoebliee for easy building. Covers
range From 640 %c /s to 30 Mc /s. Ham Band is pro-
vided with a scale for direct reading and can also be
band spread, 9 valves. Facilities: A.N.L.. A.V.C. and
M.V.C. Q Multiplier also serves as B.F.O. H.F. stage
snd two LF, stages ensure high sensitivity and
selectivity (all coils and I.F.. are supplied pre.
aligned,. 2 Aerial Sockets. Stand -by position for
use with a transmitter S meter fitted. 200 -260v, A.C.
mains. Steel cabinet, grey crackle finish. Size
15 x 8 r 10in. Dial 12 x din. All parts new and fully
guaranteed. Complete with full construction data
and operating manual.
LASKY'S PRICE 25 GNS.
Also available ready ballt end tested 29 ene.
H.P. Terms available.
POST
MODEL HE30 gt'1 a few avallable-
ae odvertieed June '60.
LASKY'S PRICE 33 GNS.
H.P. Terms available.
MODEL HE40
Covers medium wave band and 1.6-4.4 Mo /s., 4.8-
11.0 Mc /a, 11.0 -30.0 Mc /e. in separate switched
band epread wages Controle Include B.F.O. Sensi-
tivity, A.N.L. Receiver- dtandby Switch, Tone
Switch, S- Meter. For 300.250. A.C. /D.C. Internal
loop and telescopic antennae fitted. Valve line -up:
125E6, 12ßA8, 12ÁV6, Seel. and metal rectifier.
Sine 131 z 8f z 51 in. Instruction mapual included.
No Kite available.
LASKY'S PRICE 19 GNS.
H.P. Terms 84.0.0 dep. and 11 months at 11.12.0.
Total H.P.P. 221.12.0.
MODELHE80 14- °a°° a'll'er sensitive
communication receiver.
trcq. range 540 Keis -30 Mc/s. and 144.148 Mc /a.
Dual conversion on 2 metres, with extra R.F. stage.
Single R.F. stage, two LF. stages on all other banda.
B.F.O. and Q- multiplier circuits. Improved Á.N.1.
and voltage regulated powerpack. " it meter
band spread on amateur bande, large illuminated
egging scale. All controle fitted. Output
for speaker and phones. Valve line-up: 4 z BAQS,
3 a 6ßA6, 2 x 8ß26, 1 z 8BL8, BALD, SAQ6, 6CÁ4.
and OA2. Steel case 17 x 71 x IOin. For 200/220v.
A.C. mains. Brand new won foil iootructlon manual.
No K ;t+ available.
LASKY'S PRICE 59 GNS. R$1.
H.P. Terms 212.19.0 dep. and 11 monthly payment§
of 24.18.0. Total H.P.P. 288.17.0.
657
LASKY'S'
The "Sixteen" Multirange METER KIT
This outstanding meter was featured by Practical Wireless In
the Jan. '64 issue. Lasky's are able to offer the complete kit
of parts as specified by the designer.
RANGE SPECIFICATION: D.C. volts: 0- 2.5- 26- 50- 250.500 at
70,000 0/V A.C. volts: 0- 2.5.50 -250 -500 at 1,000/ 0 V. D.C. current:
0-SOt1 -A. 0-2.5-50-250 MA. Resistance: 0.2,000 0. 0 -200 0. 0 -20M 0.
Basic movement: 41)µA f.s.d. moving coil. Black plastic ease,
31 x 51 x llln. Controls: 12 position range switch: separate slide
switch for A.C. volts -D.C. ohms; ohms zero adjustment pot.
meter; meter zero. Complete with all parts and full construction
details. Data and circuit available separately, 2/6 refunded If all
parts bought. Pair of Batteries, 2/5 extra. H.P. terms avallable.
LASKY'S PRICE £5.19.6 & P.
THE LATEST ''KUBA"
b1111111:''
IMPORTED AM FM
STEREO RADIOGRAM
CHASSIS
long medium and short waveband cover-
age plus VHF/FM. Piano key wave.ebange-
Separate flywheel tuning on AM and FM
bass, treble and balance controls Magic -eye
tuning indicator. Perrlto rod aerial. The
very latest printed circuitry. Provision
for multiplex-adaptor. 6 valves-line up; ECC85, EC11801, ECC83, ELLMO, EAF801. Full vision tuning
scale. sise 21 a Bin. Overall dimenefona: 21 a 81 z 81n. Made to the very highest etandarde.
LASKY'S PRICE 292 GNS. carriage & Insurance 12/6 extra.
TEST METER ADAPTOR
Type P.E. 220. Transistorised device which enables any 50 microamp D.C.
Multnneter to be used in place of a valve volt meter. On the Iv. range an
impedance of 1 megohm is offered which increases on the 100v. range to
100 megobms. 7 rangea Immediate connection to Ave 8 but visitable for me
with any other 60 microamp meter. Size 8 z 6 z Sin. New and boxed. LYS
Pelee 7 Gn..
LASKY'S PRICE 39/6 Poet 2/6. Set of batteries 7/6 extra.
DOMESTIC PROCESS TIMERS BY SMITHS
Pineal quality Smith'' Clocks originally intended for use to the most expensive electric cookers. 3 typal
available-brand new and unused-at well below production cost.
Type 1. Clockwork Interval Timer. Gives loud and prolonged ringing to indicate the end of any set
time from 1 minute to 1 hour. lin. die. dial z tin. deep.
LASKY'S PRICE 9/11 Past 2/'
Type 3. A De Luxe electric clock, as illustrated, with combined sequence
switching to give automatic switching of an electric appliance to switch
on at any pre-set time up to 12 hours ahead and to switch off at any
pre-set time up to 91 hours later. Switch contacts are rated at 26 amps.
200 /250 V., 50 ewe. and are therefore suitable for cookers and heat-
ing appliances as well as tape recorders, radio., lights, eto. Easy to set.
lln. dial. Overall else 6 x 31 x 2fin.
LASKY'S PRICE 35/- ' Poet 2/6.
TRANSISTORISED BABY ALARM /INTERCOM
Two -way miniature intercom that has all the features of sets many times its sise. Battery consumption Y
exceptionally low and makes this system particularly suitable for use as a Baby Alarm. Uses one 9 e PP9.
or equiv. (approx. life 50 hours). Oleo of unite 4 x if x If in. The sturdy plastic cabinets are finished In Ivory
and cove; with chrome Stand' Lasky's price 59/6 Post 2/8
GREENCOAT RECORD PLAYER
2-speed model for :13 and 45 r.p.m. 6 volt Battery operated.
Complete with pick -up fitted with crystal cartridge. Size
only 10 a 61n. Auto stop and start. New and perfect.
59/6 P. do P. 2/8
TRANSISTORS new & guaranteed
GET SI, GET 55. GET S6, 2/6: 873A, 874P,
3/8; 0C45 0071, OC81D, 4/6: 0C44, OC70,
076, 0031 (match pair 10/8) 5/8; AF117,
0075, 0C200 6/6: 0C42. 0C43, 0073
0082D 7/6.00201.0020415 / -; 00205, 0C206
18/6; 0028 24/8.
TRANSFILTERS BY BRUSH CRYSTAL 00.
TO-01B 465 kc/s. f 2 kcfs.
TO-01D 470 kc/s, ± 2 kc/s.
TO-025 465 kc/s. ± 1 kc/s.
TO-02D 470 kc/s. t 1 kc/s.
TF-0113 465 kc/s. t 2 kc/s.
TF-01D 470 kc/s. ± 2 kc/s.
7/6 HACH
Poet 64.
207 EDGWARE RD, LONDON, W.2 Tel: PAD 3271/2 42 TOTTENHAM CT. RD., LONDON, W.I T.I:LAN2S73
33 TOTTENHAM CT. RD., LONDON, Tel: MUS 2605. 152/3 FLEET STREET, LONDON, E.C.4 Tel: FLE 2833
Both open all day Saturday. Early closing Thursday. Both open all day Thursday. Early closing Saturday.
Please address all Mail Orders to Dept. X.W 207 Edgware Road, London, W.2.
LASKY'S FOR SPEEDY MAIL ORDER SERVICE
www.americanradiohistory.com
658 PRACTICAL WIRELESS December, 1965
NEW! NEW! Just published end of October
TAPE
RECORDER
SERVICING
Packed with concise
servicing data and facts for
day -to -day use ...
the 'gen' at
your fingertips
in one
authoritative
volume !
MANUAL
Tape recorders present special problems to the service
engineer. Many decks are quite complex mechanically, whilst
high performance is required of the associated electronic
circuitry. The best aid the service engineer can have in dealing
with recorders is adequate information. This book provides
concise service data, including
A book to save circuit diagrams and numer-
you time and ous layout diagrams and views
of mechanisms and ad-
make you profit justments, for the
majority of
tape recorders and decks that have been
released in this country. The notes are
compiled partly from manufacturers' official
data, from trade sources, and also from bench
notes and observations made by the author in
the course of a number of years' practical
servicing. Also contains an authoritative
introductory section on the principles
and practice of tape recording, practical
repair procedures, and microphones
and matching.
Covers 282 models
in 344 pages
supported by over
345 drawings,
exploded views and
circuit diagrams
Published by
NEWNES_
by H. W. HELLYER
A.M.T.S. A.I.P.R.E., A.M.I.S.M.
Alba, Allegro, Amplion, B.S.R., Baird, Brenell,
Bush, Butoba, Collaro,
Cossor, Dansette, De-
fiant, Dynatron, E.M.I.,
Editor, Ekco, Eliza-
bethan, Elpico, Elpico-
Geloso, Ferguson,
Ferranti, Ferrograph, Ficord, Fidelity, G.B.C.,
G.E.C., Garrard, Geloso, Gramdeck, Grundig,
H.M.V., Hagen, Kolster- Brandes, Korting,
Magnavox, Motek, Murphy, Peto- Scott,
Philco, Philips, Playtime, Portogram, R.G.D.,
Recording Devices, Regentone, Robuk, Simon,
Sobel!, Sonomag, Sony, Sound, Soundmirror,
Steelman, Stuzzi, Telefunken, Thorn,
Truvox, Ultra, Verdik, Volmar, Walter,
Winston and Wyndsor.
Makes covered
from 63
Manufacturers
include..
rom your bookseller, or:-
POST FORM TODAY! NO SALESMAN
WILL CALL
To: Odhams Books, Dept. S.F.3, Basted, Sevenoaks, Kent.
Please send me, WITHOUT OBLIGATION TO PURCHASE, "Tape
Recorder Servicing Manual ". I will either return the book in good condition,
carriage paid, within eight days, OR send down payment of 191- eight days
after delivery, then five monthly instalments of 10 /- each. ALTERNATIVELY,
I will send cash price of 63/- plus a small postal charge eight days after delivery.
Delete words NOT applicable: I wish to pay CASH /BY TERMS. 1 am
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BLOCK LETTERS BELOW
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The book that can repay its
purchase within a few hours
www.americanradiohistory.com
B.T.H. TAPE MOTORS 113 v. A.C.I
20 w. 12/8 pair. for 200 -260 V. (in sertes)
December, 1965 PRACTICAL WIRELESS
DESPATCH- TODAY ? -PHONE- R.C.S.!
NEW ELECTROLYTICS FAMOUS MAKES
TUBULAR TUBULAR CAN TYPES
1/860v 2/- 100/25. 2/- 8 /800. 9/-
2/350v 2/3 . 250/25v 2/8 18 /800. 12/-
4/360v 2/3 500/15v 2/8 10+ 16/500v 7/8
8/460. 2/3 1,000 /15v 2/6 32 +32/850. 5/6
8 +8 /460v 3/8 82+22/450. 8/-
50 + 60/350v 7/-
84 +120 /350v 11/8
100+200/275. 12/-
DE -LUXE RECORD PLAYER KITS
A atochange 2 -lone
Cabinets 17 x 15 x
81in. High flux
loudspeaker, 8 watt
2 valve 2 stage
amplifier ready built.
Quality output. Volase
and Bas. controls. All
items at
together
perfectly.
Special in-
Itrnetmns
enable as-
sembly in
30 minutes
only 6 wires
to jein. 12
months guarantee.
AUTOCHANGE KITS Complete -ae above.
B,9.R. Monarch £10.10.0 P,P. 7/8
Garrard "1000" 211.19.8 P.P. 7/6
Garrard AT5 £12.10.0; ATe £14.5.0. P.P. 7/8
OR SEPARATELY
Cabinet with board 14 x 18m. £3.9.8 P.P. 5/8
Amplifier with speaker £3.12.6 P.P. 3/8
AUTOCHANGERS (Stereo 10/- extra)
B.OB. DAYS or ÚA14 Mono £5,19.8 P.P. 3/8
Garrard "1000" Mono 28.10.0 P.P. 3/8
Garrard AT5 28.10.0; AT6 110.10.0 P.P. 5/8
SINGLE PLAYERS
B.S.R. GU7 auto stop 14.17.6 P.P. 2/6
RSA. Junior with lep. P.U. 19.7.6 P.P. 2/6
Q MAX CHASSIS CUTTER
Complete die punch Allen screw and key
;tn. 1416 It}in, 181. 1tin. 2216
in. 14/9 !kin. 181. tin. 34/3
lin. 1516 /tin. 1816 2341 in. 37/9
-in. 1519 I'?in. 201. 2 4in. 4413
lin. 181- )kin. 20/6 lin. sq. 31/6
CRYSTAL MIKE INSERTS
1 1in, dia. x lin.. 6/6; BM8 1 x }in.. 7/8;
ACOS MIC. insert 111n. die. x }ln.. 8/8
TANNOY CARBON MIKE complete, 5/6
Coils Wearite "P". 4/ -; Osmor "Q" frr4a 4/ -.
Rep. DRR2 L. & M. with reaction, 4/8.
Ferrite Aerials Valve. M. 8/9: M.L., 12/8.
Ferrite Aerials. L.M. transistor /circuits.
OSMOR, 10 / -. R'EYRAD, 12/6.
Ferrite Rod 8 211n., 6xa41n, 6 x a /tain 3/- ea.
H.F. Choke,, 4/8. pr. Osmor QC1, 6/8.
Test Prods, 2/9. Set Trim Tools, 3/.
Neon Mains Tester Screwdriver, 5 /..
MWtieore Solder, 6d. yd. Dispenser, 2 /6.
PW TAPE RECORDER TUNER
All components specified Eagle H402 transistor
coils. 3 455 ko I.F.e and oscillator coil, tuning
condenser with trimmers, ferrite aerial, Tuning
dial, Mallard tramiators and power pack compo-
nents, 13.15.0. Eagle 00402 coil set only, 24/6.
MOVING COIL MULTJMETER TK loa
0- 1000v. A.C. /D.C. ohms 0 to 100k, etc., 49/6.
VALVE HOLDERS. Int. Oct. ed. Maeda Oct. M.
B70. B85., 880, BOA, 9d B70, BOA Cans, '1/ -.
Ceramic 1.0. EF60, 807, BOA, 1/ -. Valve plugs 2/3
I.F. TRANSFORMERS 7/6 pair
465 K/s Slug Tuning Miniatore Can, 8 u 1 }in. dia.
High Q and good bandwidth. Data Sheets,
New R.C.S. VALVES 90 day Guarantee
IR5 8/-6Q711 et- E13/241 8/-'PCL54 5/-
185 8/-68\7 5/-EBCBl 6/-PL01 10/-
114 3/-6V6G 5/-EBF80 6/-PL83 9/-
384 7/-8X4 8/-ECH42 9/- PY80 7/-
354 7/- 6X5 8/- RCH8I 9/- PY81 8/-
5114 8/- 12AT7 6/- ECL80 9/- PY82 7/-
5E3 6/- 12AU7 6/- ECI.82 10/- 81.61 8/-
5Z4 9/-11AX7 7/-EF162 7/. U12 7/-
6856 4/- 121E7 5/. 2E183 7/- UBC41 S/-
6AT8 6/- 12K8 14/. EF88 10/- UBCBI 6/-
6BA6 7/- 12Q7 71- EPOS 8/- UBF89 5/-
6BE6 5/- 35133 9/- ELS4 7/- UCA81 9/-
SAS 3/- 35Z4 5/- F.V51 9/- UCL82 10/-
6J5 5/- 951 2/- E 1(86 91- EF89 5/.
6J6 5/- DA1-96 8/- E'L40 5/- EL41 9/-
6271; 8/-D1096 8/-EZe0 7/-UY41 6/.
BKB 5/- DK96 8/- RZ81 7/- UY85 7/-
8117G 8/-DLO6 8/-MU14 7/. 111.79 7/.
BK86 0/-NABCAO 5/- PC97 7/. VR150 ^/-
65731 6/- EH91 4/- PCC84 8/- W8] 6/-
RETURN OF POST DESPA ICH
18/450v á/-
32/460v 8/9
25/26. '1/9
60/60, 2/-
8+18/450. 879
16 +18/450. 4/3
82 +32 /SSOv 4/6
PAPER TUBULARB
860.. 0.1 9d4 0.5 1/9; 1 mFd, 3 -; 2 tnF'd, 150v. 3 / - -'
500v. 0.001 to 0.05 9d,; 0.1 1 /-; 0.25 1 /6; 0.5 2/8.
1,000v. 0.001, 0.002, 0.005, 0 01, 0.02, 1/8; 0.05.
0.1, 2/ -; 0.25, 0.5, 8/ -.
2,000v. 0.005, 0.01, 0.02, 2/6; 0.05, 3 /6.
SuD -Bin, 0.001, 0.005, 0.01, 0.02, 0.04, 0.05, 0.1, 1/-
Sub -Min. Eleotrolytia 1, 2. 4. 6, 8, 18. 25. 30. 60.
100, 500, 1.000 mFd. 15 volts, 2 /6,
SILVER MICA /tolerance 1pF), 2.2 to 47pF, 1 / -I
ditto 1% 50 to 800pF, 1 / -; 1,000 to 5,000 6F, 1 /9.
CERAMICS 500v, 1pF to 0.01 mild., 9d each.
TWIN ,.ANGE. "0.O" 208 pl' + 176 pF, 10/8; "O"
365 pF min., 10/ -; 500 pF standard with trimmers
9/8; midget with trimmers, 9 / -; 500 pF slow wodon,
standard, 9/ -; small 2 -gang 500 pF. 19/9. Single
"0" 365 pF, 7/6 SHORT WAVE. Single In pF",
26 OF. 60 pF, 75 pF, 100 pF. 160 pF. 5/8 each.
Can be ganged together. Couplera 9d. each.
TUNING AND REACTION. 100 pF. 300 pF, 500 pF,
8/6 each, solid dielectric. TRIMMERS Comp -sexton
ceramic, 30, 50, 70 pF, 9d., 100 p5', 150 pF, 1/8;
205 pi', 1 /6; 600 pF, 750 pi'. 1 /8.
HEADPHONES. 2,000 ohms. 12/8; 4,000 ohms, 15/ -.
EL24 Transformer De Luxe, Posh Pull, 30w., 90/ ,
ELM Ultra Linear Posh Pull, 10w.. 49/6.
10w. Menti -ratio Push Pull. 18/6.
Standard Pentode 5/6. Mis. bal. o-p trans 6/9
TRANSISTOR MAINS
ELIMINATOR PP1 -6v. PP9.9v. 2916
DOUBLES 42/6. PP1+PP1, PP9 +PP9, PP11
(4 4 ; +4 ;1. Sine as batteries. Also min. 9v. 19/6.
WEYRAD PSO COILS
Ferrite aerial 12/6. Ow. P50 /1AC, 5/6; 1st
P5Ó /3CC P; P0ri/v2CC Tr /ans LFDT4, 9/6;
Printed Circuit 9/6; 35 ohm Speakers, 51n.
17/6; Ox4in. 21/ -. Book 2/ -. 3 ohm OPT 10 /8
NEW MULLARD TttANSISTORS
Holders 1/3; 0071, 6/ -; 0072, 7/6; 0Á210, 9/8;
OC81, 7/8; AFllb, 10/6; AF114, 11 / -; 0044, 8/ -;
0045, 8 / -; 00171, 9 / -; 0C170, 8/6; ÁF117,
9/8' OA81 SI - 0128, 12/8; BY100, 10 /..
SILICON RECTIFIERS. 0A210 400mA, 400v. 5/6;
ORPI2 (photo electric) 12/8.
MAINS TRANSFORMERS Postage 2/- each
STANDARD 250 -0.250 80mA, 6.3 y. 3.5 a
tappe 4v. 24, 22/8 ditto 350 -0.350. 29/6
'25.,
MINIATURE 200v.. 20mA., 8.3v., Ia, 10/8
MIDGET 220v., 46mA., 6.3v., 2a. 15/8
SMALL 300 -0.300 70mA., 6.3v., 4a. 19/6
E.M.I. 260 -0 -200, 100mA, 6.3v. 3.5a, 5.3v, 11a 17/-
HEATER TRANS. 6.3v.. Ila.. 7/9; 6.3e. 4a, 10 /6
Ditto, tapped 1.4, 2, 3, 4, 5, 0.25., 1 }a. 8/8
GENERAL PURPOSE LOW VOLTAGE 2 amp.
3, 4, 5, 6, 8, 9, 10, 1ss2, 15. 18, 24, 30v. 22/-
AUTOTRANBFO pp
RMERB C tape up to 60, 29 ¡8
0.115, 200, 270, 241/v., I50w, 22/6; 500w., 82/8
MULLARD "510" Mains Transformer 88/6
TRANSISTOR, 9v., 80mA., li x II x lin. 7/8
nRl-í15M
RECORDING TAPES
LP Sin. 591111. 11/6: DP 120010. 19/6
LP 5iin. 120011. 14/6: DP 18001 t. 24/6
LP 71n. 1000f1, 19/6: DP 2400ft. 29/6
Volume Controls ! 80 CABLE COAX
Linear or Log Tracks i semi -ati paced lis.
Long opiudles. Midget 40 yds. 17 /6. 6d d.
6 K clime to 2 Meg 60 yds., 25/ . y
L.B. 3/.. D.P. 4/8 Ideal 625 dues C.D.F
Stereo LIB 10/8: DP. 14/6 Low loss 5,111
lm log . lm A log. 716 100ft. 50,1 Mc,al /Byd.
TELESCOPIC CHROME AERIALS. 12 to 3341., 6/8
TRIPLEXERS Bands I, D, ID. 12/6 COAX PLUGS 1/-
LEAD SOCKETS, 2 / -; PANEL SOCKETS. 1 / ,
OUTLET BOXES (Surface or flush), 4/- each.
BALANCED TWIN FEEDER. 66. yd., SO or 300 ohms
TWIN SCREENED. 1/- per yard, 80 ohms only.
THE "INSTANT" BULK TAPE
ERASER AND RECORD HEAD
DEMAGNETIZER 200/250.. A.C. 351.
659
BAKER LOUDSPEAKERS
HIGH FIDELITY
MODELS
12íu.. 15w., STALWART
3 or 15 ohm. 45- 13,000
c.c.s., 12,000 tines. Basa
res. 45 c.p.s. 5 ens.
12in 15w DE LUXE
Foam Cone Surround.
25- 18.000 c.o.s.. 14,000
Imes. Baas res. 35 c.c.s.
0 gas.
121n 20w., SUPER
Aluminium Drive. Foam
Cone Surround 20- 20,000
o.n.o., Bass rea. 22 c.p.e.
10 gas.
NEW GROUP MODELS
For Bass, Lead and Rhythm Dollars.
Bass res. 80 c.o.s.. response 20- 10,000 c.p.e.
Voice coils 15 ohms for 8 ohms to orden.
"GROUP 25" 12in. dia., 25w.. 12,000 lines 5 guau
"GROUP 35" 12in die.. 35w. 14,000 linea 81gm.
"GROUP 50" 15in. dia., 50w., 17,000 linea 18 gm.
LOUDSPEAKER CABINETS. It exine coy ered
17 a 15 x /05., 58/8; 16 x 12 x 4iu., 39/8.
LOUDSPEAKERS P.M. 3 OHM FAMOUS MAKES,
211n.. 3it,., Ain., bin., 7 x 4m., 15/6 each; sin 17/8;
61m., 18/8; loin., 30 / -: Ilis.. 30/ -; (I5 ,dens, 35/ -1;
10 x bin -, 22/6; 8 x 3m.. 21/ -; 0 x sin., 21/ -.
EMI 13 x sin, 1038' ceramic, double cone. 45/ -.
WAVE -CHANGE SWITCHES, '2 p. ?way or 2 p.
ti -way: 3 p. 4 -way or 1 p. 1.2 -way; 4 p. 2 -way or 4 p.
3-way, 3/6 each; s p. 4 -way, 2 wafer, 6/6.
WAVE -CHANGE "MAKITS" available. 1 p. 4O.wa,.
2 p. 6 -way, :1 p. 4 -wa3 4 p. 3 -way, 6 p. 2- at. Kit -
Price, 1 water 8/8; 2 wafer 11/8; 3 wafer 18 / - Estee
wafers 3/8 each, extra long shafts 2/- extra.
TOGGLE SWITCHES a,p. 2/ -: 'l.p. 3/8; d.p.d.t. 4/.
*RADIO BOOKS* (P.P. 9d.)
Valves, Diodes,' Transistor equivs, 10/6
TranslstorAudloAmplitier Manual 6/-
Shortwave Transistor Receivers . 5/.
Beginners' Modern Transistor Sets 7/6
SUD- miniatureTransistorRecelvers 5/-
Boys' Book of Crystal Sets . .. 2/6
"W.W," Radio Valve Data
High Fidelity Speaker Enclosure .. 5/--
TV Fault Finding.
Milliard Amplifier Manual . . . . 816
also Guide. Books 1, 2. 3, 4 or 5 .. 5 /-ea.
Practical II MHO Inside Out .. 416
1 ' ran slstor Comm unlentlrnt Sets .. 6/-
Transistor Controlled Models .. 7/6
International Radio Stations .. 2/6
JACKS Standard open -circuit 2/8, closed circuit 4/8
t:rund,g type 3 -pin 1/3; Standard Lead Type 6/ -,
Phone Plugs 1 / -. Socket 1 / -. Banana Plugs 1 / -.
JACK PLUGS. Screened 3 / -, Grund)g 3 -pin 8/0.
BULOIN NON -REV, PLUGS and SOCKETS. P74.
2- pin 4/3; P73 3 -pin 4/6; P194 6-pin 6/6: P466 12/8.
RESISTORS. Preferred values, 10 ohms to 10 meg.
I - l I 20"x, 4d.; l; w., 8d.; 2 w., 1 /..
HIGH '
STABILITY l w., Ivá, 2 / -. Preferred value,
ln ohms to 10 meg. Ditto 2 to ohm. to 22 nieg., 9d.
5 watt 1 11.5 to B.! ohm :5 W
<
10 watt} WIRE -WOUND RESISTORS 1/9
15 watt) 10 ohms -4,800 ohms 2/-
lu K., 15 K., 25 K., 10 w. 3/.
MAINS DROPPERS Midget. With sliders. 0.3a -,
1 K., O.2a.. 1.2 K., 0.15a. 1.5K., O.la., 2 K., 8/.
each. Line ford 100 ohms ft., 3-way, 1/- ft.
Wtrewouad Ext. Speaker Controls 100 3/ -; 2.50 6/6.
WIRE -WOUND POTS 3 WATT. Pre -set Jilin.. TV
Types. All values 10 ohms to 25 K -, 3/- each. 30 K
4/ -. darn,. 30K to 2 meg., 8/ -l.
WIRE -WOUND POTS 4 WATTS. Long Spindle
Value 50 nhn,. t" 36K., 8/8; 100 K., 7/8.
SPEAKER FRET 'ry;gan various colours, 32ín. wide
from 10 /- ft.: 26in. wide from 5/- ft. Samples S.A.E.
EXPANDED METAL Gold or Silver Ilt x 12. 6/.
ARDENT& TRANSISTOR TRANSFORMERS
D8085 7.8 CT.1 PushPull to 3 ohms output 11/.
D3034 1.6:1 C.T. Push -full Driver 11/-
D305811.6:1 Output 3 ohms, 11/ -; D1001, 12 / -;
D230 4.5:1 Dr .ver. 11/8; D240 8.5:1 Driver, 11/6
TRANSISTOR POTS 5 K Switched VC1546 5/3
SUB -MIN LARPIECE /Cal or Magnetic 718
SUB -MIN JACK AND PLUG 2.5 or 3.5 mm., 3/8 pr.
TV REMOTE CONTROLLER. Philips plug -Io,
with 1111 7 -way cable. 3 DP switches, dual pot,
volume and brightness. OA81 diode etc.; etc- Lot
3 Sue. New, boxed. OUR PRICE 12/8 port tree,
Blank Aluminium Chassis, 18 s.w.g, 4 sides, ew tad
corners, lattice fixing holes, 211n. sides, 7 x 41m.. 5 /6;
9 x 71n., 6/6; 11 x 71n.. 7/6; 13 a 9in., 9/6; 14 e l lm
12/8; 13 x 13,0., 15 / -; 11 áls.. 0/8.
Panel. 18 e.,e.a. 12 o I.2in., 5/6; 14 x Sin., 4/6:12 x bin
3/6; 10 x 7m.. 2/9; 4 x din., 2/ -; d x Co.. 1/6.
P.P. Charge f'6 Full list It -, C.O.D. 2'6 extra CALLERS WELCOME
RADIO COMPONENT SPECIALISTS 337 WHITEHORSE ROAD
WEST CROYDON Telephone
Written .Jarantee with ever 1665
i y purchase (Export; Send remittance and postage, no C.O.D.) Buses 133, 68 pass door. S.R. Stn. Selhurst
www.americanradiohistory.com
660 PRACTICAL WIRELESS December, 1965
WHAFtF.dE,p4
ONE TO BUILD YOURSELF FROM THE E RANGE
Build a loudspeaker system in a concrete pipe and obtain good results. Impossible? If it were,Wharfedale
would not recommend it. The fact is that experimental results of this type of enclosure were so successful
that Wharfedale have produced an inexpensive kit especially for the Do -it- Yourself enthusiast. The kits
come in two sizes -for 8" or 10" speakers and cost £5.0.0 and £6.5.0. In addition you will need a
spun concrete pipe which costs about 12/6 from good builders merchants. The concrete column can be
decorated with a variety of finishes- paint, wallpaper, fabric etc.
The top is fitted with a loose weave acoustic material.
RECOMMENDED UNITS FOR THE WHARFEALE CONCRETE COLUMN AID
SUPER 8 /RS /DD
A highly efficient full range speaker with the latest type of ceramic
ring magnet. Roll surround gives smooth low frequency response
down to 40 c /s. Power handling capacity 6 watts.
Impedance 15 ohms. 57.0.0 (Tax Paid)
SUPER 10 /RS /DD
A 10' speaker with double diaphragm, roll surround and powerful
magnet. This unit gives frequency response down to 30 c /s. Power
handlingcapacity 10 watts. Impedance 15 ohms. 511.13.4 (Tax Paid)
WHARFEDALE WIRELESS WORKS LTD. IDLE BRADFORD YORII/.
MFG Princ ole of construction of
system In concrete column
Anomie Cloth Cover
Diffusor
Batee
Foatn Houk Gasket
a' or 1t Speskkr (extra te kit)
BAP Wadding
Spun Contr./1114p.
Acoustic Filter
BAP Wadding
Positioning Blockt (3)
Foam Gasket
But with Tuning Vents WHARFEDALE TOWN
POST THIS COUPON TODAY;i
for idly illustrated simple to fallow construction folder
NAME.. Dept. P
ADDRESS
COUNTY.
www.americanradiohistory.com
PRACTICAL
WIRELESS DECEMBER 1965
VOL 41 NO 106
HAM OR SHAM ?
AN interesting question is posed by a reader in News & Comment this month. It has
been periodically raised before but there is no harm in examining the point again.
He asks, in effect -"What is an Amateur ?" An innocent enough question, you may
think, and one capable of simple reply, for surely it is only a matter of definition.
Briefly, our correspondent questions the right of an enthusiast to call himself an
"amateur" when his shack is full of professionally -built equipment. Is he, perhaps, to
borrow a term from another sphere, a "shamateur "?
It is undoubtedly true that the average amateur station today uses far more commer-
cially built gear than hitherto, and many stations hardly boast a single piece of home
constructed apparatus.
When commercially built transmitters were unavailable, everyone had to build
their own. When commercial communications receivers were beyond the pocket of
most amateurs, they made their own. When cheap and efficient test gear was hard
to come by, amateurs "rolled their own ".
Today, good receivers are within reach of virtually every amateur. Today, trans-
mitters of a wide variety are available to anyone able to buy them; auxiliary equipment,
for all needs, is plentiful. In fact, today the radio amateur can equip his entire station
and go on the air without even having to reach for his soldering iron -assuming he
knows what a soldering iron is for!
A common defence is lack of time to build up one's own equipment: Yet today most
people have far more leisure hours than they had in the days when at least some of the
station had to be home designed and constructed.
Ironically, these "shamateurs" would rear in alarm at the thought of a Citizens
Band for novices. Yet are they no better than mere operators themselves?
CONTENTS
News and Comment
A Transistorised L.C.R. Bridge
A Thumbnail History of Radio -Part
Guitar Magnetic Pick -up Unit
An Efficient Earth System
Miniature Oscilloscope -Part 2
On the Short Waves
Simple 2 -Band Phone Transmitter
Transistorised S.W. Converter
Circuit Disguises
Tape Recorder Conversion to Four Tracks
Tape Terminology -Part 5
Practically Wireless
A Low -power D.C. Inverter
Simple 3 -Valve Superhet
Club Spot -Plymouth R.C.
by Mike Fisher
3 by R. F. Farley, G3SSJ
by A. Clement
by Alan Ford
by H. T. Kitchen
page
662, 692
664
670
672
676
677
by John Guttridge and David Gibson, G3JDG 680
by F. G. Rayer, G3OGR
by J. G. Ransome
by, R. Leyland
by A. J. McEvoy, B.Sc.
by H. W. Hellyer
by Henry
by D. Bollen
by J. B. Willmott
684
688
690
694
698
705
706
713
721
All correspondence intended for the Editor should be addressed to: The Editor, "Practical Wireless ", George Newnes Ltd., Tower House,
Southampton Street, London, W.C.2. Phone: TEMple Bar 4363. Telegrams: Newnes Rand London. Subscription rates, including postage:
29s. per year to any part of the world. (e ) George Newnes Ltd., 1965. Copyright in all drawings, photographs and articles published in
"Practical Wireless" is specifically reserved throughout the countries signatory to the Berne Convention and the U.S.A. Reproduction
or imitations of any of these are therefore expressly forbidden. The JANUARY ISSUE WILL BE PUBLISHED ON
DECEMBER 9th
www.americanradiohistory.com
662
Competent Constructors
WHEN I first read R. A.
Packer's letter in the October
issue of PRACTICAL WIRELESS, I
felt rather annoyed. On reflec-
tion, I found it more amusing
than annoying for it expressed
most admirably, the carping
opinions and criticisms of people
who, lacking ability and initiative
try to degenerate the efforts of
more industrious souls.
The Editors of P.W., P.TV.,
P. Electronics and Radio Con-
structor have done me the
honour of accepting and publish-
ing my poor misguided efforts. I
cannot however recall any article
or articles credited to Mr Packer.
Perhaps he writes under a
pseudonym? If so, I would be
most interested to discover which
one. I would conclude by, very
humbly, offering Mr. Packer a
word of advice. If you must set
yourself up as a judge of other
people's work let us, by all
means, have a sample of your
work so that YOU in turn can be
judged.
H. T. Kitchen. Nuneaton,
Warwickshire.
Electronic Developments
NEWS ANC..
I MUST disagree with R. A.
Packer's remarks on the future
developments in electronics
(October issue). If he seriously
believes that the encapsulated
transistor will be obsolete by
1975. what does he think will
replace it? Sub -miniature etched
circuitry and slices of semi-
conductor are hardly practicable
for the amateur constructor.
In ten years, Mr Packer will
either have bought himself
a million -pound semiconductor
processing and etching plant, or .
given up, while the poor " incom-
petents" of today are still
enjoying themselves with their
" obsolete" valves and tran-
sistors.
Miniaturization is all right for
the equipment manufacturer
where it may reduce labour and
production costs, but why should
the amateur constructor follow
suit? Transistor equipment is
quite small enough for my needs.
I. M. Hutchings. Rugby,
Warwickshire.
ELECTRICALLY OPERATED TELESCOPIC MAST
A. N. Clark (Engineers)
Ltd., of Binstead. Isle of
Wight, have recently added
to their range of Telescopic
Masts a new series called
"Super E ". The unique fea-
ture of these latest designs
is that they are arranged to
be powered from a 12V
supply which most con-
veniently takes the form of
a vehicle battery. They are
thus eminently suitable for
mobile applications such as
radio telephones, etc. The
heights available range from
16 -40ft. From operating the
neat dashboard mounted
switch, the time taken for
the 25ft. mast to extend is
under 20 seconds. A similar
time suffices for retraction.
By means of a simple elec-
trical connection it is ar-
ranged that the mast cannot
remain extended if the igni-
tion switch is turned on.
*
CARRIER FREQUENCY IMPROVEMENT
In 1945 the BBC inaugurated high -precision frequency control
of its 200kc's transmission of the Light Programme from
Droitwich. The long -term frequency stability, which was then
within I part 10 , was considerably improved in January 1963 and
since then has been maintained within 5 parts in IO''.
A further improvement has now been made in the frequency
control of the Droitwich 200kc /s transmission resulting in a
long -term stability which is now within _I.5 parts in 10' ". Due to
the use of automatic frequency correction the excursion from
nominal does not usually exceed I part in 10".
With the recent increase in broadcasting hours of the Light
Programme, the Droitwich 200kc!s transmission is now avail-
able for 21 hours daily from 0400 to 0100 G.M.T
"WHICH ?" REPORTS ON RADIOS
The September issue of "Which ?" reports on 24 v.h.t. radios ranging in
price from L 1 to £42. The panel of experts tested the radios for sound
quality, freedom from interference, ability to receive weak signals
and ease of tuning.
The two most outstanding radios were among the most expensive:
"Which ?" names them, and the cheapest radio with the next best sound
quality, as Best Buys.
www.americanradiohistory.com
..COMMENT
NEW AVO VALVE DATA MANUAL
Avo (Ml Group) has just published the 17th edition of its Valve Data
Manual.
This reference book, an essential for the servicing engineer, gives
data on more than 8,000 valves in one volume otherwise available only
by holding individual literature from every valve manufacturer.
Among the sections of the book are details of commercial equivalents
of Service valves and Service equivalents of commercial valves; valve
equivalents; test data for receiving and small transmitting valves (giving
electrode connections and basing details); test data for tuning indicators,
high voltage rectifiers and Russian valves.
The Manual also gives special data on all valve testers made by Avo
since 1937.
The new Avo Valve Data Manual is available from the Spares Depart-
ment, Avo Limited, 92 -96 Vauxhall Bridge Road, London, S.W.I, and
costs CI I5s. (post free).
LONDON HI -FI SHOWROOM
Radio Rentals have opened a High -Fidelity showroom at 70 Baker
St., London, W.I. They have transformed the basement of their
West End branch into a complete demonstration studio where
visitors can, without obligation, browse to their heart's content,
hear their latest stereo records played on the latest equipment,
and receive the advice of a High -Fidelity specialist based
in the studio.
Although the showroom operates on a five- and -a -half day
opening, the public are invited to 'phone WELbeck 5387 for a
special appointment should the normal hours of business be
inconvenient for them.
Hi -Fi equipment is available from leading manufacturers
which include Goodmans, Garrard, Baird, Armstrong, Goldring,
Rogers and Leak.
POWER UNIT FOR "LEKTROKIT" RANGE
A.P.T. Electronic Industries Ltd.,
of Chertsey Road, Byfleet, Surrey,
announce an addition to the
"Lektrokit" Rack and Chassis
System of a new stabilised
power sub -unit.
The LKU -32I provides either
6V or 12V d.c. at load currents
up to 0SA and occupies chassis
space of one standard "Lektro-
kit" plate. The construction is in
the form of an open rectangular
tube so that the natural "chim-
ney effect" assists the cooling of
the heatsink. The shunt- stabil-
ised amplifier circuit is wired on
a printed card which comprises
one side of the chimney, and the
input and output connections
are brought out by means of
soldered pins.
The stability of the unit is better than 500:1 at 6V and better than 1,000:1
at 12V for +10% mains change. D.C. resistance: 0.0552 max., ripple is
10mV peak to peak, the size is 3 ;in. x 311- 5,-in. x 44.in. and the price is E12.
more News and Comment
663
Amateur Standards
BOTH R. W. Walker and
GW3SPA. in their replies to Mr.
Taylor's letter on the declining
c.w. standards of the British
amateur today, seem to have the
mistaken idea that, just because
an amateur has passed the G.P.O.
Morse test, everything in the
garden must be lovely and no
further improvement is necessary.
Yet, one only has to listen on
the bands to realise the truth of
GW3SPA's own comment " .
the standard of operating is
satisfactory as far as amateur
radio is concerned ". In truth, the
amateur world has a standard of
its own, and it is, generally speak-
ing, merely "satisfactory ".
There is obviously a vast
difference between fumbling
through the Morse test, as many
do, and producing good, reliable
Morse, sent at a reasonable
speed, over the air. And this is,
no doubt, the reason why so
many newly -licensed amateurs
choose the easy way out, avoid-
ing all further contact with c.w.,
adopting instead a 100% phone
policy.
What an improvement we
should find if the compulsory
use of c.w. only during the first
year were brought back. Under
these circumstances every
operator would be encouraged to
get his transmitter working
correctly on c.w. first, ensuring a
well -keyed T9 note, and some,
at least, of those who now
announce their dislike of c.w.
operating without having tried it,
would find they like it after all.
Bear up, then, Mr Taylor. Why
not get yourself a callsign and
come and join us on the c.w.
bands?
F. Allan Herridge, G3IDG.
Basingstoke,
Hampshire.
Correspondent Wanted
I WOULD like to correspond
with someone my own age (13)
who is interested in amateur short
wave radio.
B. Wright.
I Eastfield Road,
Barton -on- Humber,
Lincolnshire.
on page 692
www.americanradiohistory.com
664 PRACTICAL WIRELESS December, 1965
A Transistorised L.C.R. Bridge
By Mike Fisher Part One
SOME means of measuring the values of
resistors, capacitors and inductors is essential
in any good radio or electronics workshop.
however big or small, and this is equally true of
the workshop of the radio control enthusiast. In
the case of the latter, however, it is often essential
that such tests be carried out "in the field " well
away from the convenience of mains power
supplies. The measuring equipment must there -
fore be portable and self -powered if it is to be of
any real value to the operator.
The device that meets the above requirements
is the transistorised L.C.R. bridge and it is with
the design and construction of an instrument of
this type that this article is concerned.
It is considered by the writer that some readers
may decide to build a bridge with ranges other
than those used on the instrument that forms the
basis of this article and to this end it will be
essential to understand the basic design procedure
involved. It has therefore been decided to devote
a certain amount of space to this subject. Those
readers who have no interest in such details should
therefore turn directly to the full circuit diagram
and constructional notes.
Theory of the Wheatstone Bridge
The most basic form of measuring bridge is that
known as the Wheatstone and it is from this that
most other types of bridge are developed.
The circuit diagram of a simple Wheatstone
bridge is shown in Fig. 1 and, as can be seen,
consists of four resistance "arms" with a d.c.
power source connected to the junction of two
opposite pairs of arms and a detector, in this case
a moving -coil meter, connected across the
remaining pair of arm junctions.
The method of operation of the circuit is to
Fig. I:
Simple
Wheatstone
bridge circuit.
COVER
SUBJECT/
place an unknown resistor in the position of Rx
and to then adjust the variable resistor "RV until
a null reading is obtained on the detector. The
best way to understand the theory is to regard RI
and RV as forming a voltage divider chain with
the voltage connected between points A and B and
the tapping -off point at C, while R2 and Rx form
a second voltage divider chain connected to the
same supply as the first chain and with the
tapping -off point at D. The detector: connected
between points C and D, will indicate the
difference in voltage between the two tapping
points. When these two points are at the same
potential the detector will indicate zero` or a null.
These two points can only be at the same potential
when RV Rx or. to put it another way, when
R1.Rx= R2.RV. From this it can be seen that at
balance R2
Rx =RV.RI
From the above it can be seen that the actual
values of R1 and R2 have little importance in the
balance equation, it being their RATIOS that
really count. R1 and R2 are therefore known as
the "ratio arms" of the bridge and their ratios
are usually made some power of ten. If the scale
of RV is then calibrated in ohms it becomes a
simple matter to determine the value of Rx, the
unknown resistor, by merely reading off the value
of RV at balance and multiplying the reading by
the ratio of the ratio arms.
If, for example, the values of R2 and R1 were
10011 and 1052 respectively the ratio would be
10:1 and the multiplying factor 10. so that if it
was found that at balance RV gave a reading of
52652 it could be seen that the value of Rx was
5,26052.
In practice it would be found that if RV was
made a lkfl potentiometer the lower =end of the
scale reading would be very cramped. and the
upper readings in the above case would be limited
to 1Okft. It is therefore general 'practice to
provide the bridge with several switched ranges.
This is done by switching the ratios of the ratio
arms, always by powers of ten, and it is then found
that a single calibrated scale on RV will suffice
for all ranges.
Fig. 2 shows the circuit diagram. with switching
details, of the complete Wheatstone bridge
arrangement that is used on the instrument that is
used as the basis for this article. As' can be seen.
a total of seven ranges is available, giving
www.americanradiohistory.com
December, 1965
readings from 0 to
10MÍ2. To prevent exces-
sive current flowing on
the lower ranges, resul-
ting in overloading of
the supply, a limiting
resistor is connected in
series with the supply
and also acts as a semi-
automatic sensitivity con-
trol by voltage divider
action.
It may be noted that
several bridge circuits
that have been published
in the past have made
use of a.c. as the power
source for the Wheat-
stone bridge circuit, thus
enabling headphones to
be used as the detector
in common with the capacitance and inductance
measuring bridge circuits. The disadvantage of this
system is that if the resistance to be measured con-
tains any reactive components inaccurate readings
will be obtained. It would be almost impossible,
for example, to measure the d.c. resistance of a
PRACTICAL WIRELESS 665
To detector
Seven range Wheatstone circuit used on prototype
instrument.
Fig. 3:
Simple De Sauty
bridge circuit.
tuning coil or choke with such a circuit. D.C. has
therefore been used to energise. the Wheatstone
bridge in the instrument described in this article.
Several bridge circuits exist which may be used
for the measurement of capacitance but that
known as the De Sauty
is generally the most
favoured.
The circuit diagram of
a simple De Sauty bridge
is shown in Fig. 3 and,
as can be seen, the basic cx
configuration is similar
to that of the Wheat-
stone circuit. Each of the
lower bridge arms is re-
placed by a capacitor
and series resistor, how-
ever, and the bridge is
energised from an a.c.
source.
In the De Sauty or
any other bridge that
measures capacitance it
is necessary to balance
To detector
9kC1
Bridge Switch
Range Position \
0-10rc
0 -I00Í2 2
0-1kÍì 3
0 -10kí2 4
0- I00ki2 5
0-1 Meg 6
0 -10Meg 7
impedances against one another. In this particular
case, regarding the chain Rl and Zs and the chain
R2 and Zx as voltage dividers again, it can bet
Rl R2
seen that at balance = . Lt must be
Zs Zx
realised, however, that an impedance contains both
resistive and reactive components, so that in order
to obtain a true balance of the bridge it is
necessary to balance for both phase angle and
magnitude.
In the circuit diagram Cs is a standard
capacitance and Rs its loss angle reference. Cx
and Rx represent the series combination of
impedance of the unknown capacitor, Rx not, of
course, being a separate physical entity by an
inseparable part of the capacitor.
The frequency of the energising source is
common to both reactive parts of the circuit and
it can therefore be shown that the frequency of
operation plays no part in the actual balance
equation. In practice the bridge is balanced by
means of both the variable resistor Rs and the
main balance control Rl, a null being obtained in
each case.
At balance it is then possible to read off both
To detector
Fig. 4 Seven range De Sauty circuit used on prototype.
Bridge Switch
Range Position
0-100µF `-a )
0-IOµF Z
0-IµF 3
0-0IµF 4
0-0.011,F S
0-I000pF 6
0-100pF ; :7
www.americanradiohistory.com
PRACTICAL WIRELESS December, 1965
diagram of a typical example is shown in Fig. 5
and once again it can be seen that the same basic
configuration as that of the Wheatstone bridge is
used consisting of four " arms".
rR2 In the Hays bridge a standard capacitor is
connected in the opposite arm to the unknown
inductance. Again the bridge works on the
principle of balancing impedances. As most
readers will realise, a capacitor introduces a phase
shift in the opposite direction to that of an
inductance; by placing the inductance and the
capacitance standard in opposite arms it is possible
to cancel the phase shift of the circuit.
It should be noted that the Zx arm has been
shown as consisting of the unknown inductance
with its unknown equivalent parallel resistance,
Rx, and that this is balanced by using an
equivalent series resistance Rs with the standard
capacitor Cs.
As the resistive as well as the reactive com-
ponents of the unknown inductance must be
balanced in order to obtain a true reading it is
necessary to use both Rs and RI in order to
obtain a final balance.
It can be shown that at balance
Lx= R I.R2.Cs
Rx =R1. Rs.
If the frequency of the energising source is
accurately known the loss angle of the inductor
can be worked out from:
Detector
Zx
Fig. 5: Simple Hays bridge.
the capacitance and the series resistance of the
unknown capacitor.
At balance it can be shown that
Cs
Cx =R1. R2
and Rx =Rs. R1.
The loss angle of the capacitor under test can
also be worked out from the formula:
tan S= Rs.Cs.6.28f., but as it is necessary to
know the precise frequency of operation this
formula can be disregarded for the instrument
under consideration.
From the formula for Cx it can be seen that
the ratio arms of this bridge comprise R2 and the
standard capacitor Cs. If the ratios of these two
are arranged to powers of ten the same calibration
points as used for the balance control (Rv) may be
used for both bridge types.
The circuit of the complete De Sauty bridge, as
used in the instrument under consideration, is
shown in Fig. 4. It can be seen that seven ranges
are available, giving readings from 0 to 1000.
The most favoured bridge for the measurement
of inductance is the Hays Bridge. The circuit
To detector n
Lx
To detector
Flt. 6: Seven range Hays circuit used on prototype.
KR
and
1
tan S- 6.28.Rs.Cs.
It may be noted that the Q of an inductance
1 but it should also be noted that the
tan S
figure obtained only applies to the Q at the
particular frequency of test.
From the formula for Rx it can be seen that
in the case of the .Hays bridge it is R2 and Cs
that form the ratio arms. The same calibration
of R1 as was used for the two earlier bridges. is
again used and when balance of the bridge has
been obtained the value of the unknown
inductance is found by reading the value of R1
and multiplying by the
value given by the ratio
arms. The seven -range cir-
cuit used in the instru-
ment that forms the basis
of this article is shown
in Fig. 6.
100µH I The circuit wiring and
I mH 2 components of a practi-
IOmH 3 cal bridge or any other
I00mH 4 piece of electronic equip -
I H 5 ment must inevitably
10H 6 contain stray induc-
1001-1 7 tances and capacitances.
If 100% accuracy of
readings on all ranges is
to be obtained these
strays= must be either
Bridge
Range Switch
Position
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
balanced or accounted for. In very high quality
commercial bridges a system known as the
Wagner Earth is used to this end and involves.
amongst other things, the balancing to earth of
both the detector and supply source and the
extensive screening of all components, wiring, etc.,
and the balancing of any strays that still remain.
This is a most complex and expensive process and
beyond the scope of this article. Errors of reading
will only occur to any noticeable degree, however,
on the most extreme ranges of an instrument that
is not so treated. If the bridge described in this
article, for example, is quite literally lashed
together to conform to the circuit diagram and
the scale of R1 is calibrated directly by its
resistance it will be found that, providing
standards of 0.3% or better are used, readings
accurate to 1% will be obtained on all ranges
above 1,000pF. Below this errors will begin to
creep in and it will probably be found that it is
impossible to get a balance at all using a Cx of
15pF. It is most unlikely, however, that readings
to this low level will be required.
Accuracy of Readings
Regarding the accuracy of readings that can be
obtained it may be noted that the worst error of
reading that can be obtained (ignoring the error
due to strays mentioned above) is three times
greater than the accuracy of the standards used.
Thus, if 1% standards are used throughout, errors
as great as 3% may be found in the final reading.
It is therefore recommended that standards of
better than 0-3% be used throughout if an overall
accuracy of better than 1% is required.
It is also found that high- quality commercial
bridges use accurate frequency oscillators to
provide the energising source on the a.c. ranges in
conjunction with tuned detector amplifiers. This
is done for reasons already mentioned, i.e. so that
accurate measurement of power
factor, Q, etc., can be obtained.
It is felt by the writer that, as in
the case of the Wagner Earth.
refinements of this kind are of
little interest or use to the
average constructor and they
have therefore not been included
in the bridge under considera-
tion. As has already been pointed
out, frequency of operation will
have little or no effect on the
accurate reading of values of
capacitance or inductance in the
circuit used.
In order to keep costs of the
prototype instrument to a mini-
mum, components that were
readily at hand were used; no
particular efforts were made to
miniaturise by purchasing special
components, In point of fact the
two transformers used in the
transistorised circuitry were
taken from an .old valve equip-
ment.
667
Fig. 7: Ikc /s oscillator.
The a.c. energising source consists of a simple
single transistor transformer feedback oscillator
the circuit of which is shown in Fig. 7. The only
transformer available when the prototype circuit
was built was a 3:1 interstage audio valve type
and the circuit was built around this. Many other
transformers are suitable for use in the basic
circuit shown, however, but as their use will
involve changes in other circuit components,
further discussion of the circuit will be left until
the "Constructional Notes" section of this article
is reached.
For energisation of the Wheatstone bridge
circuit 9V d.c. fed to the bridge via a 9kfl limiting
resistor is used.
The Detector Circuit
As has already been mentioned, the bridge
described in this article differs from most other
amateur built types in the fact that d.c. is used to
energise the resistance measuring circuit, thus
making possible certain kinds of test which could
fig. 8 A.C. D.C. detector circuit.
www.americanradiohistory.com
668 PRACTICAL
not otherwise be carried out. The -major disad-
vantage of this system is that the detector circuit
must of necessity be far more complex than in
other types of bridge. Phones with their high
sensitivity can clearly not be used as an indicator
on d.c. unless a chopper -type circuit is included in
the instrument and that would involve consider-
able complication. The solution to the problem
is to use a visual balance indicator and it was
decided that the only suitable device at the low
voltages involved was a moving -coil meter, and as
a centre zero type was not available at the time
when the circuit was built the circuit had to be
built around a conventional " end -of -scale " zero
kind.
Circuit Requirements
The problems or requirements of the circuit
were as follows: The indicator had to respond
equally well to a.c. and d.c. signals. The meter
had to give a reading that was very sensitive to
magnitude of signal but independent of polarity
of signal, i.e, it had to give a very sensitive " null"
reading. Finally the meter or indicator had to
give a very positive indication of the balance
point, showing a needle, deflection of, say, 1 /10
of scale for a current change of 2µA at the balance
point, but had to withstand out -of- balance
currents of over 1mA without smashing the pointer
against the stop or causing any damage to the
circuitry. A non -linear response was called for.
The above problems were finally solved by
using the circuit shown in Fig. 8. This consists
basically of a d.c.- coupled amplifier feeding a
long -tailed pair, each transistor in this pair having
its own emitter load as well as the common one.
Between the emitters of these two transistors is
connected a bridge rectifier feeding a 50µA meter.
If the two transistors are perfectly balanced their
emitters will both be at the same potential and no
current will flow through the meter. Should any
unbalance occur a difference voltage will be
generated between the emitters and a current will
flow through the meter, the rectifier ensuring that
the direction of meter current flow is independent
of polarity or out of balance.
Non -Linearity
Non- linearity of response is obtained by wiring
a resistor in series with the meter and connecting
a germanium diode in parallel with the combina-
tion as shown. The diode is a non -linear device
the forward resistance of which varies with
applied voltage. When only a few millivolts are
applied, as in the case when the meter shown is
passing only a couple of microamps, the resistance
of the diode is quite high, in the order of tens of
kilohms; little shunting effect due to the diode
therefore takes place. As the applied voltage is
increased, however, the diode resistance falls and
begins to act as a shunt, and when a couple of
hundred millivolts are applied the diode resistance
falls to such a low value that it forms a virtual
short across the meter circuit. Non -linearity is
thus obtained.
Balance of the circuit with zero voltage input is
WIRELESS December, 1965
obtained by adjusting the collector loads of the
two input transistors with the 10kí1 preset pot.
On a.c. the balance point of the circuit will have
little or no effect on the accuracy of readings but
in the case of the resistance range, where d.c. is
used, this is not so and considerable error may be
introduced if the detector balance control is not
correctly set. Unfortunately it is not possible to
apply base bias to the first two transistors in this
circuit and a certain amount of drift from balance
point takes place. It is therefore necessary to
carry out fairly frequent checks of balance and to
this end a shorting switch is wired across the input
terminals of the circuit; the method of setting up
is to close the shorting switch, which is of the
self- return type, and then set the balance with the
10kí2 pot.
The Input to the circuit is applied between the
two base connections of the input transistors,
directly in the case of d.c., via a transformer in
the case of a.c., it having been found that d.c.
components existed in the a.c. bridge circuits
during measurement, which caused misleading
indications.
It is important to note that the generator circuit
and the detector circuit both use separate 9V
batteries.
The current consumption of the detector varies
between 3 and 4mA and the consumption of the
a.c. generator is a mere 1.5mA. The maximum
current consumption from the d.c. supply on the
resistance ranges is ImA, so that the maximum
total consumption of the complete instrument is
6.5mA.
(TO BE CONTINUED)
IF
YOU
NEED
Fire Alarm System
Multi -range Test Meter
or
the very latest
S.C.R. LIGHT DIMMER
G ET
PRACTICAL ELECTRONICS
DECEMBER ISSUE
ON SALE NOVEMBER II
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 669
i NEXT MONTH in PRACTICAL WIRELESS i
16 -PAGE
Pull -out Booklet
SHORT -WAVE DATA
Another vital Booklet packed with at -a-
glance information on When and Where to
Listen - Amateur and Broadcasting Bands
- Codes and Abbreviations - International
Prefixes - Frequency and Time Signal
Transmissions - How to Become a Radio
Amateur.
Other outstanding features
in this issue
PUSH -PULL ELL80 AMPLIFIER
INEXPENSIVE MULTIMETER
AERIAL TUNERS
UNDERSTANDING FM
MAKE
SURE OF
YOUR
COPY!
Hand this
Form to Your
Newsagent
JANUARY
ISSUE
ON SALE
DECEMBER
9th
To (Name of Newsagent)
Please reserve /deliver the January Issue of Practical Wireless (2 -), on sale
December 9th, and continue until further notice.
NAME
ADDRESS
4
www.americanradiohistory.com
670 PRACTICAL WIRELESS December, 1965
by R. F. Farley, G3SSJ
A Thumbnail History of Radio
PART 3: WIRELES1 FOR ENTERTAINMENT
IT is interesting to note that only a few weeks
before his death in 1956 Edwin Armstrong said
that nobody had understood the valve until six
years after its introduction in 1907. Be that as it
may, except for use as a telephone amplifier the
valve had little use prior to 1914, however, about
this time it was realised that a single triode would
function as a heterodyne oscillator, detector and
amplifier.
The Great War demanded' continual improve-
ment in communications with the result that both
production and development expanded rapidly. By
the end of the war receivers were produced using
as many as six stages of high frequency amplifica-
tion followed by a detector and several low -
frequency stages. Captain H. J. Round was one of
the foremost British pioneers in this field and gave
his name to one of the early triodes.
Early Valves
The two most common types of valve were the
"'R" type valve and the " V24", although the
latter did not make its appearance until towards
the end of the war. The V24 was considered
especially suitable as a high frequency amplifier
but its characteristics would doubtless raise a smile
today. It operated with an anode voltage of from
25 to 30V and the filament cyirrent was P75A at
SV. It had an approximate voltage magnification
of 6. The famous R valve required a .fllam$rt
current of 0.67A at 6V, with up to 70N4 on the
anode depending on the state of the vacuum. Both
types were to survive well into the 1920's. Gain
from the R type valve seems to have been largely
a matter of luck. When at the end of the war these
valves became available to amateurs on the surplus
market, an especially soft valve was often sought
after. Great magnification of c.w. signals was
Fig. is Circuits of early crystal receivers.
possible due to the ionisation effects although grid
current was considerable.
On the field of battle the problem of transport-
ing heavy batteries was considerable. This led to a
number of experiments to lower the impedance of
the valve by adding a fourth electrode. Captain
Scott Taggart patented such a device which could
be operated by a single low tension battery.
Interest in " high tensionless" circuits was revived
towards the mid- 1920's, but little development on
the low impedance valve took place until after the
Second World War.
In America amateur radio equipment was being
sold extensively. Crystal sets with large loose
coupled tuners and even spark transmitters could
be had off the shelf. It was during 1916 that broad-
casting was started experimentally by the Westing-
house company. Edwin Armstrong served as a
captain with the American Army in France for
two years. In those days aircraft were located
by purely acoustical means, and this was far from
effective. Armstrong designed a receiver for loca-
ting aircraft by picking up the radiation from the
ignition system.
By the end of the war spark transmitters were
fast becoming obsolescent although some survived
into the 1930's.
Alexanderson's Alternator
It was the Alexanderson alternator that provided
the high powers for trans -Atlantic round -the -clock
working on low frequencies, though some arc
stations were also in use.
Alexanderson was born in Sweden in 1$78 but
after graduating in Stockholm he settled in
America, where he later became chief engineer of
R.C.A., but it was whilst working for the General
Electric company that he developed the first
successful high -frequency alternator for Professor
Fessenden. It was a very costly piece of develop-
ment engineering because of its mechanical
problems, for its armature had to rotate at high
speeds and its mass was great. This meant that
bearing wear would be very high unless the
bearings were machined to fantastic degrees of
accuracy. There was also the problem of centri-
fugal force. Since frequencies of many kilocycles
were required the armature had to be driven
through a step -up gear -box; there were then no
motors to operate directly at these speeds. There
is an excellent example of Alexanderson's alter-
nator in the Science Museum, together with a
wonderful collection of historic wireless instru-
-ments.
In America the first regular broadcasting station,
KDKA, succeeded the experimental station of the
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
Westinghouse company. This triggered off an
American broadcasting boom and gave further
impetus to British enterprise.
The Marconi company set up a 6kW transmitter
at Chelmsford and it was here that Lord North-
cliffe financed the famous Melba broadcasts for
the "Daily Mail ". Dame Nellie Melba was at
that time the leading international opera star and
her historical broadcast was made on June 15th,
1920, before a distinguished audience of V.I.P.s
The broadcast was successfully received through-
out Europe and aroused great public enthusiasm.
Melba sang into an ordinary telephone carbon
hand microphone, but at that time so wondrous
was the achievement that the distortion passed
unnoticed.
Also at this time a regular series of concerts was
being broadcast from The Hague and these figure
prominently in the advertising material of manu-
facturers. A two -valve receiver could be bought
for about £30 but most listeners built their own.
Even so, the cost was high and licensing conditions
were carefully bound in red tape, the Defence of
the Realm Act having only recently been relaxed.
References were required before licences could be
granted to "approved persons " for experimental
purposes only, although the Wireless Society of
London fought hard for better facilities. The
Wireless Society of London later became the
R.S.G.B. Amateur transmitting licences were also
issued for powers generally not exceeding 10W.
Some amateurs found it necessary to broadcast
frequent programmes of gramophone records.
Particularly well known at the time was Station
ZAZ at Guildford, owned and operated by
Mr. William Le Queux, the novelist. Less
fortunate amateurs contributed their skill to ZAZ,
which provided them with an outlet they could
not afford themselves.
After a short time the broadcasts from Chelms-
ford were banned by the G.P.O. because they were
interfering with cross -Channel air communication,
but after further negotiations the Marconi corn-
--Y
l
+
lOQ9o0, .9000
Fig. 2: The Armstrong "Super Regen". Used by the more
adventurous to receive weak amateur transmissions
below 200m.
671
Fig. 3: The Reinartz circuit.
pany started a regular series of broadcasts in
February, 1922, which are unique in broadcasting
history. From a hut at Writtle the brilliant Peter
Eckersley, supported by a wonderful young team,
showed what the microphone could do. The power
at Writtle was only 200W and even this was
almost strangled by legislation. -
Following each three minutes of broadcasting a
period of three minutes' silence was demanded, so
the obvious choice of material was gramophone
records. But enterprise thrives in the face of
adversity and one evening Eckersley began impro-
vising in fropt of the microphone. He was
immensely witty and his inventiveness enabled him
to use the absurd restrictions to advantage. Before
long the whole staff at Writtle were contributing
programme material of a largely impromptu
nature. At the end of every broadcast Eckersley
improvised a little rhyme, inviting listeners to
report on reception and give details of the
" hook -up " they were using. Sadly no recordings
exist of these pioneer broadcasts but 2 Emma Toc
is still very much alive in the memories of old -
timers. Ordinary phone hand microphones were
still in use at 2MT and its aerial was a 140ft, four -
wire inverted "L " supported by masts 110ft high.
During the same year broadcasting began from
2L0 at Marconi House in the Strand with a power
of only 100W. Broadcasting was also being
carried out on an experimental basis in the pro-
vinces by several of the larger electrical firms. In
the meantime the American scene had become one
of chaos. Hundreds of stations were coming on
to the air but it was a great achievement to receive
less than three at a time! Even Radio Caroline';
most ardent supporters would wince at
BBC Formed
Fortunately in England the British Broadcasting
Company was formed before things got out of
hand. Its prime object was public service. Its
first Director of Programmes was Arthur Burrows,
a man of serious temperament, which distinguished
-continued on page 675
www.americanradiohistory.com
672 PRACTICAL WIRELESS December, 1965
A Guitar
Magne tic
Pick -up
Unit
FIRSTLY it is essential that the instrument to
be electrified has steel strings in order to
produce a signal in the pick -up coil when a
string is plucked. Nylon or gut strings therefore
must be discarded in favour of steel and when
considering the coiled string numbers 3 to 6 tape -
wound type are recommended.
Magnets
These magnets, obtainable from any good iron-
mongers, are known as Eclipse " button type " the
size used is in fact the smallest in the particular
range. See Fig. 1.
Fig. I: Details of the
Eclipse "button- type"
magnets as used in the
pick -up.
Base
Perspex or similar plastic }in. thick is used for
the base and the holes for mounting the magnets
are drilled as shown in Fig. 2 and countersunk on
the reverse side to accommodate the 4BA brass
countersunk screws. The brass retaining nuts
must be filed until the nut will drop into place
between the magnet pole pieces. This method of
fastening ensures that the nuts are held locked in
place. A suitable adhesive could also be used for
mounting the magnets, although this means has not
been tried.
2%.
11/2; dia. holes terminals
- _Or
1/8'
i- .-`l
1/8' thick board
f g. 2: Drilling details of the }in. thick plastic used for
the base.
BY
A. CLEMENT
Coil Formers
Cut a strip' of gummed paper }in. wide and wrap
around one of the magnets, moistening the paper
after the first complete turn; a 6in. or Tin. length
should be long enough to make the tube rigid.
The top and bottom of each former can be cut
from a variety of materials -card, plastic or
celluloid, etc.- although the prototype used
celluloid and this was very satisfactory. After the
centre hole of these pieces has been made to fit
the tube cut or file a small " v " notch as shown
in Fig. 3 and drill a small hole adjacent to this.
Assemble the formers, using glue such as clear
" Bostick" or model aero cement.
Oa. .V'shaped Small
hole notch hole
Fig. 3: Coil formers showing "v" notch and adjacent hole.
Coil Windings
The coils are wound from enamelled copper
wire. The gauge is not critical and whilst 3$s.w.g.
was used originally this was only because it was
available from the junk box. Anything thicker
would not give sufficient turns on the formers,
although up to 46s.w.g. or so could be used equally
well. A small piece of this flexible wire is soldered to
the start of each winding and lead through the
" v " notch. The enamelled wire is then wound
on until the formers are completely " full " and
the end is taken out through the small hole.
With the magnets in the correct position on the
base the pole pieces should be in line one with
each string, and in order to achieve this it may be
necessary to alter the spacings of the strings where
they pass over the bridge.* The coils Can now be
placed in position and wired in series. Two small
brass terminals cemented to the base are used to
anchor the two free ends of the windings acid the
lead to the amplifier is taken from these two points
through the hole in the cover.
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 673
LAFAYETTE HA 63
COMMUNICATION
RECEIVER
7 valves + Rectifier. 4 Bands
550 Ke /s -31 Mc /s. 'S' Meter -
BFO -ANL- Bandspread Tuning.
200/250v. A.C. Brand New.
24 Gns. carr. paid.
STAR SR 40
COMMUNICATION
RECEIVER
4 Bands 550 Kc /s-30 Mc /s. 'S'
Meter - BFO - ANL - Bandspread
Tuning -Built in speaker. 200/
250v. A.C. Brand New.
18} Gus. Carriage 10 / ,
OS /8B /U OSCILLOSCOPES
High quality Portable American Oscilloscope.
3in. c.r.t. T/B 3c /s-50 kc /s X Amp: 0 -500 kc /s
Y Amp: 0 -2 Mc /s. Power requirements 105 -125v.
A.C. Supplied in "as new" condition, fully
tested.
£25. Carr. 10 / -. Suitable 230/115v. Trans-
former. 15/8.
NEW MODEL!
LAFAYETTE HA -230 AMA-
TEUR COMMUNICA-
TIONS RECEIVER
Supersedes model HE -30. 8 valves
+ rectifier. Continuous coverage
on 4 bands. 550 Kc /s-30 Mots. In-
corpDora 2 IF stages, Q
Multiplier, tes 1 BFO,
RF and ANL, 'S' meter,
electrical read, Aerial trim-
mer, etc. Supplied brand new and guaran-
teed.
Also available in Semi -K m 25 Gn98AE for full details.
50µA .. 32/8
1000.A .. 29/8
200µA .. 27/6
500µA .. 25/-
50 -050µA.. 29/6
100 -0 -100µA 27/6
S0 ÁaPA 22/6 2A. DC.. .. 22/8 500V. AC
POST EXTRA. Larger sizes available -send Meter r lists.
ILLUMINATED "S" METER 1 "/ ,m. square front. Cal. in S units.
6V. lamp. 29/6. P.P. 1/ -. Ditto Vhein. square. 39/8. P.P. 1 / -.
AVOMETERS TRANSISTORISED
TWO -WAY
CLEAR PLASTIC PANEL METERS
First grade quality. Moving Coil panel meters
available ex- stock. S.A.E. for illustrated
leaflet. Discounts for quantity. Available as
follows. Type MR38P 1 21/32in. square fronts,
2mA .. .. 22/6 3V. . . . .2 2 / 8 /8
22/6 10V. DC 22/6
IOmA
.. .. 22/6 20V. DC 22/8
ÓmA .. .. 22/6 1ÓÓV DC 22/6
100mA .. . 22/8 150V. DC . 22/8
150mA .. .. 22/6 300V. DC 22/8
200mA . .. 22/6 500V. DC . 22/8
.300mA .. .. 22/8 750V. DC . 22/6
500mA . . 22/6 15V. AC 22/6
750mA .. .. 22/8 50V. AC 22/6
1 -0-1mA .. 22/6 150V. AC 22/6
1A. DC . . 22/6 300V. AC .. 22/6
22/8
29/8
TELEPHONE
INTERCOM
Operative over amaz-
ingly long distances.
Separate call and press
to talk buttons. 2 -wire
connection. 1000's of
applications. Beauti-
fully finished in ebony.
Supplied completewlth
batts. & wall brackets.
7 gus pair. P. & P. 5/ -,
Supplied
recondi-
tioned,
guaran-
teed per-
fect.
Model D,
£8.19.8.
Post & Ins
5/ -.
ERSKINE TYPE 13
DOUBLE BEAM
OSCILLOSCOPES
Timebase 2 e /s:
750 kc /s. Separate
Y1 and Y2 ampli-
fiers. Up to 5.5
Mc /s. calib at 100
kc /s. and 1 Me /s.
110/230 v. A.C.
Guaranteed per-
fect. 127.10.0.
Carr. 20/ -,
MINE DETECTOR No. 4A
Fully portable. Completmetals.
e
instructions. 39/6 each. Carr.
10/ -. Battery 8/8 extra.
MAGNAVOX 363
TAPE DECKS
New 3 speed tape deck. super-
sedes old Collaro studio deck.
2 track, 210.10.0.
4 track, £13.10.0. Carr. Paid.
SILICON RECTIFIERS
200 P.I.V. .. .. 200mA 2/8
1.000 P.I.V. .. . 650mA 7/6
800 P.I.V. .. .. 500mA 5/6
400 P.I.V. .. .. 3 amp 7/6
400 P.I.V. .. ... . 165mA 1/8
70 P.I.V. .. .. 1 amp 3/6
95 P.L V. .. 3 amp 5/6
Post extra.
AMERICAN TAPE
First grade quality American
tapes. Brand new and guaranteed.
Discounts for quantities.
3in. 225ft. L.P. - 4/-
3fin. 600ft. T.P. mylar 10 /-
51n. 600ft. std. plastic 8/8
5in. 900ft. L.P. acetate 10 /-
51n. 1200ft. D.P. mylar 15/-
5in. 1800ft. T.P. mylar 35/-
Olin. 1200ft. L.P. acetate 12/6
511n. 1800ft. D.P. mylar 22/6
51in. 2400ft. T.P. mylar 45/-
7M. 1200ft. std. mylar 12/8
710. 1800ft. L.P. acetate 15/-
7in. 1800ft. L.P. mylar 20/-
7in 2400ft D.P. mylar
NEW MODEL!
LAFAYETTE HA -SS Aircraft
Receiver
108 -136 Mc /s. High selectivity and
sensitivity. Incorporates 2 RF
stages including 6CW4 Nuvistor, 8
tubes for 11 tube performance,
solid state power supply, adjust-
able squelch control, slide rule
dial, built In 4in. speaker and front
panel phone jack. 220/240v. A.C.
Supplied brand new and guaran-
teed. 19 Gns. Carr. 10 / -.
TE -22 SINE SQUARE WAVE
AUDIO GENERATORS
Square: 20pc.ps to Kc/s on 4Ou put
imp. 5000
ohms. 200/
240 v. A.C.
-' ,, --._.- ' `= Brand new
Guaran-
teed. £15.
Carr. 7/8.
LEADER LSG -I0
R.F.SIGNAL GENERATOR
120 Ke /s-260 Me /s on 6 ranges.
Variable R.F. and A.F. outputs.
Large clear scale. Size 7} x 105 x
4}in, 200/250v. A.C. operation.
Brand New. £12. Care. 7/6.
TWO -WAY RADIOS I
Superb quality. Com-
plete with all acces-
sories and fully g't'd.
3 Transistor 27.19.8 pr.
4Transistorllgnspr.
9Transistorl9gnspr.
10 Transistor
Post extra. (S.A.E.
S pr. . for full
details).
VOLTAGE STABILIZER
TRANSFORMERS
Will stabilize
your mains
voltage. Ideal
for TV receiv-
ers and Indus-
trial equip-
ment. Input
80 -120 V. and
160 -240 v. Con-
stant output
110 v. or 240 v.
250 watts.
Brand newguaranteed.£10.10.0
Carr. 7/6.
VARIABLE VOLTAGE
TRANSFORMERS
Brand New Guaranteed. Fully
Shrouded. Input 230v. 50/60 c /s.
Output 0 -260 v.
1 Amp 24.10.0
2.5 Amp 25.17.6
5 Amp £9 0.0
8 Amp 213.10.0 '
10 Amp 217.10.0
12 Amp 219.15.0
20 Amp 232.10 .0
LAFAYETTE
NUVISTOR
GRID
DIP METER
Compact true one
hand operation.
Frequency range
1.7- 180Mc /s. 23Ov.
AC operation.
Supplledcomplete
with all coils and
Instructions. 612,10.0. carr. 5 / -.
/r9
n. 3600ft. T.P. mÿler /- 2.5 Amp Portable
ostalte 2/- Over 23 £3 post paid. Meter, Fuses, with 29.17.6.
,.
MODEL TE -12
6/30//120/600/1 /
3,000/6,000 v. D.C.
0/6/30/120/600 /1,200
v. A.C. 0 /60µA /6/
60 /600 mA. 0 /6K/
600K / 6 Meg. / 60
Meg. O. P.F. -.2
MFD. 25.19.11. P.
& P. 2/6.
MODEL 500
30,000 0.p.s,. 0/.5/
1/2.5/10/25/50/100 /
250 / DC 500 5/10/25/
100/250/500/1.000
v. AC 0 /50µq/5/
DC, 0 /880K /66
Meg /60 Meg n
28.17.6. Post
Paid. S.A.E. for
full details.
TE-5I NEW
20,0000 /VOLT
MULTI -
METER
0/6/60/120/1.200
V. A.C. 0/3/30/60/
300/600/3,000 v.
DC. 0 /60µA /12/
300 mA DC. 0/
60K/6 Meg. ohm.
24.5.0. Post &
pack. 2/6.
OPEN 9 a.m, to 6 p.m. EVERY
DAY MONDAY- SATURDAY
Trade Supplied.
Q; (RADIO) LIMITED
Phone: GERRARD 8204/9155
Cables: SMITHEX LESQUARE
LISLE STREET, LONDON, W.C.2
www.americanradiohistory.com
674 PRACTICAL WIRELESS December, 1965
Make Yoeiri4b///tq
PAY
UNLIMITED OPPORTUNITIES exist today for "getting
on" . but only for the fully trained man. Let ICS's tuition
develop your talents and help you to success.
STUDY IS EASY with ICS guidance. The courses are
thorough. Printed manuals, fully illustrated, make study simple
and progress sure.
YOUR ROAD TO SUCCESS can start from here -today.
Complete this coupon and post it to us, for full particulars of the
course which interests you. MODERATE FEES INCLUDE ALL
BOOKS.
Take the right course now .
HORTICULTURE
Home Gardening
Park Gardening
Market Gardening
MANAGEMENT
Business Management
Hotel Management
Industrial Management
Office Management
Personnel Management
Public Relations (1Pß)
Transport Management
Works Management
Work Study
Foremanship
MECHANICAL & MOTOR NNG'NO
Engineering Matbs.
Diesel Engines, Welding
Industrial Instrumentation
Workshop Practice
R etrigeratlon
Motor Mechanics, eta
POLICE
Entrance Examination
Police Promotion (Edae. Subi.)
PHOTOGRAPHY
Practical PholograPill CT R1CAL
RADIO, TV & ELE
Servicing a Engineering
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SELLING
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ou a Water Colour
BUILDING t CIVIL ENG'NG
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Architectural, Mecludoa!,
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Pig a Poultry Keeping
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GENERAL EDUCATION
O.C.E. subjects at Ordinary I
Advanoed Level
Good English
Foreign language.
INTENSIVE COACHING for all principal examinations
-- G.C.E., Secretaryship, Accountancy, Engineering,
Work Study, Management, Radio, Architecture and
Surveying. Special course for G.C.E. French Oral Test.
Member of the Association of British Correspondence Colleges
11 -- I
INTERNATIONAL C UR RESPONDENCE SCHOOLS
2)
Intertext House, Parkgate Rd., London, S.W.I I I
Send FREE book on
Name
Address
Occupation 12.65 I
INTERNATIONAL CORRESPONDENCE SCHOOLS
TRANSISTOR ELECTROLYTICS
32µF
25µF
2µF
3uF
8µF
10uF
12µF
20uF
30µF
40µF
25uF
2µF
32µF
4µF
8µF
IÒµF
COMPARE THESE PRICES!
I.5 volt 25µF 6 volt 4µF S volt
3 volt 30µF 6 volt 5µF 5 volt
3 volt 50µF volt 6µf 5 volt
3 volt 100µF 6 volt 8µF 5 volt
3 volt 2µF 9 volt 16µF 5 volt
3 volt IOpE 9 volt 32µF 5 volt
3 volt 20µF 9 volt 50µF 5 volt
3 volt 2µF 2 volt 64µF 5 volt
3 volt 3µF 2 volt 2.5µF 25 volt
3 volt 4µF 2 volt 161,íF 25 volt
6 volt !0µF 2 volt 32µF 25 volt
6 volt 20µF 2 volt 2µF 30 volt
6 volt 25µF 2 volt 160 30 volt
6 volt 30µF 2 volt 25µF 30 volt
6 volt lµF 5 volt 1µF SO volt
6 volt 2µF 5 volt 5µF 70 volt
All the above at 112 each.
320µF 2.5 volt 250µF 15 volt 150µF 25 volt
200).íF 3 volt 500µF I S volt 100µF 30 volt
250µF 6 volt 100µF 18 volt 2000,F 30 volt
400µF 6 volt 641í.F 25 volt 50µf 150 volt
All the above at 116 each.
I,000pF 6 volt 750µF 15 volt 1,0000 25 volt
1,000µF 12 volt 1,000µF 15 volt 500µF 50 volt
4,000µF 12 volt 500;.íF 25 volt 1,0000 50 volt
All the above at 2/- each.
2001100uF, 257V or 200 /200µf, 275V ... ... ... 616 each
CONDENSERS
Silver Mica, 3.3pF to 6,B00pF. Including High Voltage Disc
Ceramics (normally 31- each) F, OOSµFO'. per and
Paper Condensers: 00010, .001 /F, 002µ u
04µF, all at 716 per 100. E3 per 1,000; 1µF, 25µF, 5µF,
101- per 100.
RESISTORS Ipl. per 100
I /10th, I /6th, 1 /4th, }watt ... ..
Mixed wattages } watt to 3 watt. Close Tolerance. Assorted
Values. Polythene wrapped on cards of 10. Give -away
price, 501- per 1.000, plus 51- post and packing.
TRANSISTORS (At a price you can afford)
OC71 equivalent, I1- each, 25 for LI, 100 for O.
NKTI24 or NKTI2S. Switching transistors. V- each, 6 for 101 -
Large Car Radio type Output Transistors, 0C25, 0C35,
NKT40S, 10 /- each.
Packet containing: three 2G417, two 2G371, one 2G381, one
2G339, one diode (for making superhet with complementary
symmetry transformerless output stage) LI complete
Diodes, Ile each. Zener Diodes, ZEI2, ZB4.3, 51- each.
BY100 Mains Rectifiers for TV Sets. 716 each.
SIGNAL INJECTOR. R.F. /I.F. /A.F. Transistors, com-
ponents and circuit to make. Only 101 complete.
LOUDSPEAKERS. Brand New, 4 inch. Excellent
reproduction. 10I- each.
Midget Earpieces, complete with plug and lead ... SI- each
Magnetic Lapel Microphone with plug and lead 101-
each
Transistor Holders ... . .. ...
Miniature Soldering Irons, complete With Bit ... 301- each
Set of 5 assorted Bits to suit any job ... ... 201- set
WALKIE- TALKIES, 3- transistor, per pair ... ... £9.17.6
Crystal Set kits
POCKET -SIZE MULTIMETERS. AC /DC /Ohms ... .. E3
Transistor Intercomm. Units... ... 551- pair
FLUORESCENT
wth choke landh r
state 321íhCarrriagen101- perrft fitting.
ACOS Pth Kprice you would expect T
to pay for the needles
only! ul-
Stereo ... ... ... ... ... ...
Diamond Stereo
Will fit most record changers. Can be very profitable!
RELAYS
700 ohm or 2,500 ohm coil. Transparent dust cover. 2 pairs
of change -over contacts. PLUG -IN TYPE. Base included
in price. 251- each.
For orders less than IOr- please add Ed towards postage.
G. F. MILWARD
17 PEEL CLOSE, DRAYTON BASSETT
Near TAMWORTH, STAFFORDSHIRE
Tamworth 2321 Post only
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
Cover
This is best made from brass or aluminium,
although any other non -ferrous metal will do.
Again the gauge is not important and anything
between 22 and 28s.w.g. would be quite satisfac-
tory. Bend as shown in Fig. 4 by the dotted lines
and when the unit is finally complete the small
lugs can be bent under the base to hold the cover
in position. Screened microphone cable is used
to connect to a suitable amplifier.
234-
''Bend up along
dotted lines
0
1-
Lead -in
hole
Fig. 4: Cover of the pick -up made from non -ferrous metal.
675
COMPONENTS
3 Eclipse +in. button magnets.
3 fin. x 4BA brass countersunk screws and nuts.
1 piece of fin. Perspex lin. x 21in.
1 piece 22s.w.g. aluminium 4in. x 3in.
1 bobbin of enamelled copper wire 38-46 s.w.g.
Gummed paper, celluloid and screened cable,
etc.
Concluding Notes
Due to the lack of d.c. current in the coil
windings the signal strength is naturally very weak
and an amplifier with a suitable preamplifier stage
such as an EF86 is virtually essential. Satisfactory
testing can be carried out by connecting to the
pick -up terminals of most radio sets, although the
volume control will need to be turned full on. The
distance between the unit top and the strings
should not be too great for maximum effect and
the sound can be varied by altering the position
of the unit. The nearer to the fingerboard the
more mellow the tone, whilst if placed near to the
bridge a more staccato tone is obtained. In this
connection two or more units can be used to good
effect if suitably switched.
It will be seen that no details have been given
for mounting the unit as this will depend on the
type of guitar used and, of course, how far the
prospective user is prepared to go in drilling the
soundbox, etc., of his instrument. 0
A Thumbnail History of Radio -continued from page 671
him from his colleagues in his former days at
Writtle. He remained with the BBC until his
death in 1948.
The next few years were to witness the gradual
expansion of broadcasting in the regional scheme
with greatly increased powers and in 1929
Brookman's Park transmitter was opened, its four
power units each capable of delivering 200kc /s.
It was Eckersley's brainchild and remained in
service until 1963 almost without modification.
Advertising Charlatanism
With broadcasting came a wave of advertising
charlatanism almost unparalleled in history. You
could not hope to hear The Hague concerts clearly
unless you used so- and -so's high -grade coils.
Crystals capable of operating six pairs of ear-
phones from the power received from Continental
stations figured prominently. One firm of loud-
speaker manufacturers committed an almighty
howler, their illustration showing a concert pianist
hammering a grand piano, drawn the wrong way
round so that the bass strings were on the right -
hand side! Another firm manufactured a wonder-
ful high -frequency amplifying valve which
consumed "absolutely no current "; the envelope
contained only a small condenser between the grid
and anode pins. Numerous circuits appeared,
often differing little except in name. These were
the days when the field of technical authorship had
a large element of ex -Army men calling them-
selves captain! An impressive title in those days.
Reflex circuits using valve and crystal combina-
tions were popular for economic reasons, while
the more daring enthusiasts could experiment with
the Armstrong Superregenerative and Flewelling
circuits. By the end of 1923 the crystal was
steadily giving way to the valve in the home.
Mr. W. S. Barrel published details of a supersonic
heterodyne late in 1923.
Using only single tuned i.f. circuits, Mr. Ken
Alford, G2DX, the British pioneer amateur, pub-
lished details of his superhet early in 1924. He
was also the first to patent the r.f. stage to improve
the performance of the frequency changer and
reduce second channel interference, but he never
received any royalties and the big companies used
the idea.
This was the time of the great pioneer work by
amateurs on short waves, but this is another story.
Most home constructors were still thrilled to
receive the Savoy Orpheans or John Henry from
2L0, which now ran a power of 1fkW. BBC
stations were also operating in Birmingham,
Cardiff, Manchester, Newcastle and Glasgow, all
worked on a power of 1 1kW, and could be heard
on a crystal set within 20 miles provided the aerial
and earth system was. good. R
www.americanradiohistory.com
676 PRACTICAL WIRELESS December, 1%5
role
-"E611,404e
AN EFFICIENT
EARTH SYSTEM
i BY ALAN FORD 1
IN the early days of radio the installation of an
efficient aerial and earth system was considered
of paramount importance but in these times of
super -sensitive receivers which require neither
aerial nor earth the art has died somewhat.
However, the serious short -wave enthusiast and
particularly the transmitting amateur must still
attend to these points.
From time to time excellent articles appear
dealing with the design of short -wave aerials. It
is usually assumed that the reader will arrange for
a high -efficiency earth where this is required. It
is the writer's experience that few enthusiasts take
much trouble over the earth system and the
effectiveness of the whole arrangement suffers in
consequence.
The earth itself and the sea is a conductor. In
theory it has a negligible resistance, since its area
is so vast. However, connection from the
wAk
(a) (b)
Fig. la: The area'of contact of the usual earth rod is 2arh.
For the usual rod fin. thick and 36in. long, this is 56 sq.in.
I b: The area of a metal tank is obviously much greater,
even if the tank was 6in. x 6in. x 6in. The surface area
would be 216 sq.in.
receiving or transmitting apparatus is made usually
only at one point and the effective resistance
depends upon this. If the earth connection
consists only of the familiar rod in the ground,
conduction can obviously take place only between
its surface and the area of soil immediately
surrounding it. This area of contact is not very
large (see Fig. 1).
Until recently rising water mains provided a
somewhat better proposition than a simple rod.
However, plastic sheathing materials and poly-
thene connections now in general use preclude this.
It is, of course, illegal to use any gas piping as an
earth connection. What is needed is some method
of presenting a large area of contact to the
surrounding earth. Odd sheets of metal bonded
together and buried would be effective but an ideal
solution presents itself in the shape of a domestic
water tank.
A local builder or plumber will gladly part with
a faulty tank he has replaced or, failing this, a
demolition contractor is unlikely to get through a
week without finding one on his hands. The usual
size of domestic water tank is around 4ft it 4ft x
Mt, which gives an outside surface area of
80 square feet or even greater for the open -top
type. This is obviously a vast improvement on
the usual rod.
Importance of Site
The site for the earth is also of importance.
Apart from the question of a convenient place to
dig a 4ft to 5ft hole two factors should be borne
in mind. First, if possible, an area of fairly moist
soil should be chosen where the types of soil in
the garden vary. Secondly, and more important,
the earth connection to the apparatus must be as
short and direct as possible or there will be
considerable risk of stray resonant effects which
in the case of transmitting systems could cause
interference to television reception in the area.
Having chosen the site a great deal of digging
-continued on page 679
These surfaces
thoroughly cleaned
and then bolted
together
Fig. 2: Method of connection to the tank. The joint must be
completely covered with bitumattic point.
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 677
MINIATURE OSCILLOSCOPE
PART TWO BY H. T. KITCHEN
The Metalwork
Before the metalwork is started on a check
should be made to see if the components to be
used will fit into the stated dimensions. The
potentiometers and the timebase switch should not
exceed 1 }in. diameter with the exception of the
Y shift and X gain controls, which must not
exceed tin. If sufficiently small controls cannot be
obtained a suitable increase in the stated
dimensions will have to be made. In order to
keep the overall size down a c.r.t. base was
dispensed with and all leads going to the c.r.t. were
soldered directly to their respective pins. (It was
afterwards discovered that a suitable base was
unobtainable locally anyway!) This is quite safe
provided a good, hot, clean iron is used and all
joints made in the minimum of time.
The material used is 20 s.w.g. aluminium to the
dimensions given in Figs. 5 and 6. It is easier to
drill or file all the holes before the bends are
made, due allowance being made for material
thickness. The dimensions of the under -chassis
screen are not given, since it should be easily
fabricated. It is bolted to the chassis and front
and rear panels, resulting in a light yet rigid
assembly. Part of the front end will have to be
2'2
2'z
contoured to fit the neck of the c.r.t., the minimum
amount of metal being cut away so that it can
perform its function as an electrical screen
between the Y amplifier and the t.b. The sawtuoth
voltages generated by the t.b. have fairly large
amplitudes and without this screen would
completely block the Y amplifier.
The power supply section can be built in any
convenient form and positioned a safe distance,
magnetically speaking, from the oscilloscope
proper and connected to by means of a multi -way
cable.
Wiring Up
No layout drawings are given, since the method
of construction will be apparent from the
photographs. Two long tag strips either side of
the dividing screen and the components are wired
from these strips to the valvéholders or, in some
cases, from tag to tag or valveholder to valve -
holder. A small hole is drilled in the dividing
screen in line with VI and V4 to allow the sync
o/p from VI to be passed via C7 to V4.
Although the experienced constructor should
have little trouble getting the oscilloscope to work
satisfactorily the writer feels that this design, due
I 2'-y+---- 2' Z p
T-} 7 AO-
1 1:2_,.L--
.?;A
AO
! O
Ap-I
.4".1;11 134;
y
Bend up along dotted lines/.
.I-
'D' Four 6BA clearance holes for
-1 attaching chassis to panels
1 4
"A" Sig dia
"B" To suit co -ax socket
"C Sedia
I i
- ! Bend -up
along t
k_____4,.] dotted
lines ,
Fig. 5: Front panel (I.) rear panel (r.i.
www.americanradiohistory.com
PRACTICAL WIRELESS
'
2
T --A--O
I
9sß
December, 1965
- r
I Bend up
-1--+i -- /e
' I!
L
±Ö'A
'A' Holes media for grommets
Holes Vtdia for B9A valveholders
"C' Two holes 6BA clear. for bolting c
"D" Two holes 6BA clear. for bolting c
hassis to front panel
hassis to rear panel
1'e
T
o
Bend up
Fig. 6: Chassis drilling dimensions.
several minutes warming -up time it should be
possible to resolve a fairly fine trace by adjusting
the brilliance and focus controls. Operating the
Y shift control should cause the trace to move up
or down just within the aperture limits, whilst if
the trace is horizontally displaced a slight
adjustment to the value of either R32 or R33
should centralise it. Operating the timebase at its
slowest speed should cause the spot to traverse the
c.r.t. from left to right. If not, transposing the
leads from the o/p stage to the X plates should
bring about correct traverse.
A square wave is the best possible way of setting
up TCI, which should be adjusted so that neither
sag nor overshoot is apparent. It is essential to
set up TCI with the probe in " working order "
to its compact nature, should not be attempted by
the beginner.
The probe should be built into a metal can to
provide screening. A 35mm film container would
be ideal and should be lined internally with
insulating material so that if the contents do move
no great damage is done. The cable connecting
the probe to the oscilloscope should be good -
quality low -loss coaxial permanently attached to
the probe, since cables of varying length or quality
(hence internal capacitance) will alter the strays
and thus affect the " picture of quality ".
Testing
When wiring up is completed the oscilloscope
can be checked for correct operation. After
OA
4"
Fig. 7: Wiring diagram of the timebase unit.
Note:Tags marked'MÇ are
earthing points to chassis
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 679
Fig. 8: Wiring diagram of the Y- amplifier unit.
with its cap or lid firmly fastened, which will
probably require several attempts.
The surplus equivalent of the GEC E4205 -B -7
is the VCR139, which in the author's experience is
a variable tube, variable in the sense that some
specimens are good and others not so good, which
means that some experiment with the focusing and
brilliance values may be necessary. There is also
a possibility that some specimens may be averse
to direct coupling, though this is rather a remote
possibility.
AN EFFICIENT EARTH SYSTEM -continued from page 676
will be necessary. It takes a surprising amount
of time and energy to dig a hole of about 50 cubic
feet! It is very difficult to do the job tidily but
in the case where the chosen site is under a lawn,
for instance, some careful planning is worth while.
A sheet of canvas laid over the area of lawn
surrounding the site will prevent the excavated
earth from ruining the appearance of the grass.
The lawn should be sliced off in turves which can
be carefully replaced when the tank is buried.
Soil Packing
The tank itself should be prepared by removing
or tightening any loose rivets and attaching a
really stout connection of copper strip, about lin.
x fin., of the kind used as busbars on large
switchboards is suitable. Ordinary connecting
wire is hardly satisfactory-it will corrode in time
and a secure connection to the tank is difficult to
make. About bin. at the end of the strip should
be filed and rubbed down until it is bright and
clean and a corresponding area at the top of the
tank should be similarly prepared (see Fig. 2). The
strip should be bolted to the tank, using half a
dozen stout bolts, tightening to the limit. The
whole joint should be covered with bitumastic
paint to prevent corrosion. The hole should be
deep enough for the top of the tank to be about
a foot below the surface.
Preparation of the Tank
When the tank has been lowered into the hole,
soil should be packed tightly round it and also
Wtndow
Aerial
feeder
Feed -through
terminals
Spark gap Earth
strip
Fig. 3: Discharge gap to protect apparatus from lightning
damage.
inside if the tank has an open top! The copper
strip can then be routed by the most direct path
possible to where the apparatus is installed.
It will probably be found most convenient to
lead the strip in through a window frame and
along the back of the operating bench. The
connections from transmitters, receivers or aerial
tuning units can be made to large terminals bolted
to the strip. An earth system of this kind is very
suitable for lightning protection. The feeder from
the aerial may be brought to feed through
insulators near to the earth bar and another pair
of strips arranged as a discharge gap (see Fig. 3).
www.americanradiohistory.com
680 PRACTICAL WIRELESS December, 1965
on the
Short Waves
MONTHLY NEWS FOR DX LISTENERS
All times are in G.M.T. All frequencies are in kc /s.
The Broadcast Bands -by john Guttridge
RECEPTION conditions recently point to things
being little better this winter than last, very few
ssstations now being left in the 19m.b. after 2000.
The lower frequency bands are also again suffering
from severe overcrowding. One of worst offenders in
this respect is Radio Moscow which continues to
poach on other stations' established channels regard-
less of whether it puts in a stronger signal or just causes
an annoying heterodyne. Now to station news.
Germany (East): Radio Berlin International
(Berlin -Oberschoweide, Nalepastrasse 18 -50) now
broadcasts English to Europe at 1730 -1800 on
6,080/6,115/7,300 /9,730, 2015 -2045 as 1730 plus
1,511, and 2300 -2330 on 6,115/7,300/1,430.
Holland: Radio Nederland (P.O. B.222, Hilversum)
airs the Happy Station programme in English on
Sundays at 0730 -0850 on 9,715/17,830; 1030 -1150
5,980/6,025/9,715; 1400 -15206,025/15,425 / and 1530
-1650 on 17,810/21,570.
Poland: Radio Warsaw (Al Niedpodleglosci 75/77,
Warsaw) has English to Europe at 1830 -1900, 1930-
2000, 2130 -2200 on 6,135/7,125; 2030 -2100 5,950/
7,145; 2230 -2300 7,270/9,540/1,502 and 2303 -2330
on 227.
Rumania: Radio Bucharest (P.O.B.111, Bucharest)
is offering a diploma and badge to the first 1000
listeners to send in 12 reception reports within three
months.
Sweden: Radio Sweden (Box 955, Stockholm 1)
English transmissions subject to recent frequency
changes are 1230 -1300 11,810/15,195; 1400 -1430
15,420/9,620; 1445 -1515 11,915/15,315; 1615 -1700
11,705; 0145 -0215 9,705; 0315 -0345 9,705.
Vatican: Vatican Radio now has English to Europe
at 1500 on 15,120/11,740/9,645 /1,529 and 1815 on
9,645/7,250/6,190 /1,529.
Angola: Emissora Official de Angola (C.P.1321,
Luanda) has English from 1705 -1745 on 7,235/9,535.
Has ordered four 100kW Tx to come into operation
next year.
Radio Commercial de Angola (Casilla Postale 269,
Sa da Bandeira) transmits as follows: On 3,995 1900-
2200, 4,795 0530 -0900, 1600 -1855; 7,155 1030-
1300.
Bechuanaland: Radio Station ZND, (P.O. Box 63,
Lobatsi) is now using the new Gaberones station from
1530 -1700 on 3,356. Mondays to Fridays there is
pews in English at 1600.
Congo: Radiodiffusion de la Republique Democrat ique
du Congo, (Boite Postale 3171, Leopoldville). The
National programme is transmitted from 0400 -0730
(0900 Sundays) on 7,170/4,735/4,880 /11,795; 1000-
1300 (1500 Sundays) 7,170/11,795; 1500 -2300 4,735/
7,170/11,795. There is news in English at 0445,0545,
0645, 1045, 1145, 1245, 1645, 1845, 2045 and 2200. A
regional programme is also carried on 4,880.
Radio Interprovinciale du Katanga (Boite Postale
7296, Elisabethville) transmits from 0400 -0700 (0800
Sundays) 1000 -1200 (1300 Saturdays and Sundays)
and 1430 -2000 on 5,958.
Radio Bakwanga uses 7,295 from 1000 -1200 and
1600 -1900.
Radiodiffusion UFAC, (Boite Postale 97, Elisabeth -
ville), has English from 1600 -1700 on 4,890.
Ghana: Radio Ghana, (Broadcasting House, P.O.
Box 1633, Accra) is now using its new 250kW trans-
mitters. New English transmissions are 0430 -0515
and 0600 -0645 on 9,760; 0645-0730 on 9,545; 1645
-1730 and 1815 -1900 on 15,285 and 1500 -1545 on
21,720. A large new QSL giving all details is now
being issued.
Mauritius: Mauritius Broadcasting Corporation,
( Malherbes Transmitter Building, Forest Side) some-
times uses 9,710 from 0230 -1830. Normally 4,850
is scheduled for use from 1300 -1830.
Nigeria: Nigerian Broadcasting Corporation (Broad-
casting House, Lagos) will not QSL through bureaux.
English external service transmissions are at 1500-
1600, 1700 -1900, 2100 -2200 on 7,275/9,690/11,900 /
15,255.
Somalia: Radio Mogadiscio, (Mogadiscio) has re-
placed 7,160 by 7,130. English is at 0345 -0400 and
1800 -1830.
Spanish Guinea: Emisora de Radiodifusion Santa
Isabel, (Apartments 195, Santa Isabel, Fernando Poo)
has been heard closing down at 2300 on 6,247.
South Africa: Radio South Africa (P.O. Box 8606, -
Johannesburg) should now be using its new 250kW
transmitters. The Africa service schedule is now 0300
-0400 6,150/7,270; 1000 -1300 15,220/17,805; 1300
-1655 15,220/11,900; 1655 -1800 9,525/11,900; 1800
-2115 9,525/7,270.
Iran: Radio Iran (Ministry of Information, Meydan
Ark, Tehran) now announces frequencies of 7,135/
11,730 for its Foreign Service. It has been heard
however on a measured frequency of 11,790 during
the 2000 -2030 English broadcast.
India: All India Radio (New Delhi) now uses 9,665/
11,780/15,105/17,855 for its 1000 -1100 English trans-
mission to Asia. At the same time this transmission
can also be heard on 11,710/15,165 directed to
Australasia.
Finally a composite thanks to all who provided
information this month. Any information on South
American stations would be appreciated. At present
this appears to be a much neglected area.
www.americanradiohistory.com
DECemller, 1965 PRACTICAL WIRELESS 681
AR QUALITY
ANOTHER CODAR TRIUMPH!.
THE NEW 1880 CR.70A COMMUNICATION RECEIVER.
This completely new receiver sets a new high standard for
performance and finish unequalled at the price, and is a worthy
additlonto theoutstandingra ngeofCODAR qualitycommuni-
cation ag rang
/me
res) n uo/e 1.5 dé 55 éc/ Mc/s-4.2
I(rlr; 11.5
ranges: /0 u. scales
band calibrated in frequencies plus an additional logging
scale in degrees. Two speed vernier tuning control with reverse
slow tune action. Unique aerial Input stage exclusive to the
CR.70A employing High 'Q' Air- spaced CODAR -QOIL Inductor
giving extremely high gain with low noise level. Panel aerial
trimmer for peaking weak signals. Double tuned I.F. Iron
cored transformers. 470 Kots with EF183 frame grid valve for
maximum gain and selectivity. 5 valves (Including two twin
SSE) reception.7Callibrlineup.
te nall
Separate eenh B.F.O. stage for illumin-
ated. Automatic ngVolume control. Panel phone jack for
'Matcvhing unit optional extra). Superb styling, metal cabinet
a .Ó av Sablt s t fsFor
A.0 / Ready built. lustre finish. t a the fantastic low
price of $19.10.0. Carr. 7/6. (Delivery December).
CODAR R.F. PRE -SELECTOR MODEL P.R.30, Consider-
ably Improves the performance of any superhet receiver over
1.5- 30Mc /s. Uses EF183 Frame Grid Valve. and provides up to
20dB gain plus substantial image rejection. improved signal/
noise ratio and selectivity. Selector switch for either dipole or
H,T.16. vo ts..3 amp L.T. Sizer83 x 5 x 4in. Ready built complete
R.30X. Self plugs and instructions. 200 -2á0v. A Carr. so provides
25mA at 200v. H. T. and 6.3v. 1 amp L.T. for Other accessories.
57.4.0. Carr. 3/6.
CODAR Q" MULTIPLIER MODEL R.Q.10. For use with
any superhet receiver with an I.F. between 450 and 470 Kole.
Provides considerable increase in selectivity for either peaking
or rejecting a signal on AM. CW. or SSB. BFO. Size 8i x 5 x 4in.
Power requirements 180 -250v. H.T. at 5mA 6.3v..3 amp L.T.
Ready built complete with cables, plugs and instructions.
411.15.0. Carr. 3/6. MODEL R.Q.10X. Self powered version for
200 -250v. A.C. and also provides 25mA at 200v. H.T. and 6.3v. 1
amp. L.T. for other accessories 48.8.0. Carriage 3/6.
newest mos compact AtraannsmitttBAND foor fixed orr mobile M use on
160.8Ometres. "The tiny TX with the BIG voice ". Size only
8t x 5 z 41a. (Base area is less than two- thirds of this page!
High stability
to 4 Mc /s type calibrated
Air spat d Mc/s and Pi- Pi-net
output, P.A. Plate current meter plus neon indicator. Plate -
Screen modulator. AM /CW switch and Panel key jack. Plug
changeover for 8 or 12 volts heater supply. Ready built 416.10.0.
Carr. 4/ -. A.T.a POWER SUPPLY UNITS. For 200(250v A.C.
and 12v. Solid state for Mobile use, complete with all Transmit/
Receive changeover switching available.
CODAR -KIT CR.45K MAINS T.R.F. SHORT -WAVE RE-
CEIVER. World wide reception -North and South America,
Russia, India Australia, Far East. Amateurs, Shipping, eta
*Separate electrical bandspread. *3 slow motion vernier
drives. *Low loss polystyrene plug -in eofls, factory aligned.
*Dlais calibrated In frequencies and degrees. *Power output
3 watts for 2/3 ohm speaker. *Valve line -up: ECC81, EL84.
EZ80. Size 12 x 51 z Tin. CODAR -KIT CR.45K complete with
valves. 3 coils (10 -28, 25 -75.60 -178 metres) and 11 page instruction
manual, 29.10.0. Carr, 5/6. Extra coils 4/9 each. Instruction
manual only 4/- (credited on order). (Can now be supplied
ready built -price on request).
CODAR -KIT MINI- CLIPPER -OUR FAMOUS SHORT -
switch ontand bring the Wo be to your one at ready 1 w
cost. *Supplied complete with valve, one coil 25 -75 metres and
4-page instruction manual. PRICE 39/6. Carr. 3/ -. Extra Coils
4/9 each. Instruction Manual only 21- (credited on order).
Electrical Bandspread available. Provision to add 2 transistor
amplifier.
SEND 6d. IN STAMPS FOR ILLUS, LEAFLETS OF THE CODAR RANGE H.P. TERMS AVAILABLE WORLD-WIDE MAIL ORDER SEEVI
CODAR RADIO COMPANY
BANK HOUSE, SOUTHWICK SQUARE
SOUTHWICK, SUSSEX. Tel. 3149
G3IRE G3HGQ
Canada: Coder Radio of Canada, Tweed, Oneida
www.americanradiohistory.com
682 PRACTICAL WIRELESS December, 1965
EXPRESS ELECTRONICS
32 SOUTH END, CROYDON, SURREY
Telephone: Croydon 9186
FOR THE FOLLOWING BRAND NEW UNITS
AMPLIFIERS
TRIPLETONE HI -FI MAJOR 12 watt
TRIPLETONE CONVERTIBLE 5 watt
TRIPLETONE GEMINI STEREO 5 watt
LINEAR ... 3 watt
LINEAR DIATONIC ... 12 watt
LINEAR CONCHORD ... 30 watt
ADASTRA 3 -3 ... ... 4 watt
LEAK TLI2 ... 14 watt
LEAK VARiSLOPE PRE -AMP
LEAK TL50... ... ... 50 watt
QUAD .. 15 watt
QUAD STEREO /MONO PRE -AMP ...
LOUDSPEAKERS
GOODMANS AXIETTE 8in. 6 watt ... ...
GOODMANS AXIOM IOin. 10 watt ... ...
GOODMANS AXIOM 201 15 watt ...
:Jr
4:III
0110 xm
"Zan 1III
axu
Mullard
MAINTENANCE
MANUAL
Service Engineers will find the latest
edition of the MULLARD MAINTEN-
ANCE MANUAL an essential source of
information on all current replacement
valves, semiconductors and cathode
ray tubes.
It includes comprehensive data on over
200 types. The equivalents list provides
cross references to over 500 types.
Supplementary data sheets, on new
types are issued periodically and are
included in the initial price of 16/ -.
Applications for this service should be
made direct to:
MULLARD LIMITED,
MULLARD HOUSE,
TORRINGTON PLACE,
LONDON W.C.1.
BAKERS 'SELHURST' 3 or 15 ohm
JUNIOR 8in. ... ... 8 watt foam ...
STALWART 12in.... ... 15 watt ... ...
BASS GUITAR 12ín. 25 watt ... ...
STANDARD Heavy Duty 12m. 20 watt ...
BASS Heavy Duty 12ín. ... 25 watt ...
AUDITORIUM ISin. ... 35 watt ...
LI5.I8.6
E6.19.6
E15.15.0
E6. 6.0
£ 12.12.0
£16.16.0
£4.19.6
£18.18.0
E15.15.0
E33.12.0
L22. 1.0
L25. 0.0
E5. 5.0
E6. 6.0
E10.15.0
E5. 5.0
£5. 5.0
ES. 5.0
O. 7.0
E12.12.0
£18.18.0
RECORD PLAYERS
GARRARD SRPIO 4 -speed .. ... ... £4.17.6
GARRARD MODEL 1000 4 -speed ... .. £6.19.6
GARRARD AT6 TRANSCRIPTION ... £9.17.6
GARRARD 4HF TRANSCRIPTION ... ... LI4.17.6
GARRARD A LAB SERIES ... £17.10.0
GARRARD 301 LAB SERIES .. L19. 5.0
DECCADEC WITH DERAM HEAD £14.15.0
BSR TAPE -DECKS TD2 Twin Track ... . ... E7. 9.6
De -Luxe record players with excellent sound reproduction
incorporating the latest BSR 4 -speed autochanger, independent
tone and volume controls, high quality speaker. Not in kit form
but factory made and tested. Finished in most attractive two -tone
cabinets in blue -grey, red¡ grey or charcoaligrey with gilt trim.
200 -250v. AC. £12.12.0.
Delivered free U.K. S.A.E. enquiries
HOME RADIO (Mitcham) LTD.
187 London Road, Mitcham, Surrey
Phone: M17cham 3282
One of the most interesting sections of our
Components Catalogue is the KITS SECTION,
which runs to 14 pages listing 169 different
items. Here is an extract from the page
dealing with RADIONIC KITS...
'Designed for both the beginner (aged 10 and upwards)
and the expert in electronics. The only tools required are
the spanner and a pair of scissors. Build and rebuild as
often as you wish and check circuit at a glance through the
transparent panel. Extra components can be purchased to
expand sets as required. Adopted by Universities,
Technical Colleges, Schools and the Armed Forces for
electronics training."
KT46
KT48
KTSO
KTS2
f h
or ear
Set No. I. Fourteen different circuits can be made, including regenerative receivers p one
£5.18.6
operation.
Set No. 2. Twenty different circuits. T.R.F. and Reflex receivers. £6.19.6
Set No. 3. Twenty -two different circuits, including microphone and pick -up amplifiers and re eiver
for loudspeaker operation.
Set No. 4. Twenty -six different circuits,
including a 6- transistor super- heterodyne
receiver. £14.19.6
Would you like to see the other 209 pages, listing
5,800 items, 900 of them illustrated, plus a 21 -page
supplement and a Semi -Conductor Centre brochure?
Then post the coupon now with your cheque or P.O.
for 9/- (7/6 plus 1/6 P. & P.). Remember, every
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shilling when used as directed.
Please write your name and address in block capitals
NAME
ADDRESS
HOME RADIO LTD, Dept. PW, 187 LONDON ROAD. MITCHAM
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 683
The Amateur Bands -by David Gibson G3JDG
WE'LL soon be calling this the 'Twenty Metre
Column ". The activity on this band coupled
with the huge pile of 14Mc /s logs is quite
fantastic. Neither is there any need for expensive
equipment. All sorts of reports from all sorts of
gear coupled into an amazing variety of aerials.
One minute's silence, please, for the coathanger
gang; no reports at all from weird antennas this
month. What about a thin line of aluminium
paint down the side of the house fed at the
bottom?
From the logs that arrived it appears that a
superhet or an sxpensive communications job pulls
in no more than the t.r.f.s. How about a t.r.f.
versus superhet month? Don't be sceptical if you
own the latter or too pessimistic if you have the
former. When listeners with broadcast receivers
start sending in reports on New Zealand " hams"
running 100W or so anything might happen.
The l.f. bands, too, have brought some interest-
ing logs and these show that DX is not confined
to 14Mc /s. A special pat on the back to all the
1.8, 3.5 and 7Mc /s reporters; it's not as easy on
these bands as it is further up the r.f. spectrum
and digging out the DX requires a determined
effort and a sharp pair of ears.
The L.F. Bands
Barry Dale (Cheshire), t.r.f., 60ft long wire,
7.8Mc /s: ON4UN, 5A2TR. 3.5Mc /s: GC, HBO,
K2, K4, LA7, 0E, OH, OX, OZ, SM4, VE2, VOI,
W3, W4, WA4, WA9, YU. ZL4OM (New Zealand
at 0649hours), 4U3, 5A2, 9M4LP (Singapore).
7.0Mc /s: TG9, XE1, YV4, ZL2BCG. A very
fine log indeed. James Brown (Cardiff), " hotted
up" 19 set, 80m dipole. 3.5Mc /s: DJ, DL, EI,
FP8CA, G, GW, GI, GM, HBO, HB9, Il, K1,
0E6, OHO, OH2, OKI, ON4, OX5, OZ5, PAO,
SMI, SP7, VEI, VE3, VOI, VS6AJ (Hong Kong),
WI. W2, W2 /W1, 4U1, 4U4, 4U5, 4U6, 4X4.
J. Peterson (Bushey), home -brew transistor super -
het, 30ft wire around the loft, 3.5Mc /s, s.s.b.:
LA 57, OK 59, ON459 +, OZ2 59, XOIES 57,
VOlGO 57, ZB2AO 55.
R. ball (Worksop), SX28. 80ft long wire,
1.8Mc /s: KIPBW, VOIFB, W1BB /I, W2EQS,
W2IU. 3.5111c /s: VE3BWY, WIDBQ. WIGF,
W3FAK, W9KSE, WB2RQZ, WN ?SKF,
WN2TUU. WN4A!B, ZL2BCG. 7Mcls: CPIEA,
CP5EZ, HK4EX (Columbia), UA9DH, W6AM,
ZL2AWJ. 23968214 Harvey, C. (Chepstow), B.C.
receiver, 80m dipole, sends in a huge log of G,
GW, etc., heard on 3.5Mc /s with two interesting
specials, GB3RH and GB3SEE.
Twenty
John Fitzgerald (Great Missenden). Hitachi
WH837 eight- transistor broadcast receiver, 14Mc /s
doublet, sends in what can virtually be described
as a miniature edition of the 1965 call book. With
another receiver used as a b.f.o. John raised
CR4AJ, CR6BX, CR8AE, CR9AK, DUI AP,
DU6TY,' F9UC /FC, FG7XC, FM7WQ, FP8CA,
HI8XAJ, HK5AOH, HL9TO, HPIJC, JA6AD,
JA9IL, KL7EKB, LA8FG /P (Jan Meyen Islands),
MI B, MP4BCC (Bahrein Islands), PY2BZD /0
(Trinidade Island), TJ1AC, TU2AA, UAQEH
(Sakhalin Island), UM8FZ, VEI, 2, 3, 5, 6, VOI,
VEIAED /SU, VE3CVL /SU, VKIVK, VK2NN,
VK3AHO, VK4NR, VK5DT, VK9AG (Territory
of New Guinea). VP2KD, VS6AJ, WI, 2, 3, 4, 5,
8, 9, 0, WNWNV /8F3 (Indonesia), XEIJJJ,
XE3L, XW8AX, XZ2TZ (Burma), YAIAW,
ZLIKG, ZS3E, ZS40F, 4S71W, 4UISU, 4W2AA
(Yemen), 5T5AD, 5Z4FE, 9K2AM, 9M20V,
9M4LP, 9M6AP, 9M8KZ, 9NIMM (Nepal).
Heaven help us if he ever gets a beam antenna!
C. Pedder (Preston), R1155L, 40ft long wire,
BVIUSA (Formosa), CT, DU, G3BID /LX /M,
JA. KX6BQ, PY2BZD /0, VPZDO /MM (off
Perth, Western Australia), W6IBU /KG6, XW8AX,
XZ2TZ, 4U1, 5. 6, 9M4.
The new firm of Messrs. Dunning and Black
(Kent). HE30. 20m dipole, send in an impressive
list which includes CR4AJ (Cape Verde), DUTAA,
EA8CR (Canary Islands), FG7XL (Guadeloupe),
FP8CA, HPIJC, JA6 -AB, AD, BEE. NP,
JA8HK, KAIAA, KR6BQ (Okinawa), KZSBW,
MP4TBO. PJ2AA, PZJBW (Dutch Guiana),
TI2SS, VK4FJ, VK9NT, VP2SK, VP6WR,
VP7DI, XE2LR, XU1AA, ZB2AP, ZL2JO,
ZL3UY, 3A2CR (Monaco), 4UITTU, 4X4BW,
5A4TQ, 6Y5XG. D. J. Mortimer (Gloucester),
CR100 fed from a Band I and Band III television
aerial! (I just knew there'd be one somewhere.)
CR4Ai, FP8CA, HK2YO, JA6BEE, KG6AJ'S,
KJ6BZ, KL7EKB, KM6DJ, KR6GF, KOHGM/
KS6 (Samoa). KX6BQ, MP4TAV, OX3SE,
TF3EA, TJBAC (Cameroons), VK -2NN. 3AM,
3AHO, 4LB, 5DT, 6GC, VP2KJ, VS9AE, W6, W7,
XW8AX, YAIAW, ZPOBK, ZS60Y. 4S7IW
(Ceylon), 5X5FS. 5Z4GF, 6Y5RA, 7X2MD,
7Q7PBD, 9GIDY, 9J2FK, 9K2AM, 9M2SS,
9Q5QR.
F. Pemberton (Ricksmansworth), two -valve
battery t.r.f.. 154ft indoor aerial, KC6. KH6,
KH6 /KS6, KL7, KM6, TF2, UAO, VK, VU2,
WA6, W7, XE1, YV1. 4S7NE. David Blackwell
(Yeovil), home -brew 1V3, 20m dipole: CR4AJ,
FP8CA. (St. Pierre). JAIMP, KL7ESR. KM6DJ,
(1X3SE, PYISD, PZIBW, VP2KJ, VK -3AM,
6MN. 7CK. 9J0 (Cocos Keeling), 9WA. 9TN,
VU2CIC, ZS3E. 4X4JU. D. Griffiths (Ilford),
domes is receiver 6ft loaded whip, CR4, CR6,
ET3, F08. FP8, JA6, KP4. 005. PJ2, PY2 /SU,
VF3/SU, TU2, VK9, VS9, XW8, YAI, ZS5, 4W2,
9M2.
Fifteen and Ten
Nearly all 15m logs were from listeners already
reporting on other bands. B. Dale raised PY2,
ZS1, 2, 6, 5A1, 9G1, 9Q5, while R. Thal! netted
JAI, JA6, Kl JAM, PY2 /0, VS9. W5, ZD7, ZP5,
ZS2, 457, 4W2, 9F3. J. Fitzgerald raked in CR6,
-continued on page 702
www.americanradiohistory.com
684
A SIMPLE
PHONE
/, 30-BAND
TRANSMITTER
II I. f RATER
80IX
PRACTICAL WIRELESS December, 1965
T ffiS transmitter was built as a standby for
160 and 80m band working and is of very
simple design and construction. Very good
results have been obtained and the transmitter can
give a quite substantial radio frequency output,
well modulated.
From the circuit, Fig. 1, it will be seen that a
carbon microphone is used coupled to VI by the
transformer Tl. To avoid a battery, microphone
current is taken from the junction of R4 and RS.
Three different carbon microphones were tried
with this circuit and all were satisfactory. A 6L6
acts as modulator and can easily give adequate
modulation with an input of about 8 to 12W to
V3. T2 is a mains pentode speaker matching
transformer of fairly generous size, the secondary
being unused.
V3 has the output tank coil L2, which tunes to
both 160 and 80m bands. It is thus only necessary
Fig. I t Suitable power supply for the transmitter.
to insert a 160 or 80m band crystal and tune up
with VC1 and VC2 as described later.
Transmit /receive switching is included by the
three -pole two -way switch. Section A transfers
the aerial from the transmitter to the receiver.
Section B applies h.t. to the transmitter. Section C
earths the receiver aerial circuit on transmit.
Construction is very simple, the meter being on
the front chassis runner. The transmitter can be
built largely from surplus or old receiver -type
spares. It also lends itself readily to increasing its
scope by fitting either a harmonic oscillator to
drive the p.a. or by adding a v.f.o.
LI and L2
L1 is an anti- parasitic choke consisting of six
turns of 20 s.w.g. bare or enamelled wire about
gin. in diameter and $in. long. R7 is placed inside
it and a short connection goes from LI and R7 to
the cap clip for V3.
L2 is wound with 22 s.w.g. tinned copper or
enamelled wire on a 1 #in. diameter smooth or
ribbed former. There are 40 turns spaced to
occupy 2 #in. winding length. Some variation in
the diameter, length and wire gauge will be
unimportant provided the coil is subsequently
adjusted if this is necessary.
The anode tuning capacitor VC1 is a 500pF or
similar air -spaced variable component and should
not be a miniature type, which will have closely
spaced plates. The spacing of VC2 is not
important and it can be two -gang or three -gang.
Sections are connected in parallel, so the total will
be about 1,000pF for a two -gang capacitor and
1,500pF for a three -gang capacitor.
Chassis Dimensions
The exact layout is not likely to be very
important but a 12 x 5in. chassis is convenient and
parts can be located as in Fig. 2. The chassis is
3in. deep to accommodate the meter and T2.
The variable capacitors are bolted to the chassis
with their feet or brackets added for this purpose.
A bracket frorh VC1 supports L2'. RFC2 stands
vertically, a well- insulated lead passing down
www.americanradiohistory.com
December, 1965 PRACTICAL
through the chassis to meter negative.
Fig. 3 shows wiring and components under the
chassis. All points MC are tags securely bolted
down. Most leads can be run close against the
chassis or its side to avoid unnecessary pick -tip of
r.f. The trimmer TCI has one tag soldered to tag 3
of the 807 holder.
An adjustable washer cutter will do well to
make the meter hole. A 100mA tin. or similar
meter is most suitable but a 50mA instrument
could be used. If a more sensitive meter is to
hand it can be shunted to read 0- 100mA. If a
1mA meter is to read 100mA divide the meter
resistance by 99 to find the shunt value. For a
5mA meter divide the meter resistance by 19 to
find the shunt required. If the meter resistance is
not known adjust the shunt until the wanted range
is obtained as shown by comparison with a test
meter.
The rear runner was of insulated material but
any kind of insulated terminals or sockets will do
for aerial or microphone connections. If a coaxial
lead is to be used fit a coaxial socket to suit.
Power Supplies
Flexible leads run from the transmitter to the
power pack. For easy connecting use black for
chassis, red for h.t. positive and some other colour
for the heater circuit. The heaters are left on
while the equipment is in use in the customary
V1
eJ5
WIRELESS 685
manner. A suitable power pack-circuit is shown
in Fig. 4. An output of about 125mA at 275V
will do very well.
A 250V pack can be used but there is some
voltage drop in T2 and the p.a. anode voltage may
then be around 220V or so. To avoid unnecessary
loss of voltage T2 should be of quite low
resistance. A small or midget transformer is not
suitable here.
A power supply which can be pressed into
service may be to hand. Lower 'voltages will
naturally result in some drop in output for a given
p.a. anode current.
Testing
It is recommended that a first test is made by
connecting the aerial and earth terminals to a
lampholder in which a 240V or similar 15W lamp
is inserted. Close both VC1 and VC2 fully. A
160 or 80m band crystal should be placed in the
crystal holder.
When the transmitter is switched on. imme-
diately rotate VC1 until the meter shows a dip in
anode current. This will be to .a point .where the
meter indicates only a few milliamperes. To
increase this current slowly open VC2, meanwhile
retuning VC1 for minimum current. The. minimum
current or dip obtained with VC1 will become
higher as VC2 is opened and the lamp should
commence to light. Continue this until .the
RFC2
R H.T.f-
Aerial
5
C3
O01
yF
V2
6L6
Carbon
mic
o R3
470kL2 R4
toon
Transmit/
receive
switch
C9
O0O5yF
RI
3.3 C2
kn TSyF
C4
50yF
Fig. 2: Simple two -band phone transmitter circuit.
www.americanradiohistory.com
686 PRACTICAL WIRELESS December, 1965
i4---1H
2
14
Crystal
in holder
L1= 6turns gdla
3'4 long 20swg.
L2= 4Oturns 22swg.
1Y2dia 2q long
Chassis.
12"x 'x3
Fig. 3: Dimensions and
required input, as shown by the meter, is obtained.
If 250V is avail..ble at the anode of V3 an input
of 40mA corresponds to 10W and this must not
be exceeded in the 160m band. At this input the
15W lamp should light quite brightly. An input
of 10 -12W can be used in the 80m band.
With 160m crystals it will be found that VC1 is
almost fully closed. When 80m crystals are used
VC1 is well open. For the 160m band the crystal
frequency should be a little inside the 1.8Mc /s to
2Mc /s limits. For 80m the band is 3.5Mc /s to
3.8Mc /s but phone operation is usually in the
3.6Mc /s to 3.8Mc /s section. A check can be made
of the anode voltage of V3 with the valve drawing
",/ae// / //
positions of components.
the required current by applying the test meter
prods to chassis and negative on the 100mA meter. <
With the transmitter working into the lamp the
carrier should be easily located with the station
receiver. With the microphone connected speech
should sound clear and strong on the receiver.
Avoid strong feedback between the receiver loud-
speaker and the transmitter microphone or
howling will begin.
The voltage across R5 should suit most carbon
mike inserts and similar carbon microphones. The
microphone voltage can be reduced if necessary by
reducing the value of R5. At the same time
increase R4 so that R4 and R5 added together
/3/ /3 // / / c7
ip69Pir:i'ilie,:iqml@I Jf
Receiver aerial
terminal
Red
ó RFC2
holder
holder
Fig. 4: Wiring and components under the chassis.
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
give a total of about 170 to 2000. Should a 20012
potentiometer be to hand this is ideal as a
substitute for R4 and R5. The microphone can
be fed from the slider and the voltage can be
adjusted to any value needed.
Should the microphone prove to be too sensitive
this trouble can be removed by reducing the
voltage. A low voltage also tends to reduce any
hiss generated here.
Attempts to use too much audio will cause
distortion which can be heard in the station
receiver or confirmed by contacts. One advantage
of the Class A modulator, as used here, is that
audio distortion sets in instead of over -modulation
of the carrier.
The setting of TCI is not very important but a
check should be made here while testing the
transmitter. Initially TCI can be about half open.
Opening TCI to near minimum will cause some
loss of r.f. output, as shown by the lamp brilliance
falling, or a reduction of aerial current.
Aerials
For two -band working with the same aerial an
end -fed wire is popular. About 136ft is a good
length to use. This will present a high- impedance
load to the transmitter on 80m (half wave) and a
low- impedance load on 160m (quarter wave).
The output circuit will also load into many
other lengths but the feed impedance will be
different, so that the tuning positions for VC1 and
VC2 are changed.
If a tapped loading coil is used in series with the
aerial or an aerial tuner is added the transmitter
will operate into any length of wire from about
10ft. upwards. Adjusting the tappings on the
COMPONENTS LIST
Capacitors:
CI 25µF 25V
C2 25µF 25V
C3 0.011.1.F mica
C4 50µF 50V
CS 2000pF mica or ceramic
C6 2000pF mica or ceramic
C7 0.0I µF
C8 200pF mica or ceramic
C9 0.005µf mica
TCI 30pF beehive air -spaced
VCI 500pF variable (not miniature type)
VC2 2 -gang or 3 -gang 500pF each section
Resistors:
RI 3.3kí2 f watt RS 10012 I watt
R2 180k01 watt R6 20k0 I watt
R3 470kO f watt R7 330 I watt
R4 1000 I watt
Miscellaneous:
VI 6J5 V2 6L6 V3 807
Two octal holders. UX5 holder. Crystal holder.
160m or 80m band crystals.
TI Carbon mike transformer, about 1:50 ratio.
T2 IOOmA or similar 5kO primary output
transformer.
3 -pole 2 -way wafer switch. IOOmA meter.
Chassis 12 x 5 x Sin. deep.
RFCI 2.5mH RFC.
RFC2 2SmH 60mA RFC.
Three knobs. Terminals or socket strips, etc.
687
t
Ir
\C
.,
t
Ir
3'
Ir
3
t
Ir,
* UHF TEST OSCILLATOR -f
full constructional details1
* DOES THE AERIAL
MATCH ?
* SPOT WOBBLE
* REPETITIVE FAULTS
* TV SERVICING
* YOUR PROBLEMS SOLVED
These and many other interesting
articles appear in the November
issue of PRACTICAL TELEVISION
ON SALE NOW, price 2¡-
uí
1,
.JI
JI
:.
.Jl
,.
loading coil allows an impedance to be reached
which falls within the adjustment range of the
transmitter output circuit.
In other cases, if the load is very low, a 1,000pP
mica capacitor can be added across VC2. This is
most likely to be wanted when operating the
transmitter into a short aerial on 160m.
Good Earth Helpful
A good earth is generally helpful, especially
with short aerials. Should the aerial be near a
half -wave on the band in use the addition of the
earth can result in very little difference in signal
strength but when the aerial length is much less
than a half -wave the earth resistance should be
low. If a 350mA r.f. meter or similar instrument is
to hand this can be included in the aerial lead:
and readings can be noted. The current shown'
will largely depend on the aerial impedance and
thus on the aerial length. However, once the
readings are noted they will then show that the
accustomed r.f. output is being obtained on future
occasions. Should the aerial impedance he
particularly low the 350mA meter should be
replaced by one able to take a largos- current 1
4. www.americanradiohistory.com
A TRANSISTORISED
S.W.
THIS unit was first designed to enable a
relatively young, inexperienced constructor to
convert a fairly simple home -built medium -
wave receiver to bring in the popular short -wave
bands of 1.8- 2.0Mc /s and 3.5- 3.8Mc /s.
The design requirements were that the unit
should be simple to build and that it should be
easy to set up with the minimum of test
instruments. Over- riding these considerations was
the economic factor in that the converter had to
be built for less than £1. The reader may judge
for himself the success of the design in fulfilling
these requirements when it is stated that the unit
has been operating satisfactorily for the last 18
months and has left the builder with a surplus of
7s. 6d. on his original estimate.
A block diagram of the unit is shown in Fig. 1.
Now, since the main receiver was tuneable only
over the medium wave band, the r.f. output from
the converter had to lie in the region 0.6- 1.5Mc /s.
This meant that the oscillator frequency had to
be such that when it was beating with the
incoming signal at r.f. the resultant i.f. signal was
in this band.
For reasons of simplicity of construction and
ease of alignment it was decided that the local
oscillator would be crystal controlled. Since we
are operating over two bands this might suggest
that two crystals would be needed. However, in
the present design we are lucky in that we can
make one crystal do the work of two. If we make
the oscillator run at 2.6Mc /s, then should we wish
to tune an r.f. signal at 2.0Mc /s the i.f. output
would be at 0.6Mc /s and similarly the i.f. output
for a 1.8Mc /s signal the i.f. output will appear at
0-8Mc /s. Thus the band 1.8- 2.0Mc /s can be
covered easily by the broadcast receiver. If we
now consider the 3.5 to 3.8Mc /s band we can see
that, using the oscillator frequency of 2.6Mc /s, a
signal will appear at the converter output in the
range 0.9 to 12Mc /s. This is convenient for two
Output
to set
Fig. I: Block
diagram of the
short -wave converter.
CON'V
COMPONENTS LIST
Resistors:
RI 470k12
Capacitors:
CI 200pF
C2 5000pF
C3 330pF
Semiconductors:
Tr I OC45
Tr2 0C44
VCI 365pF variable
VC2 100pF variable
LI. L2,-1
L3, L4, -See coil table
L5, L6 ,
Miscellaneous:
Xtal holder (to suit). SI S.P.S.T. toggle. Printed
circuit board. 9v battery, etc.
reasons. It means that (1) we do not have to
switch a pair of crystals and (2) almost the whole
of the broadcast receiver scale is used in covering
these two bands, so that there is no scale overlap
and a smooth calibration over the scale may be
used if this is thought necessary.
The Theoretical Circuit
-The theoretical circuit of the converter is
shown in Fig. 2. The oscillator section is designed
around an 0C45 (Trl). The oscillator is crystal
controlled. the crystal being placed between the
base and collector of the transistor. The
collector current of the 0C45 is drawn through L3
which is tuned to the crystal frequency by Cl. The
purpose of C2 is to decouple the coil to earth thus
reducing the possibility of unwanted feed -back and
so enhancing stability.
The oscillator output is taken via L4 to the
emitter of Tr2. Tr2 is an 0C44 and serves the dual
purpose of an r.f. amplifier and mixer, and, by
virtue of the fact that it draws emitter current
through L4, it is coupled to the oscillator section.
The aerial is coupled by L2 to LI which is tuned
by VC2, the tuning capacitor. The tap on Ll is
used to match the base input impedance of the
transistor to that of the aerial coil. C3 is switched
across LI to provide the necessary tuning capaci-
tance for the lower frequency band. The com-
bined r.f. and local oscillator signals are in this
way amplified and appear across L5. this winding
being tuned by VC1 which is a " peaking" capaci-
tor. L6 is used to couple the converter to the main
set.
Construction
The construction of the circuit is fairly conven-
tional and the circuit would appear to ' he '
reasonably tolerant as to layout since experience
www.americanradiohistory.com
has shown that the unit functions well under
nearly all the possible configurations of the
components.
The circuit of the original was built up on an
" etched" circuit board -although more orthodox
methods will be equally satisfactory. It is not pro-
posed to go into the procedure of etching circuits
as this has been dealt with in previous issues of
this journal, suffice it to say that ample copper
should be left on the board for connection
purposes and the conducting strip should be well
cleaned before the soldering operation. An outline
template for the circuit board is shown in Fig. 3.
As can be seen from the layout, no attempt has
been made to miniaturise the circuit, but if the
reader wishes to do so he may well find that the
converter could be made much smaller and he
might discover that the unit will fit inside the case
of the basic receiver.
The crystal is of the standard type and this may
be purchased for a few shillings at many surplus
stores. It is, of course, not necessary to purchase
a crystal which will resonate at the exact frequency
specified as any frequency within the band, 2.5-
2.65Mc/s will prove satisfactory. Of course, if the
constructor is prepared to allow an overlap on the
receiver scale then crystals of frequencies other
than these may be used -provided that the final
output is within the frequency coverage of the
main set.
The coil winding details are given as Fig. 4.
sskt.'sw.;. .:
Fig. 3: Component layout on "etched circuit" board
The setting up and operation of the circuit is
quite simple. Having connected a suitable power
supply to the circuit a screened lead should be
connected from L6 to the receiver and an aerial
connected to the aerial socket on the converter.
The core of L2 is then set so that the top of the
core corresponds with the top of
the coil winding and VC2 is then
rotated until a signal is tuned in.
The core of L3 is then adjusted
for maximum response from the
converter and VC1 rotated until
the point of maximum response is
found. It should now be possible
to tune over the whole band -
peaking where necessary with VC1.
The gain over the whole coverage
should be even with no sharp
peaks or drops which cannot be
levelled out by adjusting VCI. If
this is not so, or if the whole of
the band cannot be covered, then
the core of L2 should be re -set and
C1 the operation repeated. When a
200pF satisfactory arrangement has been
found the converter should be
switched to the second band and
the operation repeated.
It may well be that the
optimum settings of the
-continued on page 722
VC1 L6 Output
H.T.-9V
b O
L
Crystal
Jsnnnr
R1
470k11 Tri
OC45
C2
T000pF
Fig. 2: The theoretical circuit.
www.americanradiohistory.com
690 PRACTICAL WIRELESS
CIRCUIT DISGUISES
THERE is a simple way of looking at circuits
that reduces much of their complexity. Many
of the differences that exist between circuits are
due to the way in which external connections are
made to them and especially the manner in
which the d.c. supplies are introduced.
Now, at a fundamental level, d.c. supplies do
not form part of the circuit. Although the circuit
usually draws most of its energy from a d.c. power
source it is essentially concerned with signal wave-
forms, i.e. with alternating currents and voltages.
Many of the circuits that seem to bear no
resemblance to each other are in fact alternative
arrangements of some basic network. Circuit
variatit ns are not, of course, merely for the
novelty. Different arrangements have their own
particular applications but the ability to analyse
and compare them gives one a valuable insight
into their working.
Basic Circuits
We can penetrate circuit disguises by recognising
that many of the components in the circuit are
there merely to pass or to block direct currents. It
is easy to distinguish these by their large values
and by their positions from the components upon
which the a.c. performance depends. If we redraw
the circuit diagrams, leaving out these components,
- we can derive the basic a.c. circuits and in the
process discover that some apparently unrelated
circuits are equivalent. The only components
retained, apart from valves or transistors, will be
'thibse concerned with tuning or with modifying the
frequency response and waveform.
As a first step we omit the battery or d.c. supply
and join together the positive and negative supply
lines, for these are essentially the same when only
a.c. conditions are considered, there being no
.alternating voltage between them. The next step
is to remove any choke, leaving an open circuit,
ta) Hartley (b) Colpltts
Fig. 1: Basic tuned oscillators.
December, 1965
BY R. LEYLAND
and to replace coupling and bypass capacitors with
short -circuits, i.e. to bridge each of them with a
direct connection. It will also be possible to
remove some of the associated resistors whose
function is to supply d.c. to the electrodes of the
valve or transistor.
Each circuit can have at least three alternative
forms according to whether the anode, grid or
cathode is earthed. If the variations are to be
strictly equivalent, however, they may require to
have a floating input or output, which is not
always feasible.
For instance, it can be mentioned briefly that the
Miller integrator, used in oscilloscope sweep
circuits, is equivalent to the cathode- follower
charging circuit and also to the Bootstrap
integrator, but neither of these alternative forms
is as useful. In these circuits, incidentally, a
direct voltage reference is needed which cannot be
omitted from the circuit.
However, the switching circuit which produces
the flyback converts this in effect to a step or
impulse input, so it is not the same thing as a
steady d.c. supply.
Tuned Oscillators
By applying these principles we can reduce
various oscillator circuits to a very simple
configuration (Fig. 1), the important point being
that the emitter of a transistor or the cathode of
a valve is connected to a tapping on the tuned
circuit and this may be on either the inductive or
the capacitive arm. There are, of course, many
other types of tuned oscillators, some employing
separate coupling coils, etc., but these will serve as
examples.
The combination of a coil and capacitor to form
a tuned circuit tends, through resonance, to main-
tain the oscillation at one particular frequency.
Part of the tuned circuit is between the grid and
cathode, and supplies an input to the valve. The
output from the valve is to the part of the circuit
that is between the anode and cathode and makes
good the circuit losses, so maintaining the
oscillation.
It is clear that the grid will receive an input
waveform that is opposite in phase to that on the
anode. Or we may say instead that the cathode
input is in phase with the anode. The valve itself,
of course, gives a corresponding phase reversal
between grid and anode, so that the feedback is
positive. There is no phase shift in the tuned
circuit at the frequency of oscillation.
A step -down of voltage occurs from the output
to the input and it is necessary to consider such
factors as the relative impedance levels of the
www.americanradiohistory.com
December, 1965
valve and tuned circuits and,
with transistors, the low input
impedance.
In some forms of Hartley
Circuit the way in which it is
usually drawn, with the cathode
tapped up on the coil, tends to
suggest that negative feedback is
present, but reference to the
basic circuit will show that only
. positive feedback is involved. It
is, however, possible to add
negative feedback to any of
these circuits by including a
resistor without a bypass
capacitor in the cathode lead or
in the emitter lead of a
transistor, where it is of
considerable assistance in con-
trolling the performance.
One point that emerges is that in oscillator
circuits the point chosen for grounding is often
merely a matter of convenience.
In amplifier stages, however, there are significant
differences between the different configurations,
involving interelectrode capacitances and also
negative feedback, whose presence in a grounded
emitter stage gives a more uniform high- frequency
performance.
Phase -Shift Oscillators
Phase -shift oscillators employing a single tran-
sistor, as in Fig. 2, require a high -gain transistor
because of the attentuation in the ladder network,
and a high load resistance will probably make
necessary a higher voltage supply than the usual
9V. It is, however, possible to use two transistors
in sequence to obtain a higher gain.
The arrangement shown at Fig. 2a is the
customary one and can be described as " grounded
emitter ". By separating the basic circuit,
however, we can attempt to transform it into a
grounded collector version.
As it was pointed out earlier, alternative
arrangements are sometimes less satisfactory,
requiring, for example, in a tuned oscillator the
inclusion of chokes, or having the disadvantage
PRACTICAL WIRELESS 691
(a) Groùnded emitter (b) Grounded collector
Fig. 2: Phase shift oscillators.
(a) Basic circuit
Fig. 3: Compound emitter -
followers.
that the moving vanes of a variable capacitor
cannot be earthed.
However, in this instance of a phase -shift
oscillator a grounded collector version can be
devised as in Fig. 2b. Unusual as the new circuit
looks it nevertheless works. Note the bootstrap
arrangement (CE, Rlb, Ric). This solves the
problem of base current supply without shunting
the ladder network. Resistance values will not be
the same in the two circuits because -the base is
at a higher voltage in the grounded collector
version.
The phase -shift oscillator produces its own input
by rotating the voltage vector at the output
through 180° by means of the ladder network.
Owing to the attenuation the rotated vector .is
much smaller in magnitude.
An interesting aspect of the grounded collector
version is that the small " rotated" output of the
network is added on top of the emitter voltage, so
that a resistance capacitance network is here being
used to provide a small step -up in voltage. It is
hardly necessary to add, however, that this
arrangement will never replace transformers.
Another type of circuit that appears in a
-continued on page 697
Tl
(b) pop- pnP
+ve
(c) Pop- nPn
www.americanradiohistory.com
692
The Meaning of Amateur
RECENT visits to Amateur
(Ham) radio stations have pro-
duced the surprising fact that a
large majority appear to be using
commercial equipment.
Surely the name " Amateur "
means literally amateur as
opposed to professional, yet a
greater and greater number seem
content to wear the amateur tag
yet use professional gear.
It would be interesting to know
why people do buy this very
expensive equipment as opposed
to rolling their own ". There are
ample circuits in handbooks and
magazines, and PRACTICAL WIRE-
LESS has produced quite a few
designs of its awn.
A. Heathfield, Harpenden,
Hertfordshire.
Good Old Octals
I HAVE read in PRACTICAL
WIRELESS over the past few
months, various people's views
on the use of octal -based valves
as opposed to B7G and B9A
based types.
I am surprised that none of
your correspondents has men-
tioned in his arguments one of
the great advantages of octal -
based valves, namely the fact that
they make much better contact
in their valve holders (providing
they are not paxolin) than do
B7G or B9A valves.
How many constructors can
say that they have never had
trouble arising from B7G and
B9A valves making poor contact
in their holders?
R. J. Lindsey. Whittlesey,
Peterborough.
Radio Servicing
[t WOULD like to thank, collec-
tively, all those readers who
wrote in on the subject of articles
dealing with servicing radio
receivers, following the letter
from Wm. G. Hall in the August
issue of PRACTICAL WIRELESS.
The response was quite surprising
and, apart from one solitary dis-
senter, unanimous in support of
the idea.
Accordingly, I am now arrang-
ing for a series of articles to be
prepared by specialist contribu-
tors, all with considerable pro-
fessional experience behind them,
and it is hoped to make an early
announcement on this special
series in the next issue. -- Editor]
NEWS AND.
ZENITH AM /FM RECEIVER
full quarter -wave telescoping f.m. aerial.
A socket is provided on the set for an external power supply which is
available at extra cost. Dimensions are 3.6ín. x 6.5in. x 1.9in. and the
price is £34 /6s. 3d.
United Mercantile Co. Ltd.,
distributors of Zenith radio
equipment announce the
Royal 810 personal -size f.m.¡
a.m. portable transistor
radio.
The Royal 810 has thirteen
tuned circuits, eight of these
on f.m. and five on a.m., a
broadband r. r. stage for
greater f.m. sensitivity, pre-
cision Vernier tuning and
PRACTICAL WIRELESS FILMSHOW
The date of Friday, 4th February, has been fixed for the "Practical
Wireless" and "Practical Television" Filmshow. Two films will
be shown. For further information, see next month's "Practical
Wireless ".
OSCILLOSCOPE FROM ADVANCE
The OSIS oscilloscope is aimed particularly at the educational field
and for general purpose use in industrial applications. It has been
designed for simplicity of operation and ease of servicing.
As the OSIS is most suited to educational needs, Advance are offering
it as a special price to educational establishments.
Servicing is simplified because only one type of valve is used through-
out and the majority of components are mounted on a single printed
circuit board.
The OS15 features a bright, clear display on a 5in. helical PDA tube,
the display area being 8cm x 10cm.
The total bandwidth of the vertical amplifier extends from d.c. to
3Mc /s with a sensitivity of IOOmV /cm and the timebase from Isec /cm
to 0.5,usec /cm, using switched and continuous controls. The latter
control (X gain) provides an expanded trace of up to two screen dia-
meters along the X axis. Any part of the expanded trace can be viewed
at the centre of the screen. Calibration accuracy is typically 5% in
both axes.
Triggering facilities are fully comprehensive from either internal or
external sources, including the triggering of the timebase from frame
pulses of a composite TV waveform (TV mode).
The 0515 is contained in a metal case, covered in a blue grained PVC.
Measuring I0 in. high x 81-in. wide x 16h-in. deep, the instrument
weighs I81lbs.
The ex -works price is £55, or £49 IOs. to educational establishments.
GPO RADIOTELEPHONES A SUCCESS
By the end of the first eleven weeks of operation of the London two -way
v.h.f. Radiophone System, some 255 motorists had placed firm orders
for installations.
The capacity for the system at present is about 350, although this
figure is subject to some revision. The "busy period" varies from week
to week but tends to be from 9 a.m. to I p.m., with the calls averaging
about 18 an hour.
www.americanradiohistory.com
..COMMENT
MARCONI EQUIP VOICE OF AMERICA
The photograph shows the
impressive main transmitting
hall of the "Voice of America"
relay station at Woofferton
in Shropshire, England. Six
of the largest Marconi high
power short wave sound
broadcasting transmitters are
now in operation providing a
total of 14 Megawatts o,
h.f. power.
This power is effectively
doubled by an advanced mod-
ulation techpique used on
each transmitter. This tech-
nique, which is known as trapezoidal modulation, is new in its application to
broadcast transmitters. It allows the signals to overcome heavy interference
and gives an intelligibility at the receiving end equivalent to a conventional
transmitter of more than double the power.
The transmitters, type B6122 radiate 250kW and are mounted three on
each side of the hall. They are housed in free standing cubicles which may
be moved, providing considerable flexibility in station layout. They can
operate in the frequency range from 5.95 to 26IMc /s.
HOME OFFICE ORDERS 600 MORE PACKSETS
Six hundred Packsets for use by British Police Forces and Fire
Services have been ordered by the Home Office from the
Telecommunications Division of Ultra Electronics Limited.
This is the third successive year in which Packsets have been
ordered in quantity by the Home Office. By the time that
deliveries have been completed, there will be more than 2,000
in Police and Fire Service use.
The Ultra 3A4 Packset, weighing less than 3lbs., forms part of
the "Vigilant" range of communications equipment. It operates
in communications bands up to 179Mc's, with provision for a
maximum of three channels. Battery life is up to eight hours
between charges, and the operational range is up to five miles.
MARCONI DOPPLER IN QUANTAS 707 AIRCRAFT
A major export order, worth approxi-
mately £A500,000, is announced for
Marconi Doppler Navigation systems
and airborne navigation computers to
be fitted in the entire Qantas Airways
fleet of Boeing 707 aircraft.
The photograph shows a Qantas
captain setting up a new track angle on
the display unit of the navigation com-
puter, installed in one of the Qantas
aircraft.
Track angle and distance -to -go can be
set up for two successive legs of a flight.
The position of the aircraft on the
appropriate leg Is then indicated by the "across track error" in nautical
miles to the left or right of the selected track, and by the distance remain-
ing to be flown along the track. This distance runs down automatically as
the flight progresses. In automatic operation, the computer changes onto the
next leg of a flight as the distance -to -go reaches zero.
693
Correspondents Wanted
I WOULD like to hear from
P.W. readers in Great Britain or
in any other country who are
owners of " Gramdeck "
recording equipment. I am 18
years old.
Henry Raymond.
Duchess of Kent Hospital,
Sandakan,
Sabah,
Malaysia.
I Am interested in communi-
cating with radio fans the world
over, especially the United King-
dom. I am a Detective Constable
and interested in radio experi-
menting.
David Jack. Caroni Police Station,
Trinidad, W.I.
I would like to correspond
with any SWL or constructor of
my own age, in any foreign
country. 1 am 16 years old and
very interested in transistor
circuits and SWL.
David Hendon. Copthorne,
Wix Hill. West Horsley,
Surrey.
T AM interested in short wave
listening and electronics in
general. I would like to corres-
pond with anyone who shares
these interests and who is of my
own age (12).
Malcolm Beet. 17 Firs Avenue,
Alfreton,
Derbyshire.
I WOULD like to correspond
with any radio servicemen from
any country as I am interested
in radio /TV service technology.
I will promptly answer any
letter received.
M. J. Solanki. P.O. Box 66,
Kitale,
Kenya Republic,
East Africa.
I WOULD like to tapespond
with anyone of my own age (15)
from any country, who shares the
interests of SWL and radio con-
struction of all kinds. I have a
Cossor 4 -track 3$ i.p.s. Maximum
spool size 5$ in.
Anthony Jones. 73 Newfield Drive,
Crewe,
Cheshire.
www.americanradiohistory.com
694 PRACTICAL WIRELESS December, 1965
TAPE RECORDER
Conversion to Four Tracks
THE four -track recorder, since its introduction
some years ago, has achieved a great
popula{ity, due to its economy, attained with-
(Mt any noticeable loss in performance compared
with corresponding two -track types. Probably
many others besides the writer considered the
possibility of converting their two -track machines
to four tracks. but one hesitates to begin what may
be extensive modifications to an expensive piece of
equipment if successful results are uncertain. The
writer approached the task with this attitude and
found it much simpler than expected. Perhaps
Others will be encouraged to follow.
The first difficulty was to obtain a good pair of
four -track heads, because, as the reader is no
doubt aware, two heads are used in the vast
majority of tape recorders (cheap battery imports
are an exception, but it is not worth while conver-
ting these). It is obviously preferable to employ
heads such as are used by the manufacturer in the
four -track version of the tape deck to be conver-
ted, but this may be impossible or too expensive.
The writer achieved satisfactory results on a
By A. J. McEvoy, B.Sc.
Collaro " Studio " deck using a surplus set of
heads available from Lasky's Radio at £2 19s. 6d.
Conversion can now begin.
If the manufacturer's heads are to be used, it is
likely that no changes to the mountings are
required; they will fit into the space vacated by the
old heads. However, some metalwork may be
necessary if heads of a different make or model
are to be used, but usually, as in the case of the
writer's machine, this will be limited to drilling
new bolt holes. The chief difficulty in mounting
the heads is to ensure proper positioning with res-
pect to the tape as it passes them, so that there will
be no "crosstalk " between right -going and left -
going tracks. To simplify this procedure it is
advantageous if the two new heads are mounted
on a common mounting plate, or can be mounted
on the plate used for the old heads.
The width of the tape is divided into four strips
for recording purposes, and the first and third
0.25"
1
3 \ \\\\\\\\ \\ \ \\\ \\\ \ \ \ \ o \ \ \ \ \ \ \
\\\
Fig. I: Specified spacing of 4 -track recording.
counting from the top must correspond with the
gaps in the heads. These gaps can be seen as fine
short lines on the faces of the heads. If, as was the
case with the heads used by the writer, both heads
are rigidly mounted on a plate by the manufac-
turer, this adjustment is made by setting the level
of the mounting plate; otherwise the heads must
be adjusted individually. The most convenient
way, if no proprietary mounting adjustment is
supplied on the recorder, is to obtain a number of
thin fibre washers and place these on the bolts
securing the mounting plate or the individual
heads to the deck of the machine until the top of
the gap on the erase head is level with the top of
the tape. The correct level will later be reached by
tightening the bolts and compressing the washers.
The heads must be mounted so that when the tape
is being rewound it is not in contact with the
heads, since rapid wear would result. For record-
ing or replaying the tape is brought into contact
with both heads by pressure pads linked to the
switching mechanism.
At this stage the new heads are connected to the
electrical circuitry of the recorder. The connec-
tions to the old heads are removed, after taking
careful note of where the wires lead. The new cir-
cuitry is shown in Fig. 3, a two -pole two -way
switch being used for track selection. The erase
head, which is easily identified by its wider gaps,
its lower impedance, and the fact that it is
mounted to the left of the record head in a pre -
mounted pair (so that, in operation, an old pro-
gramme is erased before a new one is recorded, as
the tape moves from left to right) is wired first.
Any thin insulated wire is satisfactory, such as
that used for earphones.
Of the four terminals appearing at the rear of
the head, those for the different tracks can easily
be distinguished by their grouping. One from each
track are joined directly to the erase signal source;
the other pair go to the switch, the slider of which
will then complete the erase circuit through one or
the other. The wiring for the recording head is
similar, but here lightweight screened cable must
be used and leads kept short in order to minimise
hum. The switch may be mounted at any conve-
nient place on the recorder; in this instance the
writer soldered it to the casing of the heads after
their final adjustment.
The recorder may now be switched on and
tested, preferably using a tape pre- recorded on a
commercial four -track machine; this will ensure
that the standard track positioning is attained. On
replay the material recorded on one track should
be audible, and moving the track switch should
bring in a different recording. If there is "cross-
talk " or mixing of the material on different tracks,
or the sound reproduced is totally unintelligible,
indicating that material recorded on one of the
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
262gn TAPE RECORDER
for ONLY £19.10.
care 12/6
Bargain of the Year Offer
-Cancelled Export Contract
Famous manufacturers brand new
unused and factory tested 2 speed.
31 and 711.p.s. twin track tape
recorder 3 Watt output. Tape
positron Rev.-counter, fast for-
ward and rew'nd. take 7' reels,
mike and gram input. Straight
through amplifier facilities. Out-
put sockets for ext. speaker.
monitor or external amplifier
Super -imposed switching magic
eye recording level and maim neon indi
cater. Volume and tone controls 7° x 4' 404
speaker. Attractively styled cabinet
with detachable lid mike and reel storage facilities,. A.C. 200/250 volts
operation. Complete with crystal mike. tape spare reel and amen lead etc.
L.P. RECORDING TAPE BARGAIN
By leading British manufscture.e-
PROFESSIONAL GRADE
DOUBLE -SIDED
teach side coated) 51" reels only
Special price offerw g7,2o, -
post free
Ideal for the experimenter who wants to
record both sides, and a good L.P. Tape
for the enthusiast who wishes to record
single side only.
OFFER!
SPECIAL OFFER 8' Message
tape 150', 8 /9; 3' L,P, 226'.
4/8; 3' D.P. 300', 6 /6. P. A
P. per reel fid.
TAPE REELS. Motee. surplus
7', 2/3; 5t'. 2 / -; 5'. 2 / -; 3'.
1/3; spool containers. 3', 118;
5 ". 1 /9; 51', 2/-; 7', 2/8.
Alums. Chassis. log. Plain Uodriled,
folded 4 sides, 2' deep, 6' z 4', 4/6;
8' z 6', 5/9; 10' z 7', 6 /9; 12' x 6',
7/6; 12' x 8 ", 8 / -, etc.
Alumin. Sheet, 18g. 6' z 6', 1/ -;
6' x 9'. 1/8; 6' x 12 ", 2/ -; 12' x 12',
416. etc.
Jack Plugs. Standard 21' Igranic
Type, 2/8, Screened Ditto, 8/8.
Miniature scr. 14', 2/8. Sub -min. 1 /3.
Soldering Irons. Maim 200/220V or
230/250V. Solon 25W Inst., 29/6.
Spare Elements, 5/8. Bits. 1/3.
65W, 29/6. etc.
6 VALVE AM -FM TUNER UNIT
Med. and VHF 190m -650m, 86
Me /a -103 Mds, 6 valves and metal
rectifier. Self -contained power unit.
A.C.200 /250V operation. Magic -eye
indicator, 3 push -button controls,
on/off. Med., VHF. Diodes and high
output Sockets with gam control.
Illuminated 2- colour penpes did
114'14', chassis size 11 °fá x 4' x 51'.
A recommended Fidelity Unit for use with Mallard "3.3" or "6.30" Ampli -
tiers. Now available as complete kit as illustrated, inn.
power unit. Carnage 7/6. L10.19.6
Ditto, but less power unit, 69.19.8,
Circuit and construction details, 4/8. free with kit. carriage 7 /6.
Condensers- S11ver Mica. All values
2pF to 1.000pF. 8d. each. Ditto
Ceramics 9d. Tub. 450V T.C.C. etc.
0.001 rond te. 0.01 and 0.1 /350V..
9d. 0.02.0.11500V., 1 / -. 0.25 Hints
1/8, 0.5 T.C.C. 1/9, etc., etc. Close
Tol. S /Micas -10 ;(, 5pF -500 pF 8d.
600- 5,000pF, II -. 1% 2pF- 100pF,
9d. 100pF- 500pF, 11d. 575pF,
5,000pF. 1 /6. Resistors -Full
Range 10 ohms -10 meg, ohms 70%
t and 4W, 3d., 1W. M. (Midget
type modern rating) 1W, Bd., 2W.
9d. Hi -Stab. 5% 3W, ;W. 6d. (100
ohms -I meg). Other values 9d.
1% ¢W. 1/8 etc., etc.
Volume Controls -6K -2 Meg. ohms.
3n-. Spindles. Morganite Midget
Type 1r /sin. diem. Guar. 1 year.
LOG or LIN. ratios less 8w. 8/ -.
DP. Sw. 4/8. Twin Stereo less Sw
7/8 100k to 2M ohms with DP Sw.
9/6.
WAVECHANGE SWITCHES. 1 p.
12 -way 2 p. 2 -way, 2 p. 6 -way.
3 p. 4 -way. 4 p. 2 -way, 4 p. 3 -way,
long spindle. 3/6 ea.
EXPANDED ANODISED METAL.
Attractive gilt finish tin. x t /sin.
diamond mesh 416 sq. ft. Multiples of
gin. cut. Max. size 4it. x 311., 47/6,
plus arr. Do., finer pattern most
4/8 sq. ft., multiples of 12in., max.
size 3 ft. x 2 ft., 27/8 sheet.
ENAMELLED COPPER WIRE -
31b. reels 14g -206, 8 / -; 22.-28g, 3 /8;
86g -38g, 4/9; 39g -40g, 5/-, eta
JASON FM TUNER UNITS.
Designer- approved kit of parte.
FMT1, 5 gus. 4 valves, 20 / -.
FMT2, £7.10.0. 5 valves, 86! -. JTV
MERCURY 10 goo. 3 valves. 2216
JTV2 £13.19.8. 4 valves, 28/8.
NEW JASON FM HANDBOOK, 2/8.
48 hr. Augiment Service 7/8.
['. & P. 2 /6.
TRIMS ' ' ;. eram e (Compression
Type ) -30pF, 50pF, 70p0', 9s..; 100pF/
150pF. 1 /8; 250pF, 1/8; 6000F, 1 /9.
PHILLIPS. Bee Hive Type (cons air -
spaced)- 2 -8pF, 1 / -; 3-30pF, 11 -.
KNOBS- Modern Continental types
Brown or Ivory with Gold Centre;
l' dia.. 9d. each: is /,', 1/- each;
Cone. knobs ivory with Gold Centre
1/' dia. 2/9 per pair. Matching ditto
2/6 ea
LARGE SELECTION AVAILABLE.
METAL RECTIFIERS, 8TC Types-
It MI, 418; 1111.2. 518; RM3, 7/8;
11.124, 16/ -; RMS, 21/ -; RM4B, 17/8.
TUB -ELECTROLYTICS -CAN
25/25v. 50/12v. 1/9; 8 +8 /950,. 9/6;
50/50..100/125v. 21- ;82 +32/275v. 4(8.
8/450v. 91350v. 2/3; 50!5013400.. 6/61
16-F18/950v. 5/8; 62/250/275,. 12/6;
32 + 32(450,. 6/8 ;100 +200 /275v. 12/6
695
NULLARD "3-3" á "5.10"
HI -FI AMPLIFIERS
3 ohm & 15 ohm output
3 -3" Amp. 2 valve, 3 watt 51.6
quality at reasonable cost. Baas Boost
and treble controls quality sectional
output transformer, 40 c /8-26 55 /5
6,.,,,,'"/ + 1 dB, 100mV for 3W. leas than 1%
distortion. Bronze escutcheon panel.
Complete Kit only 26.19.6. Carr. 51-A
Wired and tested 88.10.0.
BOLLARD "5-19 AMPLIFIER. 5 valves 10W 8
and 15 ohms output. Mullard'a famous circuit with
heavy duty ultra- linear quality output trandormer
Basic amplifier kit price £9.19.6 fir. and Ind 7/6.
Ready built 114 gas.
CONTROL PANEL KIT. Bass. Treble and Vow controls &position
switch tape
AMPLIFIER for T AND CONTROL PANEL KIT, 811.19.6. Ditto, retry wired.
£19.19,6.
2 -VALVE PRE -AMP. IINIT. Based on Mollard's famous 9 -valve (*KEYING
circuit with full equalisation. with volume, base, treble and 5- position selector
switch. Size 9 z B z 2 ;In. Ready Rollt 27.19.6, Carriage 3/8.
DE -LUXE
RECORD
PLAYER
KIT
Incorporating
4 Sp. Garr. rd
Auto -Slim unit and Mollard latest 3 watt
printed circuit amplifier (ECL 86 and
EZ 80), vol., bass and treble controls,
with 8' z 5' 10,000 line speaker.
Contemporary styled 2 -tone cabinet.
charcoal -;Crey and off -white with
matching blue -relief. Size 174' x 18' z
8'. A stylish unit capable of quality
reproduction- Circuit and coast. details
2/6 (free with kit). E, 1 3.19.6
COMPLETE KIT
Carr. and ins. 12/8 Ready wired 30 /-
extra.
ID ®lusted perspex control panel
escutcheon, 7/8 extra. Four contem-
porary mounting legs ói0, 10/6; UM.
1116; 12in. 12/13 xtr,
TRANSISTOR
COMPONENTS
Midget I.F.'e -485 Ke /e 9/181a.
diem. fleet, second or third..5/S
Ose.. Coll M. A L.W. 9 /16 III. din 6/.
Midget Driver Trans. 9:1 8/-
Midget Output Trans. Push-
Pull-3 ohms II-
11 mFd. -500 amid ee-LMISd, mPM.
2 / -, 12V,
Condensers 160 v. werldeg:
.01 mFd.. .02 mFd., .09 mFd-.
.04 mFd. 9s.; .06 mIed.,.1 mPd..1 / -;
.25 mFd., 1/3; .5 mFd., 1/6, etc.
Midget Tuning Condensers. J.B.
"OO" 208 pF and 176 pF. 8 /6.
ditto with trimmers, 9/0. J.B..
220 pP and 106 pF tuna slow
motion 10 /8. 366pF cingie 7 /6:
Sub. min. ;in. Deemin 100 PP,
300pF, 600pF, 7/- each.
FEREITE AERIALS, M. lk LW.
cat aerial coil 9/3.
Midget VoL Control with edge
control knob, 5 K /ohms, with
scotch 9/9; Ditto less switch 3 /9.
Speakers: P.M.; tin. Plessey 75
ohms 16/8. 251n. (7nntlnental 8
ohms, 18/6. 7 x 41n. Plessey 36
ohms, 38/6
Ear Plug Phones-La. Ost
tmenta) type aft lead, la* plug
and socket. High Imp- Si, Low
imp., 7/8.
Phono Plugs, 9d Phono Sockets (open)
d, Ditte (closed). 1/ -, Twin Phono
Sockets open/. 1 /8.
7 VALVE AM /FM RADIOGRAM CHASSIS
Valve line -110 ECC85, ECH131, EF89, New 1965 Model now available
EABCBO, 2184, EM81, EZ80.
Three Waveband and Switched Beam
positions.
c
Long
0-- 2,,000 mV HF FM 88 96 Mc
Phillips Continental Tuning Insert with
permeability tuning on FM and com-
bined AM /FM IF transformers. 400
Re/e. and 10.7 Mc /e. Dust core tuning
all rods. Latest circuitry including
AVC and Neg. Feedback. Three watt
output. Sensitivity and reproduction
of a very high standard. Chassis size
13;x etin. Height 7410, Edge illumin-
ated glaze dial 115 x 34in.
Vertical pointer. Horizontal station names. Gold on brown background.
A.C. 200/250v. operation. Magic-eye tuning. Circuit diagram now available.
Aligned and tested ready for use 518.19.6. Carr. A Ina. 716.
Comp. with Tape. O'P socket, ext. sp'k'r and P/U sockets and indoor F.M.
aerial and 4 knobs -walnut or ivory to choice. 30 F.M. Speaker only required.
Recommended Quality Speakers 10' Rola, 27/6. 134' a 8' E.M.L Fidelity, 57 /6.
12' R.A. with cone. Tweeter, 42/6. Carr. 2 /6.
BONDACOIIST Speaker Cabinet Aeomtie Wadding (1 in. thick appeau.) 19 :y
code, any length cut, 2/3 per ft., 8/- per yard. TINNED COPPER WIRE, 18496.
4/- 01h. ERSIN MULTICORE SOLDER. 60/40 9d. per yard. Carton. 8d..3./-, 2/8 eta
TYOAN FRET or Venir, 12 z 120,. 8l -; 12 z 181n. 8 / -; 12 x 24m.
We manufacture all types Radio Maine Trauet., Chokes, Quality 0/1' Trans.. etc
Enquiries Invited for Specials. Prototypes for small pmduotion rums,. Quotations
by return. Send for detailed bargain fist 3d. stamp.
RADIO COMPONENT SPECIALISTS
70 Brigstook Rd., Thornton Heath, Surrey. Have: 9 a.m. -6 p.m. 1 p.m.. Wed'
THO 2188. Terns C.W.O. or O.O.D. Post alud Pontiac fa 4 Its. l/. 1 1/S; 3 D.
8 / -; b lb. 3/9; 5 lb. 4/6.
www.americanradiohistory.com
696 PRACTICAL WIRELESS December, 1965
ADAMIN THERMAL STRIPPERS
FOR PTFE INSULATION
FOR PVC INSULATION
The new ADAMIN
thermal wire strippers
allow one -handed opera-
tion, using a simple twee-
zer action.
They strip coverings of
up to about 5/32 inch dia-
meter with absolutely no
risk of damaging the
conductors.
use Model 2B24, (illustrated), available
for 24 volts only.
and similar low temperature materials,
use Model 236, available for 12 or 24
volts.
LITESOLD TRANSFORMERS permit safe operation from any mains power point.
Free details of the whole wide range of ADAMIN and LITESOLD soldering equipment
In brochure SP 10.
LIGHT SOLDERING DEVELOPMENTS LTD., 28 Sydenham Road, Croydon,
Surrey. Telephone: CRO 8589
STEREO
AMPLIFIER ASSEMBLY
F.M. TUNER
KITS WITH A FUTURE
The Martin Audiokit assembly you own today can
become part of an even better hi -fi system tomorrow.
No other system allows you to enlarge your
installation stage by stage in the way Audiokits do.
They comprise a wide range of very well made
prefabricated units in which the connections are
standardised throughout. Each is rigorously tested to stated
specification before despatch. NEW KITS FOR
ADDING ON ARE IN COURSE OF PREPARATION
NOW -so by starting with Martin today, you insure
yourself for still better listening tomorrow.
Choose Martin for quality
Build for 3 or IS ohm system
Start with Mono and add Stereo or start
completely with Stereo
Power packs available
Professionally styled escutcheon plates
Assembly is easy by following the well
presented instructions
S Pr5
stage Input Selector E2.7.6 10 watt amp. (3 ohms) E5.12.6
e -amp. and vol. control EI.17.6 10 watt amp. (15 ohms) (6.12.6
Pre -amp. with tone controls 03.2.6 Mains power supply 02.15.0
Send for leaflet describing entire range
mRRTin Martin Audiokits and Recordakits
are obtainable from good stockists
everywhere. In coses of difficulty
please write direct.
MARTIN ELECTRONICS LTD., 154/155 HIGH ST., BRENTFORD, M'SEX
Phone: 1SLeworth 1161 ; 2
MARTIN ELECTRONICS LTD. 1S4 -155 High Street I
Brentford Middlesex I
Full details of Martin Audiokits please
NAME - - - - - -- - -_
ADDRESS
(Block letters) - Pw12 I
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 697
alternate pair of tracks is being picked up, it
follows that the preliminary setting of the heads
described above was insufficiently accurate, and
should be re- examined. Otherwise, the proper
setting can now be found by tightening the mount-
ing bolts until maximum volume is achieved. If
the heads are fixed by the manufacturer to the
mounting plate,. both heads will now be correct;
otherwise the erase head must be adjusted for opti-
mum performance in a similar manner. Since its
gaps are longer, adjustment is less critical, but care
must be taken lest adjacent tracks be partially
erased when it is operating.
This completes the mechanical aspects of the
conversion.
The amplifier of the recorder will have been
designed with a frequency response such as would
correct reproduction to C.C.I.R. standards using
the old heads; there will therefore be some dis-
crepancy when the new heads are in use. However,
it is not likely to be worth the constructor's time
to attempt to change the time constants in the
correction network; to calculate the changes would
require more details of both heads and amplifier
than are likely to be available and the effects of
experimental changes are barely noticeable. The
tone control easily compensates for the new con-
ditions. The enthusiast may, however, wish to
obtain a little more gain, since the signal picked up
by the smaller quarter -width gap might not load
the amplifier fully. Fig. 2 shows a circuit found
suitable by the writer.
Operation is fairly straightforward. The
transistor used in a common emitter configuration
must be an n -p -n type, since the collector is to be
positive with respect to the emitter. The valve to
which the modification is to be applied is any of
the low -level amplifiers in the early stages where
the signal is still small and the current in the valve
low. The writer applied it to half of an ECC83
double triode which was biased to draw 0.5mA,
a very suitable current for the transistor in series.
The constructor must remember points like these
if he wishes to apply this circuit to other types of
valves.
C2 is the by -pass capacitor already in use with
the valve. It now acts also as a smoother to
supply the transistor circuit with an even d.c. The
output of the transistor appears across R2 and is
Fig. 2: The Pre -amplifier
circuit used by the author to
obtain extra gain from low
input signals.
--f
j_tesclaL
Replay
Slide
switch
Erase
Fig. 3: Wiring of the track selection switch.
direct coupled to the grid of the valve. R2 also
provides the grid bias of the valve, while R1
provides base bias for Trl. The usual potentio-
meter biasing system is not required to maintain
thermal stability, since the valve limits the current;
if the current in Trl were to increase due to
thermal effects the potential across R2 would also
increase; as a result the grid of the valve becomes
more negative with respect to the cathode,
decreasing the current passed.
All other systems in the tape recorder remain
unchanged. Modification to the four -track system
is not therefore such an expensive, difficult or
time- consuming task as the writer at first feared
and the cost will soon be reclaimed in increased
utilisation of his tapes. He is sure others will have
the same success.
CIRCUIT DISGUISES -continued from page 691
number of variations is the compound emitter
follower (Fig. 3) which uses negative feedback
from a second transistor to lower the output
impedance and raise the input impedance. The
arrangement of Fig. 3b is applicable with either
valves or transistors but that of Fig. 3c uses a
conjunction of p-n -p and n -p-n transistors and
there is no corresponding circuit with valves.
There is no fundamental difference between the
action in a circuit of n -p -n and p -n -p transistors.
The phase relationships are the same and it is
merely a question of d.c. polarities and consequent
suitability for direct interconnection.
It should be noted therefore that n -p -n and p -n -p
transistors in Fig. 3c can be interchanged if the
negative and positive supply lines are interchanged
at the same time. This literally turns the circuit
upside down.
By inserting a resistor in the collector circuit of
the second transistor it is possible to obtain some
amplification without phase reversal and this
arrangement can be used successfully in a Wien
bridge oscillator.
www.americanradiohistory.com
698 PRACTICAL WIRELESS December, 1965
TAPE
TAPE
TAPE TERMINOLOGY
TAPE
PART FIVE
SPOOL
Reel on which the tape is wound. Although not
completely standardised, spool diameters fall
within fairly well defined limits: for portables
3M. to 3 1in., for domestic machines, table models,
Sin., S }in., 7in., and for professional models 8 }in.
and the N.A.B. standard 10 }in.
Spool shapes vary greatly with various patented
hub -locking and tape -fixing methods (see also
Hub -Lock).
SPOOL DRIVE
Method of tape drive which dispenses with
capstan and pinch roller and depends on winding
action of take -up spool. Disadvantage is that the
speed varies with the diameter of the winding
spool, i.e. the amount of tape wound on. This
prevents the interchange of tapes between
machines.
STANDARDS
See also Equalisation. Standards relate to
equalisation of record and replay response to
allow for non -linear characteristics of the medium.
The European standard is laid down by the
Comite Consultatif International Radio (CCIR)
and the American standard by the National
Association of Radio and Television Broadcasters
(NARTB or NAB).
The aim is to provide a guide for machines and
tapes whereby any tape made on any machine can
be replayed on any other machine with no loss
of quality which would occur by an alteration
of the frequency response curve.
This curve is obtained by calculating the output
voltage from an assumed perfect head with an
infinitely narrow gap over the expected range (If
frequencies.
If the output thus derived is fed into a time -
constant combination of capacitor and resistance
-at one particular frequency the impedance of
the capacitor will equal the resistance -and the
straight -line graph of the loss -free head plotted
to intersect the measured curve, an asymptote can
be drawn to intersect the curve 3dB down to give
a " turnover frequency".
This gives us the recording characteristic and a
replay chain has to be designed to compensate for
the slope of the curve and produce an output
which is a replica of the original sound.
The standard can be defined by the time -
constant of the combination: thus for a speed of
7 #in. /sea the original standard was 100psec with
by H. W. Hellyer
a turnover frequency of 1.6kc /s. With improve-
ments in record /playback heads and materials it
has been possible to revise standards and these
have a shorter time- constant.
At 7 }in. /sec. the 70psec standard is now used
and for 3 }in. /sec. the standard has been reduced
from 200 to 140psec. The turnover frequency is
related to the time- constant in the following way:
Ft =160CR where Ft is the turnover frequency
in kilocycles and CR is the time -constant in micro-
seconds.
In practice there is a 6dB -per- octave rise in the
curve from a playback head reproducing the
signal of a constant recording, as in Fig. 17a,
which requires an amplifier with a response as in
Fig. 17b to obtain an output reasonably flat up
to and beyond the turnover frequency as in
Fig. 17e.
This is done in several ways, a typical feedback
circuit with selected component changes for
different speeds being illustrated, Fig. 18. For
example, at 3 }in. /sec. CR =1.2M x 180pf= 216psec
with a turnover frequency a little above 800c/s.
STACKED HEADS
Two or more gapped heads with gaps disposed
vertically one above the other. Used for stereo
recording and replay.
STEREO RECORD AND PLAY
Two- channel method using two separate ampli-
fiers and either a stacked half -track head or the
two tracks of a quarter -track head. A four -track
machine can be adapted for stereo replay by the
addition of a separate amplifier channel but
recording needs the provision of a bias and erase
oscillator also for the second track.
Stereo records are made in quarter or half
track. Replay of half -track stereo on four -track
machines is not effective owing to track spacing
-(see Tracks) -although half -track mono record-
ings are usually able to be replayed quite well.
STOP FOIL
Strip of metallised tape spliced as leader or
interval section in a tape for use as automatic stop
or tape reversal contact.
STORAGE
Tape should be stored in conditions of even
temperature and humidity and not spooled too
tightly. In conditions of high temperature and low
humidity tape becomes brittle. When again
subjected to normal humidity the tape will tend to
www.americanradiohistory.com
December, 1965
Sheet
Paxol i n
Ideal for tran-
sistor projector
Special offer
12 panels 6 x 81n. 5/ -.
Bargain of the Year
A complete kit
of parts to build
6 transistor/
2 wave
superhet
receiver
at only
3916.
Post
and
Ins. 316.
PRACTICAL WIRELESS
"CORONET" Mk. IV
It fully covers the medium waveband and
that part of the long waveband to bring in
B.B.C. Light. The circuit Includes a highly
efficient slab aerial and 25th. P.M. speaker.
Overall size approximately 44 z 25 x Ills.
Supplied complete with carrying case and
instructions.
MAINS POWER PACK
Designed to operate transistor sets and
amplifiers Adjustable output fiv -9 to 12
volts for up to 500mA (class B working).
Takes the place of any of the following
batteries: PP1- PP3- PP4- PP6- PP7 -PP9 and
others. Kit comprises: mains transformer-
rectifier, smoothing and load resistor, 5000
and 500 mid condensers. zener diode and
Instructions. Real snip at only 14/8 plus
8/- post.
This Months' new Bargains
Indicating Unit Type ME. This is in a metal
case size 85 x 8 x 9 approx. The front panel
has magic eye, two "adjust" controlo and
on /off switch and there is an open space size
approx. 65 a 4 in which a panolis panel could
be fitted. Internally there to a complete Maine
Power Pack on a separate panel, the trans-
former is for 230/240 main input, it gives
350.0 -350 H.T. 6.3 a 5v L.T. The Power
Pack is complete with 5.4 rectifier, choke and
smoothing condensers:-in addition there is
a magic eye and 4 E.F. 60 valves with all
ancillary components. We don't know what
the unit was originally intended tor, but it
could very easily be turned into a valve
Voltmeter, Capacity bridge, electronic
megometer, etc., etc., at 27/6 plus 7/6 post,
which is less than the price of the trans-
former alone.
Orsm or Tape Motor. Made by Garrard for
their best Changers, each one "LAB" bal-
anced. Offered size 21 x 3 x 2, regret only 110v
available. Offered at 12/6 plus 2/9 poet.
Beethoven Coil Pack. Covers medium wave
and two shorts (regret exact coverage not
known) uses 6 coils, 6 trimmers and 4 pole
wave change switch and it's aligned ready for
use. 7/8 plus 2/6 post.
Wall Mounting Thermostat.' By Satchwell
intended for use to control tubular or any
type of space heaters indoors or in a green.
house- Adjustable over 40 /80 deg. Complete
with mounting screws 29/8. plus post 2/9
(normal price re at least twice this).
Morganite Sealed Pots, Another batch of
these has arrived and we can now offer quite
a range namely: 5K, 50K, 100K. 250K,
{ meg, 1 meg, 2 meg, all at 6/- per dozen per
value, plus 2/9 poet on first dozen, then 1/-
per dozen. Less than one dozen price is 94
each, even this is only about one -tenth of the
catalogue price and this is undoubtedly one
of the bent pots available.
Tuning Condensers. 2 gang .0005 mFd air
spaced standard size with good length
spindle 30/- doz. or 3/9 each, post 2/9 up to
sin, 3/0 per dozen.
Toning Condenser. Bakelite type .0005 mFd
for tuning or reaction, inch eplindle 25 /-
per doz. or 3/- each, post 2/9 per doz.
OZONE OUTFIT -for removing smells
and generally hnproving any oppressive.
at mosphcre. Kit consists of Philips
Ozone Lamp and mains unit, only needs
box. 19/8 plus 3/6 postage and insurance.
Where postage is not definitely stated man
extra then orders over 83 are poet free.
Below 68 add 2/9.
CIRCLE -LITE
Brings sunshine into your
home. 150 watts of light
but soez only 40 watts..
Beautif ul fittings with
glass, not plastic centre,
fluorescent tube and
choke control. Made by
Philips. Will give a
lifetime of service.
C ç Regular price 24.15.0.
65
Special Bargain pries / plue 8/6 carriage and insurance.
Please state colour of glass centre white, pink, blue, red, black, yellow
or cream. Also whether plug into lamp holder or ceiling. mounting
model 80 watt model 99/6.
AIRCRAFT
RADIO
RECEIVER
Type CW 0480 48 D
This is part of the equip-
ment RU19, American
made equipment for the
Navy. It o a 5 -valve
receiver with a really
beautiful precision tun-
ing mechanism. Brand
new and In original
packing but less coil
units. Limited quantity
only. 19 /8 pius 3/6 P. er P.
THIS MONTH'S SN
eine"'"-e% CAPSTAN DRIVER
Tape Recorder
Although some well made
spool driven machines give
remarkably good result.
there hi no doubt that
to achieve anything like
perfection and to have
versatility a Capstan Driven
Tape is essential. Now at last
we can offer you a Capotan
Driven, completely portable,
battery operated instrument at
a remarkably low price. So low in tact that you can easily afford to
have a second machine for use in your car, office. home etc. or to give
to reps or relations to exchange tapes.
SPECIFICATION: -200/7000 C.P.B. -400 MW output- doable
track -twin speed Iii and 741 cast rewind time --IV spool gives one
hour playing with standard tape weight 7 lbs. Size 8 x 11 a 55.
Complete with batteries, microphone -tape spool and instruction
manual. Nothing to go wrong if you use good tape and keep
heads clean. Demonstration gladly given at One Croydon shop.
special Snip Price This Month. £11.11.0. Post & Insurance 601.
TWO -WAVE BAND 7 TRANSISTOR
POCKET RADIO
Is a One medium a long wave euperhet traoolator complete with
carrying handle earphone and battery. A very good little set that will
get all the "Pirates" and which will make an ideal present for child
or adult. Very recently advertised at 65. Offered to you at 63.19.8 plus
3/6 post and insurance. Two or more post free.
699
SNIPERSCOPE
¡/ 1NFIIA-RE0
S(NSITIVC LA
FLUOIIESCENT
6COEEY
Famous wart me
cat's eye rued
for seeing in the
dark. This is an
infra -red image
converter cell
with a silver caes-
ium screen which
lights up (like a
cathode ray tube) `-
when electrons T
released by the infra -red strike it. It follows
that as light from an ordinary lamp is rich
in infra -red these cells will work burglar
alarms, counting circuits, smoke detectors
and the hundred and one other devisee es
will the simpler type of photo cell. Here
then is golden opportunity for some
interesting experiments. price 6/- each. Post
3 /.. Data will be supplied with cells if re-
quested.
Speaker Bargain
121a High -
fidelity loud-
speaker.
Highflnx
magnet type
with either
S ohm or 15
ohm speech
coil. Will
handle up to 10 watts Rand new by fsmoas
maker. Price 29/6 + 3/6 post and insomnia.
SPOT OR FOG
LAMP
Made by Luce, Flat a pencil
beam. 36 watt Suitable for car.
boat, caravan. etc. Complete
with 6 or 12v bulb, flex, cables
and fixing bolt. Remarkable
bargain. Price 12/6 4- P. a P. 318.
SELF
ENERGISED
TELEPHONES
These require no 'eel,.
terieo: In fact they
have only to be con-
nected by pair of
wires. They can thus
be fitted into existing
bell circuits. Rennie
are extremely good
and maintenance
I coots are nothing.
Handset. only 15/-
each. poet eta 3/6. Two, post free.
THERMOSTATS
Type 'A' 16 amp for coaecollinv room hostess,
greenhouse. airing cupboard. Has spindle One
pointer knob quickly adjustable from W-
80°F. 9/6 plus 1/- post. Suitable box for well
mounting. 6/ -. P. a P. 1 / -.
Type 'B' 15 amp. This Is 17ta. long rod
type made by the famous Bonnie
Co. Spindle adjusts We from 90-
550°F. Internal screw alters the
INFRA RED HEATER
Make up one of these latest
type heaters, ideal for bath-
room, kitchen, bedroom. etc-
They are simple to make from
our easy to follow instructions -nee Mlles enclosed elements designed
for the correct infra -red wavelength (3 microns). Price for 750 watt
element and metal casing as illustrated, 19/6 plus 2/6 post and hunr-
ance. Pull switch 3/- extra.
AUTOCHANGER BARGAIN
Garrard Auto Record
Player Model A.T.5
This le undoubtedly the
finest Auto changer made
in f cat its large heavy.
nonagnetic. die cast
Wroteb,e and biaa com-
pensated constant pressure
tybne together with its
laboratory series motor with
balanced rotor make It almost
a transcription unit. Other
special A.T.5 features arc:- Will take 8 records which may be
mixed sizes- stylus presume adjustable -may be stopped whilst
playing a record without rejecting rune record -fitted with latest
pick -rap for playing stereo or mono record,.
OFFER ED AT THE AMAZING PRICE OF 18.15.0 plus 6/6
Carriage and insurance.
MENINE WINDOIM
setting so Mk could be a:Wettable
over 30° to 1,000 °F. Suitable for
controlling furnace, oven kiln.
Immersion heater or to make 6ameetat or
Ore alarm. 8/8 phis 2)9 post and ineoranes.
Type "0" le a small porcelain thermostat se
fitted to electric blankets, etc. 1
setting adjustable by acre. through sida888..
P. a P. dd.
Type "D" We can this the Iee -etat se R cote
in and out at around freezing point. 2/6 amp..
Has many wee, one of which would be to
keep the loft pipes from freezing V length
of our blanket wire (16 yds. 10 / -) is wound
round the pipes, 7/0. P. a P. 111.
Type "E" This is a standard refrigerator
thermostat. Spindle adjustments cover normal
refrigerator temperature. 7/8, plus 11- poet
9 -Way push- button switch
Each way having two single pole change over
and one shorting switch, good length push
rods 30/- per doz. 8/6 each post 2/9 per doz
Waterproof Heater Wir
17 ;de. length 70 watts, self regeelatlag
temperature control. 10/ -, post free.
ELECTRONICS (CROYDON) LTD
Dept. P.W. 266 LONDON ROAD WEST CROYDON, SURREY
Post orders to: 4 Springfield Road, Eastbourne, Sussex
www.americanradiohistory.com
700 PRACTICAL WIRELESS December, 1965
R.S.T. VALVE MAIL ORDER CO.
211a STREATHAM ROAD, MITCHAM, SURREY
Mon -Sat. 9 a.m.
-5.45 p.m.
Wednesday I p.m.
Open Daily to Callers
Tel. MPTcham 6202
0A2 5/8
003 5/-
1A7 7/9
11)5 8/-
111.5 7/6
11.05 6/.
114501 8/-
1115 5/-
165 e/
1T4 2/6
sea 3/8
3Q4 6/6
3Q:, 818
384 4/9
3V4 e/-
07411 8/.
5U4G 4/-
6V40 8/-
5Y30T 4/6
52407 8/.
6/301.2 18/-
6.6.7 15/.
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SAMS 4/6
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OARS 2/8
BANG 2/9
6.40
6 Rqé
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6AÚ0 8/-
6280
6Be6 4 /9--
68115 419
esie6 éié
624121 7/8
61117 10/6
65E8 7/6
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1.28 %7 2/9
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1487 20/-
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37 5/.
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16004 1216
801 5/-
897
866 10j
964 4/-
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4022.411 6/-
6763 102
7193 1/8
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ATP4 119
ATP5 7/-
AT?? 4/6
AU2 M-
AUS 6/-
2,21 9/5
AZ31 7/9
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CE50'1 5/-
01.33 12/6
CY31 10/-
DAC32 7/6
DAF91 3/3
DAF96 6/-
DC090 7/-
DP3:3 5/-
D770 6/-
D791 2/8
DP92 8/8
DF96 6/-
D1177 8/6
DE31 7/9
DE81 5/-
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DUO 7/-
DLbI 4/9
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D270 6/.
01711 7/-
DY87 7/9
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7B041 4/6 7E184 6/6
ESC20 3/6 E131 3/-
7E780 5/- 71.33 17/6
EEF83 7/3 EL34 9/6
EBF89 5/9 E141 7/8
811L1 17/6 71A2 7/6
EB1.1110/5 71.84 4/6
7Cti'40 -/. ß190 61-
E0081 3/3 EL95 8/-
ßtx.v? 5/- 711:34 9/-
70063 4/6 EM80 e/-
E0084 5/6 7281 -/-
80085 5/9 E294 é/.
E0088 8/9 781715027/8
70980 8/6 14Y51
EC782 6/- 7186 6/3
E0221 19/. 2E36 4/9
E01133 13/- E240 6/6
ßCII4'1 BF EEO 6/-
E01181. 5/5 EZ80 5/6
ECH83 6/6 7281 3/6
E0190 6/- G230 9/6
ECL82 6/6 0239 9/-
EC1.83 9/. GZ34 9/9
Eel.86 8/6 7138 28/6
E79 90/- KT61 17/6
E736 3/- ET66 12/-
EF37A 9/6 ET81 10/-
E5'39 5/- ET88 m/-
E741 6/6 ETW61 4/3
E760 2/- ET241 8/.
7780 4/5 2L4 17/6
7E85 4/6 161.8 12/6
2786 6/6 2574 12/8
EF89 4/- 2014 4/-
7791 2/9 2140 12/8
7792 2/6 1137 10/-
178 15/-
N108 16/-
NOTI 8/-
NGT7 25/-
0'L4 4/.
PC86 10/-
PC89 0/5
PC97 7/-
7(,`C84 5/4
PCC89 9/8
700189 10/-
PCF'90 6/6
PCF8" 6/-
P(:F84 8/.
70786 8/6
PCF901 9/9
P0F80^ 9/9
PCF805 10/6
P07806 12/-
PCB808124
7C1.81 6/6
P0193 8/-
PC1A4 7/.
PCLSS 7/4
701.86 8/9
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72724 80/.
PRN45 8/-
FPN46 2/9
PL36 9/6
PL81 7/.
71.82 5/-
PL83 6/-
PL94 6/8
PL600 14/6
P%4 18/6
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PY8800 5/9
PY801 6/3
R9 4/-
719 7/-
R05/500 59/-
8130 10/-
8741 1/6
8761 1/-
8U'15 1B/6
817l15012/5
TDD4 7%-
TH41 20/-
U10 7/-
U14 7-
019 30%.
6726 10/.
1.726 10/.
U78 3/6
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0301 15/.
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0.4134780 5/8
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UC1,69 3/9
0E41 7/-
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01.41 6/9
LTL84 5/4
06180 7/-
UU6 18/6
171.77 10/8
11879 5/-
L'Y21 7/4
UY41 4/6
L`Y8,6 4/0
101197 27/0
VCR517B 30/-
VCR617C 80/-
V2P4G 17/-
VR105/306/-
V11150/306/-
VT73 12/6
VT31 90/-
17.7111 6/.
P17120 101-
V17508 26/.
W812 51-
%78 28/6
170 89/-
181-5 9/.
%P1-5 5/-
T5É 117 6
3801 4á//-
31,77 18/6
5(:71 80/-
CV1596 40/.
.4Ca10 94.e-0
SPECIAL 24 HOUR SERVICE
OBSOLETE TYPES A SPECIALITY
QUOTATIONS FOR ANY VALVE NOT LISTED Order Service
Postage 6d. per Valve. C.W.O. No C.O.D.
SETS OF VALVES
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THE
PEMBRIDGE
COLLEGE
OF ELECTRONICS
PROVIDES TRAINING
IN RADIO
AND TELEVISION
FULL-TIME COLLEGE COURSE
IN RADIO AND TELEVISION
Our Course has now been extended to sixteen months'
duration to include theoretical and practical instruction
on transistor television receivers, U.H.F. television re-
ceivers and colour television.
Next course commences 5th January, 1966.
This Course is recognised by the Radio Trades
Examination Board (R.T.E.B.) for the Radio and
Television Servicing Certificate examinations.
Provides excellent practical experience on valve
and transistor radio receivers and all well -known
makes of television receivers.
To:
The Pembridge College of Electronics (Dept. PII)
34a Hereford Road, London, W.2.
Please send, without obligation, details of Doe
Full-time Course in Radio and Television.
Name
Address
www.americanradiohistory.com
December, 1965 PRACTICAL
expand and, if spooled too tightly, the expansion
will be uneven. Care should be taken to avoid
magnetic fields and to stack spools so that
constant uneven pressure cannot warp them.
Storage in sealed metal cans is recommended
for long periods of disuse. When replaying, first
respool loosely to relieve any tensions that may
have been set up during long storage.
STRAIGHT -THROUGH AMPLIFIER
Tape amplifier with equalising circuits switched
out and signal applied to normal output stage for
use as normal, level -response amplifier.
SUPER -IMPOSITION
Method of recording a new signal on an existing
one by removing the erasing power or removing
the tape from the erase head while recording.
When the first method is used it is necessary to
modify the oscillator circuit to allow for the
absent erase head loading and still maintain bias.
In practice, matching of signal levels is quite
difficult and this system has been largely super-
seded by multiplay techniques. In conjunction
with fade erase and variable bias it can be effec-
tive as a means of recording commentary over
background music when producing tapes for ciné
work.
SYNCHRONISING
Method of ensuring that the tape is kept in step
with film or slide projector for sound commentary,
background, etc.
Two principal methods are used for cine film
projectors; (a) stroboscopic disc driven by tape and
illuminated by projector lamp. Projector speed
adjusted for stationary stroboscope pattern; (b)
synchronising pulses recorded on tape to control
projector speed. Recording is made on spare track,
or on special "pilot tone" narrow track while the
film is being made and on replay the pulse is used
to control speed of the projector.
Variations in speed of tape recorder cannot be
tolerated as much as slight variations in projector
speed, hence the method of allowing the recorder
to control the projector and not vice versa. A
direct method is the looping of tape over the
spindle of a synchronising unit which electrically
controls the projector speed. Synchronising units
are available separately.
A professional method is the use of sprocketed
magnetic tape on a special machine with speed
WIRELESS '701
control provision.
Slide projectors can be operated by solenoid and
relay actuated by pulses recorded on tape, or metal
foil strips.
TAKE -UP SPOOL
The spool on to which the tape is wound after
passing the head system.
TAPE
The medium on which signals are recorded.
Formed by a magnetic coating bonded to a flexible
backing. Coating in general use is iron oxide.
Width of tape is standardised (BSS 1568) at
0.246 ± 0.022in. Narrower tapes are now being
used in casettes and for other special purposes;
wider tapes are commonly used for multitrack
recording, video recording and computer work.
Coating thickness of standard tape is about 0.45
thousandths of an inch on a base of approximately
1.5 thousandths of an inch thick. Long Play tape
has a base of 1 thou., and a coating of 0.4-
0.5 thou. Double Play tape has a base half as thick
as this, and Triple Play also uses a 0S thou. base
but a reduced coating, to 0.2 thou. Recent develop-
ments have led to one company marketing a quad-
ruple play tape, with even less overall thickness.
Relative lengths per spool size and playing times
are shown in Table 1.
In general, tape with a thinner coating is less
sensitive, but has a better high frequency response
and requires less bias.
Base materials (originally paper) have differing
properties, making them suitable for particular
applications. Cellulose -acetate, used for standard
tape, tears easily, tends to absorb moisture, and
becomes brittle as it ages, but is relatively cheap.
Polyvinyl -Chloride (PVC), tape is stronger, flexible
and does not absorb moisture so readily. It tends
to stretch, but can be pre -stressed during manufac-
ture. Polyester tape is tough and does not stretch.
It has good temperature and humidity character-
istics. Although very suitable for thinner tapes, its
stiffness makes it more difficult to handle as a
standard thickness.
The adhesive used to hold the coating to the
backing is known as the " tape binder ". Its
chemical properties are generally closely guarded
secrets. A brittle binder makes the coating chip as
the tape flexes. A binder with a tendency to
become sticky at high temperature causes high
frequency flutter through tape sticking at guides
(TABLE I)
Reel
Size
(ins.) Std.
Tape length
LP.
(feet, in.)
DP. TP.
Playing
at 31 in.
Std.
time
/sec. LP.
(Mins, secs.)
(Single- track)
DP. TP.
3 ISO 250 300 450 8m. 13.20 16m. 24m.
31 175 250 400 600 9.20 13.20 21.20 32m.
4 300 450 600 900 16m. 24m. 32m. 48m.
4; -- 600 900 1200 - 32m. 48m. 64m.
5 600 900 1200 1800 32m. 48m. 64m. 96m.
5; 850 1200 1800 2400 45.20 64m. 96m. 120.8
7 1200 1800 2400 3600 64m. 96m. 120.8 180.12
8+ 1800 I 2400 3600 - 96m. 120.8 I 180.12 -
www.americanradiohistory.com
702 PRACTICAL WIRELESS December, 1965
and heads. A stiff binder tends to make the tape
curl with age and temperature change. Binders
usually contain lubricants and preservatives, but
additional tape lubricants are now available.
TAPE CLEANSER
In addition to the lubricants previously
mentioned, some liquid cleansers are available for
application to fixed felt pads (also referred to as
tape cleaners), over which the moving tape passes.
TAPE GUIDE
Flanged or grooved pillars or pins of non-
magnetic material, positioned to guide the tape
into its correct path past the heads.
TAPE POSITION INDICATOR
Device used to assist in finding required place
on tape without using any form of marking.
Simplest form consists of graduated 'scale marked
on top -plate, amount of tape on spool providing
edge for taking reading. Alternative method con-
sisted of feeler arm which touched outer winding
of spooled tape, and pivoted inner end registered
on a scale.
Later types use clock or digital scales, driven
from either spool, capstan or separate idler.' Spool
driven types are not entirely accurate as outer
turns have greater diameter than inner turns, but
revolutions are the same. Linear scale and greater
accuracy is obtained by a capstan drive or capstan
driven idler.
Many spools are themselves marked to indicate
footage, but accuracy of reading depends on tight-
ness of respooling, which can vary greatly.
TAPE PRE -AMPLIFIER
Special type of pre -amplifier, incorporating
equalisation circuits, and, if used also for record-
ing, pre -emphasis and perhaps bias oscillator
circuitry. (See also pre-amplifier.)
TAPE RECORD
(See also Pre -Recorded Tape.) Used to denote a
commercial recording, as a parallel to Disc Record.
TAPE SPEED
See " Speed ".
TAPE STROBE
Stroboscopic device used to indicate speed
directly by looping tape over pulley on which a
strobe disc is mounted, the disc markings being
calibrated, or otherwise tabulated, in inches per
second or centimetres per second. (The latter types
may be intended for use under lighting of a 60c /s
frequency, as may some USA types marked in in/
sec.)
TELEPHONE PICKUP
Induction coil system used near telephone
receiver to pick up and record telephoned
messages.
TEST TAPE
Pre -recorded tape to certain defined standards
used for testing the playback channel of a tape
recorder. Usually, in addition to the specified
standard characteristics, a test tape will have indi-
cated levels, and various frequency bands. White
noise test tape, containing frequencies throughout
the whole audio spectrum, at equal amplitude, is
used for certain system tests.
THERMAL NOISE
The characteristic hiss of white noise may also
be an indication of thermal noise caused by
current flowing through a resistance, or noise
generated within a valve because of the electron
stream. Low -noise valves have been specially
developed to reduce these effects, and changing
carbon compound to carbon deposited, wirewound
or metal-oxide resistors in current carrying circuits
can also reduce the annoying effect.
TIME CONTROL
Switch used to start and /or stop a tape recorder
automatically at a given moment. Used widely
with sleep- recording systems, and can consist of a
simple time- switch linked to the supply, or a more
sophisticated device which completely neutralises
the mechanical and electrical parts of the machine.
(To be continued)
On the Short Waves- contInued from page 683
CR7, CX8( Uruguay), ET3, KP4, KV4, LU3, PY4,
TN8 (Congo), TU2, VE3, VS9, YVS, ZS6, 3A2,
5A1, 5H3, 5X5, 5Z4, 9G1, 9J2, 9Q5.
A. H. 'Dickey (Bristol), R208 plus pre -selector,
75ft long wire, is our sole reporter for 28Mc /s:
CT1ON, DM2BBD, DL7GX, F2PY, UP2ADZ.
News and Notes
Top band looks promising for the winter trans -
Atlantic tests. 1SWL /9941 reports W1BB /1
coming in at 579. D. Mortimer says Gus Browning
was due to commence radiating from OY land at
the time of writing. Anyone hear Gus from this
QTH?
St. Kitts Island, Nevis Island and St. Vincent
Island all active under a VP2 call -sign, with
VP2KJ on Nevis Island active most evenings
around 2200 on 14Mc /s. Rumours of a group of
ODSs climbing up a mountain and signing OD¢.
J. Brown (Llandaff) bemoans DL /DJ s.s.b. nets
on 80. He also tells of VS6AJ on 3.798Mc /s s.s:b.
around 2300.
Contests for the merry month of November
include : 6 -7th, 7Mc /s DX contest (c.w.); 6 -7th,
4U2/4S7 contest ('phone); 13 -14th, second
432Mc /s contest; 20 -21st, second 1.8Mc /s contest;
28 -29th, CQWW contest (c.w.). Many thanks for
the logs. Always pleased to hear from you.
Deadline for this month 27th.
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
LEARN
ELECTRONICS
-AS YOU BUILD
CIRCUITS
over EXPERIMENTS
TEST GEAR
including . . .
CATHODE RAY
Valve Experiments
Transistor Experiments
Electro- magnetic Experiments
Basic Amplifier
Basic Oscillator
Basic Rectifier
Signal Tracer
Simple Counter
Time Delay Circuits
703
OSCILLOSCOPE
e Square Wave generator
Morse Code Oscillator
Simple Transmitter
Electronic Switch
Photo -electric circuit
Basic Computer Circuit
Basic radio receiver
A.C. Experiments
O D.C. Experiments
The full equipment supplied comprises: valves, transistors, photo -tube, modern type chassis board; printed circuit board; full range
resistors, capacitors and inductors; transformers; potentiometers; switches; transistors; valves; all hardware, wiring and every detail
required for all practical work plus CATHODE RAT OSCILLOSCOPE for demonstrating results of all experiments carried out. All practical
work fully described in comprehensive PRACTICAL MANUALS. Tutor service and advice if needed.
This complete practical course will teach you all the basic principles of electronics by carrying out
experiments and building operational apparatus. You will learn how to recognise and handle all
types of modern components; their symbols and how to read a completed circuit or schematic diagram.
The course then shows how all the basic electronic circuits are constructed and used, and HOW THEY
ACTUALLY WORK BY USING THE OSCILLOSCOPE PROVIDED. An application is given in all the main fields of
electronics, i.e. Radio; control circuits; computers and automation; photoelectrics; counters, etc., and
rules and procedure for fault finding and servicing of all types of electronic equipment.
NO PREVIOUS KNOWLEDGE NEEDED
SENT IN ATTRACTIVE BOX
NO MATHS USED OR NEEDED REASONABLE FEE -NO EXTRAS REQUIRED
COMPLETE ADVICE SERVICE O EVERYTHING REMAINS YOUR OWN PROPERTY
A completely NEW up -to -date
home study experimental
r POST NOW FOR FREE BROCHURE I
To BRITISH NATIONAL RADIO SCHOOL, READING, BERKSHIRE. Please send
course by .ree Brochure, without obligation, to:
BRITISH NATIONAL NAME
RADIO SCHOOL - ADDRESS
Britain's Leading Electronic Block Capitals Please I
Training Organisation. OR WRITE IF YOU PREFER NOT TO CUT COUPON PW 12.65. !
L
www.americanradiohistory.com
704 PRACTICAL WIRELESS
An
integrated
hi -fi turntable
unit from only 11 gns ?
YES!
Only Goldring's 60 years of experience of making
gramophone turntables and pick -ups could lead to
a unit like this ... the ideal integrated turntable, arm
and pick -up for do- it- yourself hi -fi aspirants... at
such a modest price. Just look at the features of this
remarkable G.66 unit:
Silent, specially made Swiss mains motor. Pressed
steel turntable on precision bearings evens out mains
current fluctuations. Die -cast light alloy arm with full
stylus pressure adjustment. Plug -in head shell, wired
for mono and stereo, takes alternative pick -up cart-
ridges. Eddy -current speed control (as fitted on some
professional units) varies the four standard speeds
by ± 10 %. Pick -up raising /lowering device coupled
to on /off switch and idler -wheel disengagement
mechanism. Deck size 12#' x 10'.
See the Goldring G.66 at your dealers -or write for
descriptive leaflet.
THE GOLDRING G.66
G.66/M X.2 £9.18. 8 + £1.12.4 P.T. £11.11.0
G.66/CS.80 £10.10. 0 + £1.14.2 P.T. £12. 4.2
G.66/CS.90 £12.12.10 + £2. 1.2 P.T. £14.14.0
Goldring Manufacturing Co. (GB) Ltd.,
486 -488 High Road, Leytonstone, London Ell
Telephone: Leytonstone 8343
December, 1965
RETURN -OF -POST
ON CASH OR C.O.D. ORDERS
GARRARD GRAMOPHONE EQUIPMENT
Credit Terwu
Cash Price Deposit Monthly Total
Payments Credit
59.19.6 51.19.6 12 of 15/5 511. 4.6
28. 9.6 51.18.6 12 of 13/5 59.14.8
RECORD CHANGERS
Model 50 (G0ß Mono PU)
Model 1000 (GCS Mono PU)
Model 3000 (9TAHC Stereo/
Mono PU) 512.15.0
AT80 (GC8 Mono PU) 212.19.6
A70 Deram PU) .. .. 225.19.6
LAB80 (Denim PU) 531.19.6
SINGLE RECORD PLAYERS
SP25 (OCR Mono PU) 212.15.0 22.12.0 12 of 19/2 214. 0.0
SP25 (Derain PU) . 216.10.0 53. 6.0 12 of 24/9 518. 8.0
IMPORTANT -When ordering units with the Deeca Demur Pick -Up,
please state whether Stereo or Mono required.
ARMSTRONG CHASSIS
127M AM /FM Tuner Ampli-
fier .. 228.10.0 55.10.0 12 of 39/4 529. 2.0
224 FM Toner , 522.10.0 84.10.0 12 of 38/9 224.15.0
MULLARD AMPLIFIER KITS
We ha.e full stocks of all components for the Nullard 510. 3 -3, Two and
Three Valve Pre- Amplitiers,Tape Pre -Amplifier. Steteo Pre -Amplifier,
Seven Watt and Three Valve Stereo Amplifiers all as described in the
Mollard Manual for Audio Circuits. We can supply this publication for
9/6, poet free.
ILLUSTRATED LISTS
Illustrated priee riots are available free on Loudspeakers, Gramophone
Equipment, Martin Audio Kits and Test Equipment. Please send 4d. stamp
for postage.
COMPONENT BARGAINS
Nullard OA81 Diodes, 1/6 each.
Condensers, Silver Mica: 15pí, 18p1, 22pf, 39pí, 47p1, 88pí, 82pí, 120p1,
180pí, 270p1, 470pí. 680pí, 820pf, All 4d. each. 8/6 dozen.
Midget Ceramic: 1000pí, 4d. each. 8/6 dozen.
Polyester, Muliard:.002mfd., 400v., Bd. each, 5/8 dozen.
TCC and Dubilier Metalpack:.lmid., 500v., 6d. each. 6/- dozen,
Moulded Mica: 20p1, .001mid., 3d each, 2/6 dozen.
Small tag stripe. Assorted packet 2/e. Postage extra on W the above
components.
MARTIN AUDIO KITS
Complete transistorised Hl -Fi Pre -Amplifier and Nain Amplifier com-
prising Unit 1, (Five -way input selector). Unit 4 (Pre -Amp. with volume,
base and treble controls). Unit 7 (10 watt Main Amplifier, 15 ohm output),
Unit 8 (Power Unit) and smart plastic Escutcheon. All unite are assembled
and tested and the constructor ha. only to link the various unite together.
Full instruction. supplied. Cash Price 215.8.0. Credit terms. Deposit
53.2.0 and 12 monthly payments of 51,8.0. Total Credit Price 516.18,0,
Stereo and other Mono Units available, Full list tree on request.
MARTIN FM TUNER KIT
Transistorised FM Tuner Kit for use with the above Martin Audio Hait and
most other Amplifiers. Supplied ready assembled In unit form and tested.
The constructor has only to link together and mount the mite. Full
instructions supplied. Cash Price 212.17.6. Credit terms- Deposit 62.11.8
and 12 monthly payments of 19/4. Total Credit Price 114.8.8.
LOUDSPEAKERS
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WATTS RADIO Ordr) LTD
54 CHURCH STREET,
WEYBRIDGE, SURREY
Telephone: Weybridge 47556
Plano nata; Postal bonnets only tram this nddra-
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 705
REMEMBER those word -
association games we once
played? When someone snapped
" Pen " and we answered " Ink ",
" Wood " ... " Tree ", "Chair "
" Sit ", " Bottle " ... " Uncle
George " and so on.
What would be your instant
reaction to "Tape"?
If you answer " Spool " let me
tell you that events have passed
you by. You should have said :
" Cassette ". At least so think
two large groups of tape
recorder manufacturers who are
doing their utmost to make
individual spools obsolescent.
Hints have been in the wind
for some time. The German
Radio Exhibition which took
place in Stuttgart while we were
still bemoaning our own sad loss
of a Radio Show has amply
confirmed our fears.
A consortium of famous
manufacturers. Blue Spot, Grun-
dig and Telefunken, have
developed a cassette -loading
system which is to be termed
DC International. The cassette
has two playing time sizes.
though the physical size is the
same i.e. 4; x 3 x in. Tape is
non -standard, just over fin. wide
and plays for either 90 or 120
minutes. using two tracks. Latest
models of the tape recorders of
these makers are to be designed
My Chicago Spy .. .
specifically to take this cassette.
That's all very fine but what
about all our precious tapes of
the family fun- feasts or the
church bells of Little Wittering
on a wet autumn Sunday that we
are preserving for the benefit of
posterity? Suppose we want the
advantage of the "tape recorder
for pretentious connoisseurs of
music" as Telefunken advertised
one of their latest to be?
We dare not open the cassette
and try to wind our tape in
place. Apart from the fact that
it is twice as wide these cassettes
operate on the "seesaw" prin-
ciple -the tape revolves on a
hub and as one hub fills the
other empties. Two similar spools
just could not fit.
So if we buy the latest our
tapes are out of date. Conversely
the cassette will not fit on any
tape recorder except those of the
consortium.
This is the next important
point. Lack of standardisation,
no less. We are by now familiar
with the Philips EL3300, a beau-
tiful little machine using a
cassette which came out in 1963.
It would be a naive hope that
one cassette would fit the other
machine or even vice versa. And
Philips are pushing on with their
cassette development.
So we now have two truly
international standards
to add to the shelf of boxed
tapes that we are always intend-
ing to tidy up. And, of course,
to keep up with the Ioneses a
second tape recorder, cassette
version, which was already obli-
gatory, now becomes two cassette
machines, one for each standard,
otherwise we shall not be able to
keep up with the repertoire of
pre -recorded tapes.
As the editor of one trade
magazine has already com-
mented : "This situation has all
the makings of a war rather than
a standard and, like war, it is
likely to destroy itself rather
than succeed".
No.16
What's
With Tape? .
Church bells on a wet Sunday
Funny thing, the dealers who
market one brand of tape are
being offered an attractive album
pack of spools of various sizes
decked out to look like a collec-
tion of first edition novels in a
tasty oak display shelf which
they keep as a bonus when the
tapes are all sold. Could it he
an enemy raiding party?
All this takes no account of
the next threat to our wallets-
video tape recording. Machines
at the Stuttgart show by Philips.
Grundig and Loewe -Opta are
now well below the £1,000 mark.
My spy at the Chicago Music
Show this summer informed me
that " videograms " (his term)
cost no more than top -quality
stereo outfits (one thousand
dollars -less than £350). I
wonder if they will find a way: of
fitting a cassette, too.
The editor of a leading tape
recorder magazine tells us:
we should still be recording at
60 and 30 i.p.s. on paper- backed
tape if the industry had stood
still. Cassette loading, like it or
nor, is here".
And I have not mentioned
Garrard yet, whose pioneer
efforts with a lin. standard
cassette . seemed to belie the
advertising story that " the user
doesn't like to fiddle with loose
ends". Lots of 'em did!
www.americanradiohistory.com
706 PRACTICAL WIRELESS December, 1965
A [OW-POWER D.C. INVERTER
By D. Bollen
WHEN equipment with mains valves, such as
small amplifiers and radio receivers, is to
be used away from a conventional power
supply the problem of a suitable source of h.t.
current arises.
Transistorised inverters provide an attractive
alternative to the noisy rotary converter and
vibrator because there are no sparking brushes or
contacts to cause electrical interference and they
are quiet in operation. However, the type
normally encountered has two power transistors
and a special transformer which, though powerful
and efficient, can be somewhat expensive to build.
This article deals with a simple, inexpensive
unit requiring only five standard components and
one power transistor. The output available is 5W,
sufficient for a surprisingly wide range of equip-
ment.
Circuit
The basis of the inverter is an ordinary mains
transformer with 6.3V and 4 or 5V heater
windings. These are used as collector and base
inductances in a straightforward common emitter
configuration with positive feedback or, in other
words, as an oscillator. In Fig. 2 the 2.2ktt
resistor initially negatively biases the base of the
transistor so that it conducts. When oscillation
commences the diode drives the base positive,
cutting off the transistor for part of the cycle. The
amount of positive bias thus created can be preset
Mains
b anstormer
Tri h R1
01
D1
VR1
Heat
sink
Paxolin
Fig. 1 (above): Method of mounting componenrs.
Fig. 2 (right): Inverter oscillator circuit.
by VR1 to achieve maximum battery economy
and a high conversion efficiency as well as limiting
the current drawn by the transistor to a safe value.
In the case of the XC141 or OC16 this should not
exceed l' -A.
The 250V primary is now available as an output
winding. Normally this is tapped to cover the
range 200 -250V. These taps can be utilised as
25V and 50V outputs. The original secondary
may be 250 -0 -250 or 350 -0-350. If the centre tap
is ignored this winding provides an output
suitable for Geiger tubes, electronic flash, cathode
ray tubes and other high -voltage devices. With
conventional voltage doubling techniques the
output can be increased as desired.
1f the secondary winding is used in the normal
way the indirectly heated full -wave rectifier
should draw its heater current from the battery
via a suitable dropper resistor of the correct value
and rating (Rx, Fig. 3) and 6.3V valves can, of
course, be fed directly from the battery.
An interesting idea, possible with a.c. -only
equipment where a mains transformer is already
on the chassis, is to mount transistor and heat sink
on the chassis as well and switch the heater
windings so that the equipment can be mains or
battery powered at will. Fig. 3 shows how the
switching could be arranged. If the 6.3V winding
has a centre tap the battery should not be
connected to chassis but left floating.
This will depend on the mains transformer used
Mains
transformer
225V
200V
AC.
250V
500V
250V
250V
-6V
D1
0A81
+ve
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 707
BENTLEY ACOUSTIC CORPORATION LTD.
Suppliers to H.M. Government. 38 CHALCOT ROAD, LONDON, N.VV.I etephone: PRIMROSE 9090
NEAREST UNDERGROUND: CHALK FARM. ALL GOODS LISTED BELOW ACTUALLY IN STOCK, ALL
GOODS ARE NEW, BEST QUALITY BRANDS ONLY, AND SUBJECT TO MAKERS' FULL GUARANTEE, PLEASE
NOTE THAT WE DO NOT SELL ITEMS FROM USED EQUIPMENT NOR MANUFACTURERS'SECONDS& REJECTS,
WI4ICI-I ARE OFTEN DESCRIBED AS "NEW AND TESTED" BUT HAVE A SHORT AND UNRELIABLE LIFE.
042 519
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144 1216
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1.470T 7/6
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12/-
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6I3Q5 4/8 6x4 8/9 20P5 11/8 AC2PENII/6 E1148 119 2138 8/9 ETZ41 516 RIO 15/. 078 3/9 A.P126 10/- 00206 10/8
6131.27A 7/8 6E5 5/3 25.6130 7/6 603PE1I/ EA30 1/6 EL37 12/8 1.63 3/- 1112 510 11101 19/8 AF127 9/8 Ocrn 27/6
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61387 26/. 625G 15/. 2595 7/9 DI) 24/3 EAC91 3/8 21,81 8/8 1,14310 916 RI8 9/6 I.P.811 9/. BY105 7/- 100 15/-
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WE REQUIRE FOR PROMPT CASH SETTLEMENT ALL TYPES OF VALVES, LOOSE OR BOXED. BUT MUST BE NEW
METAL RECTIFIERS. DRM11O 13/-. DRM213 and DRMSB 15/8. LW7 21/-. LW15 28/-, RMO 7/11. EMI 5/3. RH) 6/8. R116 7/9. R514 12/8. RBI 17/8. 14486 17/13,
14697 19/6. 14.4100 28/.. 14A160 85/13. 1413130 31/, 103261 11/8. EC101 18/9. 161101.16.1 8/, 16011.2.2.8.1 11/, 16122.2.1.8.1 8/8. 18EA.1.1.8.1
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ELECTROLYTIC'S. Can types: 32 32:450v. N.. 50 x 60/350v. 8/-. 64 x 120/360v. 11/... 60 A 24032715v. 9/8. 100 A 400/275o. 12/6. 100/275, 8/-. 200076V. 4/-.
Ho A 200/275v. 8/6. Tiibuise types: 81450v. 1/9. 16/460v. 2/9. 32/460v. 8/9. 8 2 8/450v. 8/.. 18 A 163450v. 4/-. 32 x 32/350v. 4/... 8 x 16/450A. 8/9. 32/360v. 3/,
Midget silicon rectifiers. TyPeS =100. Output 250 volts 4 amp. No larger than a shirt button. 6/6 each. Series limiting resistance 1/6.
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708 PRACTICAL WIRELESS
BOOKS
New titles
SEPTEMBER
HI -FI PROJECTS FOR THE
HOBBYIST
by Leonard Feldman
Demy 8vo 128 pages 201- Net
101 WAYS TO USE YOUR AUDIO
TEST EQUIPMENT
by Robert G. Middleton
Demy 8vo 136 pages 181- Net
FUNDAMENTALS OF MODERN
SEMICONDUCTORS
by Barron Kemp & R. H. McDonald
Demy 8vo 160 pages 241- Net
SERVICING ELECTRONIC ORGANS
by Carl R. Pittman & Eugene J. Oliver
Demy 8ro 292 pages and 301- Net
Folding Diagram
HAM ANTENNA CONSTRUCTION
PROJECTS
by 1. A. Stanley
160 pages 241. Net
OCTOBER
BASIC ELECTRONICS SERIES
No. S RADIO CIRCUITS
by Thomas M. Adams
Demy 8ro 160 pages 241- Net
TROUBLESHOOTING WITH TEST
METERS (VOM & VTVM)
by Robert G. Middleton
Derny 8vo 160 J
pages 21/. Net
101 WAYS TO USE YOUR HAM
TEST EQUIPMENT
by Robert G. Middleton
Demy 8vo 168 pages 21/. Net
SOLID -STATE POWER SUPPLIES &
CONVERTERS
by Allan Lytel
Demy 8vo 112 pages 20/- Net
KNOW YOUR TEST METERS
(VOM & VTVM)
by Joseph A. Risse
Denny 8vs 144 pages 21/. Net
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DC INSTRUMENTATION
AMPLIFIERS
by L G128 George Lawrence
Demy 8vo pages 24/- Net
TRANSISTOR AF & RF CIRCUITS
by Allan Lytel
Demy 8vo 128 pages 24/- Net
INTRODUCTION TO TELEMETRY
by Alan Andrews
Demy 8vo 96 pages 18/- Net
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by John D. Lenk
Demy 8vo 128 pages 241. Net
ABC's OF TAPE RECORDING
by Norman H. Crowhurst
Demy öre 96 pages 16/- Net
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HANDBOOK (Sixth Edition)
Demy 8vo 128 pages 12/6 Net
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Size 6f in. x 4 }in. 96 pages 10/6 Net
ELECTRONIC SYSTEMS FOR
CONVENIENCE, SAFETY AND
ENJOYMENT
by Edward A. Altslwler
Demy 8vo 256 pages 30/. Net
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BASIC ELECTRICITY ELECTRONICS
Programmed Learning
6. LABORATORY WORKBOOK
Size 11 in. a 81in. 224 pages 351- Net
from Booksellers or, plus 8d. postage from
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Write for complete catalogue of over 100 tides
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TECHNICAL BOOKS
Dept. BPw Yeovil Road, Slough,
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NEW DEAL FOR AMATEURS
Every component is brand new. Accurate, tested
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plied to inhuma, miveraifiea, H.M. Poses etc.
The President 4 is a pocked size medium wave
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case, ferrite rod, 4 new Mallard semiconductors,
proper tuning condenser
proper plug -in
battery. Special re-
ties plus regen,ra-
tion circuit gives
performance equal
to 6 transistor Radio
(even operates a
speaker). Amazing
power, superb tone
-tunes into station
after station, home
and abroad. No
aerial or earth
needed -works \\
beautifully any- 29 6
II ` /
where at all!
Only 39/8 plus 2/64. p. & p. Everything-
including 4 Millard semiconductors, OC44,
0A70, 0071 & 0A70, personal earpiece, etc.
The Vice- President S is smaller stW -In last
there L no smaller! Bite only 1'/,x1slr,x }in.
Specially designed case, ferrite rod, covers W
medium waves, works anywhere indoors or
outdoors. Uses 3 new Mullard semiconductors-
0A90/91, 0044 and 0A90/91 in new reflex
circuit -pulls in Luzembourg. "Pirates ",
Foreigners eta and even this size uses Proper
Tuning Condenser! ONLY 29/8 phis 2/6 p. & p.
Everything -including 3 Mulatd eemicondue.
tors, personal earpiece etc. No more to pay.
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EDUCATIONAL ELECTRONIC CO. (EEPWS)
77 New Bond Street, Mayfair, London W.1.
December, 1965
SPECIAL RADIO
CHASSIS OFFERS
HI -FI CONTINENTAL
STEREOPHONIC RADIOGRAM CHASSIS
£7/19/0
Solve your communication
problems with this latest
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3 Subs), In deluxe plastic cabinets for desk or wall
mounting. Call/talk /listen from Master to Subs and
Subs to Master. Operates on one 9v. battery
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Office, Factory Workshop, Warehouse, Hospital,
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contacts. Complete with long connecting wires and
other accessorie,. Nothing else to buy. P. & P. 5 / -.
Magnificent 'Continental' Stereophonic
Radiogram Chassis with piano key switches,
built -in ferrite rod aerial. Complete with
two 10" elliptical loudspeakers, plus a mono/
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E29.19.6. Chassis only 19/ gns.
Special terms available of E4.10.0
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IMPERIAL HI-FI
STEREOPHONIC RADIOGRAM CHASSIS
The Imperial stereophonic 4 waveband
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www.americanradiohistory.com
December, 1965
and the intended application.
Obviously the layout will be
affected if rectifying and smooth-
ing components are included as
will usually be the case.
The transistor should be
bolted to a heat sink made of 18
s.w.g aluminium of at least four
square inches in area. In the
original construction both sink
and transformer were mounted
on thick paxolin so that mica and
insulating washers were not
needed to isolate the transistor
from its sink, which therefore
remains at collector potential.
The resistor, diode and capacitor
can be positioned on a small tag
panel which can be fixed on the
heat sink.
Setting Up
First connect an a.c. voltmeter,
in parallel with a 12kí2 5W resis-
tor, across the 250V primary
winding. With VR1 in the maxi-
mum resistance position and a
3A meter in the battery lead,
switch on. A hum or low whistle
will probably be heard, due to
the laminations of the trans-
former vibrating at the frequency
of oscillation. If there is no out-
put reverse either the 6.3V
winding or the 5V winding
whichever is the most convenient
to unsolder. When all is well de-
crease V R 1 and check both out-
put voltage and battery current
consumption until the optimum
ratio is achieved between the
two. It is emphasised that
with either of the transistors
specified the input current should not exceed 1.5A.
If the full 250V is not available with a load of
12k12 then a lower output power must be accepted.
The overall performance will depend to a large
extent on the suitability of the transformer and it
might well be worth while trying various types
before the unit is finalised. If maximum battery
economy is required when feeding a reasonably
constant load, resistance V R 1 can be increased.
For higher outputs, say above 5W, an 0C26
transistor could be substituted. This has a
collector current upper limit of 3.5A, but in this
PRACTICAL WIRFLFSS 709
o
Fig. 3: Switching for mainsi
battery arrangement.
A GIFT ON THE RIGHT WAVELENGTH
You'll be sending your Christmas message loud and clear if you
give friends who are fellow radio enthusiasts r. year's subscrip-
tion to PRACTICAL WIRELESS.
It's a gift you know they'll appreciate.
Simply send your friends' names and addresses, together with
your own and remittance' to -over each subscription to The
Subscription Manager (G.1), Practical Wireless, Tower House.
Southampton Street, London, W.C.2. We will despatch first
copies to arrive in time for Christmas, and send an attr_ctive
Christmas Greetings Card in your name to announce each gift.
Rates (including postage) for one year 112 issues): UK and
Overseas CI 9t: U.S.A. 54.25.
case it would be necessary to ensure that the 6.3V
heater winding was capable of carrying the extra
current, which might not he so in the case of some
smaller transformers. As a guide it can be taken
that the winding's current handling capacity is the
same as the maximum current available when the
transformer is being used in the normal manner.
Finally it is always preferable to switch off the
battery supply rather than to suddenly remove the
load on the output in order that undesirable
inverse voltage peaks are not developed across the
transistor.
PRACTICAL WIRELESS BINDERS!
The Pract cal Wireless Easi- binder is designed to
hold normally 12 issues, but it will accommodate
two additional copies quite comfortably.
A new version of the Easi- binder with a special
pocket for storing blueprints and data sheets is now
available. The price is I I /6d inclusive of postage.
Order your binder from: Binding Department,
George Newnes Ltd., Tower House, Southampton
Street, London, W.C.2.
www.americanradiohistory.com
710 PRACTICAL WIRELESS December, 1965
BOOKS REVIEWED
It DESIGN OF LOW NOISE TRANSISTOR INPUT
E CIRCUITS. William A. Rheinfelder. Iliffe Books Ltd.,
E. Dorset House, Stamford St., London, S.E.I.
160 pages. Size 5lin. x 84in. Price 30s.
F your knowledge of mathematics is not too hot,
you may well find difficulty in understanding
this book. About third -year maths in telecomms
gives you a sporting chance. Between its covers is
a very thorough discussion of noise with an
emphasis as the title implies, on transistors.
The first four chapter headings speak for them-
selves -Noise Figure Concept, Measurement of
Noise Figure, Noise of Spectral Discontinuity, and
Tube and Transistor Noise. Having discussed
noise and clarrified all obscure points, the author
then proceeds with a further four chapters on
design. These cover the whole frequency range
from receiver front ends up to 100Mc /s, design
above 100Mc /s and low noise audio design.
Chapter 8 being devoted to "Typical Low Noise
Circuits" which included circuits working at
800Mc /s and a low noise audio pre -amplifier.
William A. Rheinfelder is to be congratulated
on the professional and thorough way in which
this book was penned. Obviously well thought out,
the defining of terms, the thorough treatment of
noise in all its forms and the following up with
design details and typical circuits.-D.L.G.
E 101 MORE WAYS TO USE YOUR VOM AND VTVM.
= Robert G. Middleton. W. Foulsham & Co. Ltd., Slough,
Bucks. 128 pages. Size 84in. x Sfin. Price 20e.
THE book bears an honest title. It promises that
between its covers the reader will find 101
more ways to use these two pieces of useful
equipment, and indeed your reviewer counted
exactly that number. However some of these uses
are to say the least -unusual.
Use number 97, for instance held me spellbound
with how "To Check an Insect Electrocuter ".
Further uses described required other test gear
besides the VOM or VTVM. Audio oscillators,
grid dip meters etc. The crowning gem is Use
Number 73 which instructs how to check the con-
dition of a radio battery. Under its own heading
and in a paragraph all its own the book sternly
commands "Connect VOM test leads across
battery "!
This book contains some useful ideas but for my
money the author is rather scraping the barrel.-
D.L.G.
SIMPLIFIED MODERN FILTER DESIGN.
E Philip R. Greffa. Iliffe Books Ltd., Dorset House,
E Stamford St., London, S.E.I. 182 pages. Size 84 x 54in.
E Price SOs.
THIS may sound a rather dry book especially
for mathematical eggheads and with little or no
use for the average amateur enthusiast. Yet
these passive networks seem to creep into practi-
cally every corner of radio and electronics.
The audio enthusiast has bis equalising net-
works, the electronic organ enthusiasts wish to use
them in tone circuits. The " ham " uses low pass
and high pass filters, and attenuators are used in
many television installations.
This book covers a wide range of filter design.
but simplifies the maths by providing tables for
quick calculation and thus eliminates much of the
hard slogging. Designs are normalised for 111 ter-
minations and for cut-off at one radian per second.
Once design is completed it is scaled in frequency
and impedance and the end result is practical
filter design.
You will need a knowledge of maths for this
book. You will also need 50s. But if you want to
roll your own filters then this is a bargain. -L.S.A.
AMATEUR RADIO MOBILE BOOK.
E Charles Caringella, W6NJV. W. Foulsham & Co. Ltd.,
Slough, Bucks. 160 pages. Size 84in. x 54in. Price 24s.
HAVING attended various meetings and rallies
in the amateur radio world the writer can
vouch for the high standard set by the British
mobile ham station. These are the people at whom
this book will presumably be aimed, but I regret
to say that I fear this is one arrow which will fall
short of its mark.
The title is Amateur Radio Mobile Book, yet it
appears to be packed with photographs and dia-
grams of commercial American gear. In the 16-
page chapter on mobile antennae, there are eleven
photographs of commercial American equipment,
two of them taking a whole page.
Another chapter contains details of how to con-
struct a 6 -metre mobile transmitter. This is fine
until it is remembered that the British amateur is
not licensed to transmit on six metres!
This book represents very poor value for money.
and I can only urge would -be purchasers to see it
first.- L.S.A.
INTERNATIONAL RECTIFIER SOLARCELL AND
= PHOTOCELL HANDBOOK
E Application Engineering Department, International
E Rectifier Corporation. International Rectifier Company
(G.B.) Ltd., Hurst Green, Oxted, Surrey.
E 136 pages. Size gin. x bin. Price 20s.
THIS latest publication covering the field of
solar and photocell devices is printed and pub-
lished in the U.S.A., and therefore covers cells
manufactured in that country. However, Inter-
national Rectifier Semiconductor Centres are
established throughout the U.K. and all devices
mentioned are therefore available in this country.
Over 75 circuits are given covering a wide variety
of applications -light beam communication, secret
locks, photoelectric counters, fire alarms and audio
amplifiers -these are just a few of the many circuits
covered. Basic concepts plus a host of design data
is also included and make this a very interesting
publication.-M.S.C.
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 711
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ìB22 80/-
1CbGT 8/-
1D80T 8/-
1E7G 7/6
1F2 8/-
10641T 8/-
1L4 2/8
iLAB W-
ILCO 7/-
1L114 4/-
1N21B 4/-
1E43 4/-
1E70 4/-
1E4 6/-
1E5 8/6
184 5/-
18.5 4/8
1T4 2/-
2A3 6/-
:AS 81-
'2B26 8/-
2C20 7/-
2C'26A 3/-
2C34 2/6
2043 12/6
2ti45 22/8
2046 80/-
2061 12/-
2021 5/-
áAAá108A240i-
3A/48J 85/-
3A1167/M
26/-
3B7
3B24 6/-
:31)6 4/-
3E29 60/-
3Q4 8/-
3QSGT -/-
.'33v 6/9
3X2 3/-
4L"27 36/-
4D1 4/-
5A1730 5/-
5.41740 5/-
5B261M 26/-
SB264M 40/-
SR46Y 9/-
6T4 7/-
5U40 4/8
BV40 8/-
5X46 8/6
6Y3G 4/-
SY3GT 6/-
5Y3WGTB
6Z40 8/8
5Z46T 8/-
6AB8 4/-
UAC7 2/-
6405 2/8
6A07 8/-
6AHB 10/-
6AJ7 8/-
OAKS 6/-
4AK7 8/-
6AL6 81-
6AL6W 7/-
6AM5 2/6
6A1t6 4/-
BAQS 7/-
6AQ5W 9/-
6A86 4/-
6A86W 9/-
òA8741 20/-
BAT'6 8/8
6A D8 7/-
6414 8/-
6137 13/-
6B80 2/6
6BA6 4/-
6BA7 6/-
6BE8 4/3
6BJ7 7/-
6BQ7A 8/-
6BR7 9/-
fiBW6 9/-
604 2/-
6C60 2/8
6C5OT 8/-
606 4/-
6(60 3/-
4080 3/-
60H6 4/8
6021 80/-
8CL6 9/-
61)6 3/-
6B5O 6/3
6F6OT 6/9
6F60 4/-
6380 6/8
6E12 4/8
6F'13 5/-
6F14 5I-
EF71 7/B PY800 8/8 6F32 41-
EFT.: 5/- PZl % 9/- 65133 31-
EF73 5/- P7.1-76 12/- 606G 2/6
EF74 41- QP21 8/- 6H6M 1/8
EF80 6/- YA 4 QP26 5/- 6J4WA 101-
EF81 6/- QP230 6/- 5826511 86/- 656 6/-
, 1Iá 217 OTHER8 IX BTOC'6' /9elude Cathode Ray Tubes and 8p sveel Valves. AO U.K. ordere below P1,
MG 2/-
6,16 8
6.16W 8%e
6J7G 51-
fiJ7M 8/-
6KeOT 6/8
6K70 2/-
6K7GT 4/9
6K8U 8/-
OK8OT 8/8
K8M 618
61...50 6/-
6L60A 7/8
61.6M 11/-
61.70 4/-
61,34 4/8
6LD20 619
6N7 6/-
63170 5/9
BQ70 8/-
617 5/8
60A7 /-
68A70T 8/6
68K70T 4/-
6807 7/-
68070T 6/-
88FOT 5/8
68117 81-
68.77 6/-
BBJ7GT 6/8
60270 6/6
88K7 4/8
6BL7GT 6/8
68147 8/8
66Q7GT 6/-
0887 2/-
6U4GT 9/8
6V6G 6/-
6V6GT 7/6
6VBM 81-
OX4 3/8
6X50 5/-
6250T 5/8
6260 6/-
6-301.0 10/-
6Z4 6-
7B7 7/6
7C6 10/-
708 7/-
7C7 6/-
7E17 7/8
7Q7 7/-
727 6/-
7Z4 4/6
8122 "/8
9D^- 8/-
9D6 3/8
1.246 2/8
12AH7 6/-
12A118 11/-
12AT7 4/-
12407 6/-
124X7 6/-
12AY7 10/-
12846 6/-
MARCONI COMMUNICATION
RECEIVERS CR. ISO. Frequency
coverage 2 -60 Mc's in 5 bands. Two Ifs
Ist 1.600 kcs, 2nd 463 kc /s. Image signal
protetting over 40 dB up to 30 Ms and
20 -40 dB from 30-60 Mc /s. Self- checking
::alibration (built -in calibrator). Stabilisa-
tion of supply and temperature com-
pensation. Electrical and mechanical
indicator Bandpass from 100 c/s to 10 kc /s
bandspread. Metering and visual tuning
in 5 stages. Acoustic filter associated with
100 c/s. Bandpass position for CW recep-
tion. Facilities for diversity reception.
E;ccellent checked condition, 239. Mains
P.S.U. by P.C. Radio 24.10.0 Carriage 30'-
CR.150l2. Frequency coverage 1.5 -22 Mc, s
in 4 bands, all -other features as in CR.150.
Price E31. Carriage 303 -.
P.C. RADIO'S mains P.S.U. for above,
90f -.
H.R.O. SENIOR TABLE MODEL in
excellent, fully checked and tested con-
dition together with set of 8 general
coverage coils and mains P.S.U. 228.
Carriage and Packing 30/ -,
ORIGINAL MAINS POWER
SUPPLY UNIT FOR H.R.O. RE-
CEIVER, 260,. I ISv. Brand New 65/-.
P. & P. S/ -.
VERY HIGH CLASS COMMUNI-
CATION RECEIVER TYPE BRT
402E. 150 kc ¡s -385 kc /s., 510 kc /s -30 me /s.
Fully tested 260. Carriage 301 -.
EVERSHED MEGGER CIRCUIT
TESTER. 2 ranges 0 to 1,00052, 10051
co 200,0000. With test leads, leacher
carrying case. Tested 24.19.6. P. & P. 3x6.
C.O.D. 2/0 extra Overseas Postage extra at cos
PANEL METERS (round)
500mV 31" DC 35 -
500mA 21" DC 2236
500 microamp 2 DC 19 -
0 -500 microamp AC 35 -
0 -500 microamp 21' D.C. 22/6
0 -1 mAe 2" D.C. 19'6
25 -0.25 mA 21" D.C. 45f-
150-0 -1500 mA 3" D.C. 29f-
0-500 mV 31" D.C. 32/6
0 -5 V 31" A.C. 22/6
0-15 V 2" A.C. 17/6
0-50 V it D.C. 281-
0 -150 V 2F A.C. 241-
0.10 kV 23" D.C. 63/-
'Projection type.
2 KW ULTRASONIC GENERATOR
together with power supply unit for
200-250v. A.C. Complete two chassis with
interconnecting cables. Frequency 37 to
43 kc /s adjusted by One control. Peak
output 2kw, average output 500w. Com-
pletely new with valves and manuals E65.
Carriage paid U.K.
VARIOMETER for No. 19 set, 17/6,
P. & P. 3/ -.
AR88D RECEIVERS. Fully recondition-
ed, 155, rebuilt models E85. Carriage
paid U.K.
P.C. RADIO LTD
170 GOLDHAWK ROAD, W.12.
Shepherd's Bus{, 4946 -
Open 9 -9.30 p.m. Thursday 9 -1 p.m.
12BE6 71-
12867 7/-
1208 8/-
12116 2/-
12J6OT 8/6
122707 6/6
12K70T 2/-
12K8M 10/-
134170T 8/8
12047 7/-
12807 4/-
12807 8/-
12907 8/-
128.17 9,-
12BK70T8/-
128NTOT 9/9
128E7 á/-
12Y4 2/-
121.7 7/-
1802 6/-
1902 16 /-
1903 10/-
1906 9/-
1907 5/-
1901 6/-
19111 5/-
20P4 18/-
2186 9/-
251ú0T 6/-
26Yß 6/-
26246 8/8
2625 7/8
-626GT 8/6
261)7 6/-
30 30012 9/6
30E5 8/6
30FL1 10/6
30'19 12 /-
30PLI 8/-
3ß180T 7/-
36T 17/8
á5W4 5/-
3523 6/-
3524GT 6/-
352ß0T 0/-
88 4/-
41MP 4/-
44Á/168x 80/-
21550 ó/-
501.60T ß/-
53A 7/8
37 8/-
68 6/-
76 616
77 6/6
78 6/6
89 8/-
P. A P, II ; over 61. 3/-:
84 8/- C.R. Tubes
86A2 8/- CV1690
210VPT /09J) 66/-
--Ple 8/0 114504/B; D,
281-
220TH 4/- VCR97 28/-
9/- VCR13.30l-
307A /6 VCRI38A
'ilOC 2 I- 40/-
350B 8/- VCR139A
2ti84 1551/.. n11n11411713 17 /
4464 B/- VCR617C4(11
7034 80/- 40/- f
7064 10/- 3BP1 80/-
7158 601- 3FP7 461-
7174 3/- 3E01 40/--
724A - FP7A 121
80/- h
801 161el-
S61
803 00/0
807 81- Moto Tabu
808
811 17/ 8/6
G81-
CM68 6 12/5/6' 0
813 60/- 931A 68/-
816 86/- 6097 360/-
82921 80/-
601-
880B
829B 4/-
8321 46/-
83'1 16/-
883A 612 -
843 6/
81181 14/-
884
954 14/8
955 2/6
056 2/-
957 6/-
9584 4/-
1612 6/-
1616 6!-
1319 6/-
1626 8/-
1626 8/-
1629 4/8
2061 6/-
4043C 18/6
4063 8/-
78130 /- OC46
5704 809/- 0071 4/8 -
6726 6/- 0072 6/-
6060 5/- 0081- 71-
0064 0082 10/-
666.3 OC/22
6080 00/- OC260 10/8
7193 1/2 XC141 10/-
7475 2/- XC142 16/-
8013A 25/- X0166 82/-
90913 8/- 214156 92/e
8001 8/- 251602 47/-
9092 4/8 951247 9/8
9003 8/- 2E685 " 10/6
9004 2/6 9N1090 80Iß--
9006 2/8 2111091 89 -
over 68, P. 6 P. tree.
Bestial
Valves
ACTE 68
K302 14
KENIA 68.10.0
1824 26/-
2J22 62.10.0
2J54 68
417A 80 /-
3J /92 /E 687.10.0
714AY !A
725A SO/-
726A 18/-
T1naWóoea
0016 20 /. .
OC22 53/.'
0026 W-
0044 0/ -..
THERMAL PLUS MECHANICAL
CIRCUIT BREAKER FOR A.C. & D.C.
Current I amp. Protects against shorts
(instantaneous cut -out at approximately.
8 amps) and against overloads: 1.8 amp
30 seconds, 2.1 amp 15 seconds. 25 amp
8 seconds. Delayed cut-off may be ad.
lusted to different currents and timos.
Separate pair of contacts to indicating
device. Dimensions 31 x If x 7tt in.
Price 12'6. P. & P. 2/6.
SEMI- AUTOMATIC BATTERY
CHARGER "Baby Esstron ". Initial
charging rate 3.5 amps D.C. automatically
reducing to 1.5 or .lower (depending on
specific gravity of battery acid). As the bat-
tery receives the charge indication lights
indicate visually the high current or when
incorrectly connected. Meter incorporat-
ed. For 6 or 12v batteries. Mains voltage
200/240v A.C. Price E3 P. & P. 436.
A.R. 88D INSTRUCTION MAN-
UALS, 20/ -. P. & P. 2f6.
TELEPHONE HANDSET. Standard
G.P.O. type, new I2/ -. P. & P 2/ -.
NEW DHR. HIGH-RESISTANCE-
HEADPHONES. 14 + -. P. & P. If6.
WIRELESS SET No. 52 (CANADIAN)
Complete station consisting of Trans-
mitter. Receiver, supply unit for 12 v_-
All contained in special' carrier. 1.75 -16
me /s in 3 bands. 813 as output valve.
45 -75 w. phone and MCW, 70.100 watt
CW. M.O. or crystal. Receiver includes
crystal calibrator. Tx can be exactly
tuned to Rx frequency. Noise limiter.
Sidetone. Loudspeaker on receiver with
on /off switch. All brand new with acces-
sories. Export. Price on application.
www.americanradiohistory.com
712 PRACTICAL WIRELESS
HIGH QUALITY
LOWER COST
Combine an Armstrong Tuner and Amplifier and you
have all the advantages of separate units, plus com-
pactness, easier installation, and equivalent perform-
ance at a lower price.
Stereo model 127, above, derived from the more
expensive 227, has an identical AM -FM tuner section,
with an amplifier section designed for those whose
power requirements are more modest.
It has a more modest price too, as does the mono
version model I27M.
Each Armstrong Tuner -Amplifier is ideal as the basis
of a high fidelity system for radio and record
reproduction, tape recording, and playback, and each
unit may be built into your own cabinet or used in
our optional case, of teak and vinyl hide, as shown.
For full details and technical specifications of all
models plus list of over 300 stockists, post coupon or
write mentioning I2PW 65
model 127 STEREO TUNER AMPLIFIER L37.10.0
model 127M MONO TUNER AMPLIFIER L26.I0.0
optional case (3.10.0
ARMSTRONG AUDIO LTD - WARLTERS ROAD-N.7
Telephone: NORth 3213
Name
Address
12 PW 65
December, 1965
BARGAINS FROM
BROADWAY ELECTRONICS
TRANSISTORS: AF115, AF116. AFI17, 00170 all at 4/6 ea. 0C26
7/6. Mullard RF Packs 0C44 two 0045 12/6; AF Packs OC81D two
0081 8/6; 0C44 3/6; 0045 3/ -; 0071 2/6; 0072 3/ -' OA81 Diode 2/3;
ORP12 Light Cell 7/6.
TRANSISTOR ELECTROLY TICS: 1. 2, 4, 5, 8, 10, 16, 32, 50, 100
mid. all at 15 volts, 1/3 each.
EARPIECES with cord and 3.5 mm plug. 8 ohm magnetic 3 / -:
250 ohm 4/ -; 180 ohm magnetic with clip 6/6: Xtal 41 -.
GUITAR PICK -UP complete with clip and screened lead, 12/8.
B. M. 3. XTAL MIKE 30/ -: table stand for same 9 /6.
GARRARD A.T.6. Mono 28.19.6 Stereo 29.5.0. Autoslim
£5.10.0. New 1000 £6.15.0: Autoslim pick -up arm fitted with Ronette
Stereo only 25/ -; A.T.6 shells 6/6: GC8. GC2 cart. with brackets
15 /- ea. Motor Board 15 x 14ín. 12 mm ply cut out for Garrard or
B.S.R. changer, 7/6 ea.
Cabinets suitable for tape deck. A.T.6 etc.. 18 x 145 x Brin. covered in
red and black Rexine with carrying handle. 67 /6. Speaker cabinets
to match with sloping front to take 12in. speaker. 42/6; to take
loin. speaker, 37/6.
The "BLAKE" 12in. Heavy Duty Cabinet. Size 244 x 18 x 91n. The
Baffle is lin. thick. Plain white wood £3; covered in Rexine and
Vynair 851 -; De Luxe model veneered with wood grain Formica
and standing on smart lin. legs £5. Please add 10 /- for carriage.
"HAYDON" Cabinet. 165 x 15 x 75ín. Fabric covered, Suitable 12ín.
speaker 45/ -. Postage 7/6.
Vynair speaker cloth 50in. wide 14/- yard.
Rexine leather cloth 50in. wide 10/6 yard (S.A.E. for samples).
NEON PANEL LIGHTS. 240v A.C. Arcolectric, 2/6 ea.
TERMS: C.W.O. or C.O.D.
Plus post and packing charge. Garrard changers etc.. 6/-
Small parcels 6d.
BROADWAY ELECTRONICS
92 MITCHAM ROAD, TOOTING, S.W.17
Phone: BALham 3964
(four minutes from Tooting Broadway Underground Station)
EX- RENTAL TELEVISIONS
r>- 14 in, 17 in.
, ' E7.10.0 EII.I0.0
l - -
-
;'
I9í
-
12 months 3 star Guarantee
* Tube * Valves
* Components
Coloured FREE LIST
Channels for all areas
Demonstrations daily
from our
large selection
Personal collection or
Insured Carr.,
14 in. 20f -; 17ín. 30/-
ONE YEAR GUARANTEED
100% REGUNNED
Add IO'- or old tube. 21 In.
TUBES
'%
99/6 ca.
All Il0° -9916 +
301- refundable on 17 in.
OLD TUBE. Carr 79/6
1016_ 15,14
Slimline 17 and 59/6
19 inch.
Export Postage 301- 12 In.
EX- MAINTENANCE TESTED TUBES
17ií1. -355- Most makes and types available. I4in. -I5f-
Guaranteed good picture. Carriage 5f- extra.
TELEPH ONE
HANDSET
I Sí6
(1, S6 pair
G.P.O. pattern, House to
Workshop, Garage, Inter.
Office, etc. Works off any
small battery. P. @ P. 4/6
VALVES £1 per 100. Assorted T.V. and Radio.
Surplus ex- rental dismantled receivers. Post.
4/6. Send for list.
CONDENSERS 10/- per 100. New Assorted
Eiectrolytics and PFs. P. & P. 2/6.
RESISTORS 5/- per 100. New. Mostly High
Stabs. Assorted. P. & P. 2/ -. Overseas 3/6.
SPEAKERS 7/9. 61n., 8ím, 7 x Me., 8 e Sin.
Ex -mid. salvage. P. ß P. 2/3. Overseas 4/ -.
Phone DUKE & CO.(LONDON)LTD. Stamp
ILFord 621/3 Rumford Road, Manor Park, 1.12 For Free
6001/2/3 Liverpool St. -Manor Pk. -l0 mins. List
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 713
A SIMPLE 3 -VALVE SUPERHET
from the spares box
by J. B. Willmott
BASICALLY the circuit comprises a frequency
.changer stage, the i.f. output of which (at
465kc /s) is fed into on anode bend detector,
and the resultant a.f. signal passes to a conven-
tional pentode output stage, the whole being
supplied with power by means of a metal rectifier
for the h.t. supply, and a heater transformer to
feed the valve heaters and pilot bulbs. As half
wave rectification is employed, the chassis of the
necessity connected to one side of the mains
supply, but, this is standard practice and provided
the precautions described later in the text are
complied with, no danger will result.
Components
All the components listed are of standard
pattern, and freely available from advertisers in
this magazine. The only components of specific
manufacture are the tuning coils, by Messrs. Denco
Ltd. The heater transformer (T2) possesses small lugs
on the top portion of the clamping frame (see
Fig. 3) to which a metal clip securing the can of
the smoothing capacitor(s) is bolted. R11 and R10
can Conveniently be soldered directly across C14a,
b. c tags. Being thus mounted above the chassis,
they will be able to dissipate heat without damage
to wiring or nearby components.
A 5 in. diameter loudspeaker will nicely fit the
chassis, and will adequately handle the volume
required for domestic listening. A simple cord and
drum drive to the tuning capacitor, on whose
spindle is mounted a double ended pointer, in
conjunction with a two waveband glass dial
mounted in the receiver cabinet, gives station
indication. The on /off switch is combined with
the volume control, and a four pole, 2 -way
" Yaxley " type switch provides for wavechange
switching.
Before fixing the tuning capacitor solder
a piece of insulated connecting wire about 4 in.
long to each of the lower fixed plate contacts,
and thread these wires through the appropriate
holes in the chassis, so that connection can be
made later to the wavechange switch, etc. The
orientation of the valveholders should be care-
fully noted, constructors not familiar with the
British 7 -pin valveholder, are reminded that the
heater pins of these valves are Nos. 4 and 5;
numbering being in a clockwise direction, when
viewed from the underside of the valveholder, No.
I pin being the "odd one out ", and Nos. 4 and
5. those closest together. Note the presence of
solder tags on the fixing bolts of each valveholder,
Fig. II Complete circuit diagram.
E www.americanradiohistory.com
714 PRACTICAL WIRELESS December, 1965
44
11
t All other holes SBA clearance
Sfe Bend down
7 along dotted line
713.
Cut-out for _ _
cord drive D
`P
E
1"
171;
71;
212
A 14. dia hole
Hole sizes t B 11 dia. hole
C 34 dia hole
dla. hole
E. _ABA clearenee.
lot¢
.Bend
214 d wn.
dotted
line
Fig. 2: Chassis drilling details.
adjacent to the heater pins, also on one of the
loudspeaker fixing bolts.
The tuning coils should preferably be the last
components placed in position, as they may be
easily damaged by rough handling. The manu-
facturers point out that the plastic fixing nuts
should be fastened up with care, finger tight, as
undue forcing may cause the threaded portion of
the coil former to be pulled off the body. The
screening cans supplied with the coils are not used
in this design, as space is at a premium, and in
any case, as the coils in use at any one time
are operating on widely divergent frequencies,
there is no danger of instability by feedback from
unscreened coils.
The drive from the tuning spindle to the tuning
capacitor is of conventional pattern, being formed
by wrapping the nylon drive cord twice round
the drive spindle to secure a good grip, one end
is anchored to the lug on the drive drum, the
other end via a tension spring, to the other lug
thereon. The length of cord should be adjusted
so that the tension spring is extended slightly,
and a firm slip -free drive should result. The drive
drum should be secured to the gang capacitor
spindle in such a position that the vanes can be
moved from the fully open to fully closed position
smoothly and without strain on the drive cord.
A metal backplate, pierced with a } in. hole to
accommodate the gang spindle, is secured to the
chassis front runner. This backplate can be easily
made from aluminium or tinplate. It should be
painted matt black, or other dark colour, so that
the brass double ended pointer (which is secured
by a small 6BA screw to the tapped end of the
gang spindle) shows up readily against it. The
glass dial is mounted in the cabinet itself, it can
be either glued into position, or held by small
metal clips screwed to the cabinet interior when
a wooden cabinet is used.
It is important to remember that one side of
the mains supply is connected directly to the
chassis of the receiver, and the following
precautions against shock hazard must be adhered
to. The receiver should be placed on an insulated
surface, such as dry wooden bench or table, and
the constructor should be standing on a dry floor
surface-so do not take your set out into the
garage as concrete floors are a notorious shock
risk. Fit insulated control knobs to each of the
control spindles, and prop the chassis up on one
end (the end nearest the heater transformer) in
such a way that it is unlikely to fall down as a
result of vibration or an accidental knock: plug
in and switch on. Turn up the volume control,
and at maximum setting a very slight " breathing "
sound should be audible; if there is a loud hum
or accompaniment of crackles, something is amiss;
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 715
TI/IAUDIO RDU/TY SffRIO71//RÎY
A High Fidelity All Transistor Stereo Amplifier providing
Incorporation Of 1114. sell, retest Slullard Iran +Mors hate
made possible the really outstanding performance figures
of this brilliant design. Compare them with other leading
makes currently asallable.
NOTE Rated output is m watts R.M.S. (continuous) which should not be
confused with 1.H.F.241. (momentary culses).
IO watts R.M.S. on each channel
INPUT SENSITIVITIES
for 10 watts R.M.S. into 15
ohms)
Pick -up Magnetic
3.5 m.v. 33 ), r.p.m.
7 m.v. 78 r.p.m.
Pick -up Crystal /Ceramic 400
OUTPUT (per channel)
10 watts R.M.S. Into 15
ohm load.
15 watts R.M.S. into 3.75
hm load.
TOTAL HARMONIC
DISTORTION
u.1á at 5 watts R.M.S. Into
0.3% at 10 watt° .15 ohm
R.M.S. 1.000 c.p.. ))) load
DAMPING FACTOR 20
FREQUENCY RESPONSE
t 14 dB 20 -20 000 c.p.s.
HUM AND NOISE -tom.
CROSS TALK -42dB to --53 as
MAINS INPUT SELECTION
100 -110- 120 -200- 210- 220 -240 v 50/
_0 c.o.s.
SEMI -CONDUCTORS
(per channel)
AC107 0C44(34 OC81Z(2), 0A5.
0C127Z, AD14P (2).
BASS CONTROLS
11 dB to -lo dB at 40 c.o.s.
TREBLE CONTROLS
-15 dB to -15 dB at 10 Refs.
EQUALISATION
Gram. to std. R.I.A.A. characteristic.
Tape head to std. C.C.LR. characteristic.
SIZE 121. 54-x81'
WEIGHT 1211b.
FILTER (S.eep Cut)
KO', S Reis t, Kei -.
Please send
SAE for
leaflet
The Pre -amplifier is based
on the Dinsdale Mkll
(W.W. Jan. 1965)
IT ELIMINATES THE NECESSITY OF
MATCHED INPUTS & COMPLICATED
SWITCHING ARRANGEMENTS. IT
ALSO PRODUCES CONDITIONS OF
MINIMUM NOISE AT HIGHEST
SENSITIVITIES.
Microphone 5 m.v.
Tape Head 2 m.v.
l Aux. (Radio Tuner. Tape Rec.
etc.) 100 m.v. (Above sensitivi-
ties will be doubled when out -
nut load Is 3-4 ohms).
INPUT SELECTOR
.)31i r.p.m., 78 r.p.m., Aux,
Mic, Tape Head.
INPUT SOCKETS
Magnetic P.U.,Crystal /Ceramic
Pick -up. Aux. Tape Head
Microphone.
Built to the highest standards employ-
ing latest materials and techniques
DESIGNED FOR EASE OF FITTING
IN CABINET OR FOR FREE-
STANDING USE.
Tested to. satlefactorY operation
in temperature of 50 °C. (120 F.)
EXPORT ENQUIRIES INVITED
Designed and developed by the
Audio Fidelity Group of Com-
panies.
Manufactured and Distributed by LINEAR PRODUCTS LTD. ELECTRON WORKS, ARMLET, LEEDS:'
VALVES SAME DAY SERVICE
NEW! TESTED! GUARANTEED!
SETS 1115 185, 1T4. Y84, OVO DAF91 DF91, DK91. DL93, ÚL94,
get of 4 for 15/ -. DAF96 DF96 DEN DLO6. 4 r 24/6.
1A70T 718 7C5 719 CL33 918 ECF82 6.- 511414 4/-
1H5GT 7/3 7C6 5l9 CYO 12/8 ECF86 1019 N18 5/8
1N5GT 7/9 7E17 4/9 DAC32 7'S EC1135 8/- PC95 6/8
184 4/9 9BW6 3/6 DAF96 8/9 ECH81 813 PC084 5/6
185 8/9 10F1 919 DCC90 6/9 ECL80 613 PCC89 9/6
1T4 1/9 lOLD12 7/8 DF33 7/9 ECL82 6/9 PCF80 6/8
2P 19/6 I2AT7 3/9 DF91 1/9 ECL86 8/6 PCl/82 6/9
3A5 619 O2AU7 4/9 DF96 61- EF39 3/9 PCF84 7/9
3Q9 5/6 12AX7 4/9 DH76 8/8 EF41 6/3 PCF86 818
384 4/9 12K7GT 8/6 01177 4/- EF80 4/9 PC0801 9/9
3V-+ 516 12K8GT 8/8 UHe1 12/8 EF85 5/- PCF802 9/9
51140 4/6 12Q76T 3/6 DK32 "If EF86 6/8 PCF805 8/-
5230T 4/11 19B060 6/9 DK9i 4/9 EF49 412 00132 6/3
52.40/0T6/9 20LI 11/9 141C92 8/- EF91 2/6 PCL83 91-
6/30L2 8/9 20P- 10/9 11K96 6/6 EF92 1/I PCL84 8/3
6AL5 2/- 20Pt 13/6 DL3:1 3/9 EF97 7/6 PC185 81-
6AMr 2/0 20P5 11,6 DL35 5/- EF183 8/9 PCL88 818
6AQ) 5/6 251.86T 4/8 DL92 4/I EL33 6/6 PENA4 9/6
6AT6 41- 25U4GT11/e 01.04 5'8 EL38 11/8 PEN383 9/8
4B46 416 30018 8/- DL96 61- EL41 8/9 PEN36C15/-
613E6 4/9 30F5 8/8 DY86 6/9 EL84 4/6 FFL200 17/6
6B116 il- 30FL. 9/6 DYA7 8/- EL95 5l- PL36 8/9
6BJ6 5/6 301.15 10/3 EABC80 6/- E51:34 8/6 PL81 6/9
6BW6 7'9 30L17 12/- EAF42 7/6 E51.44) 519 PL82 8/8
6F13 3/8 30P4 13/8 EB41 41- EMU 7/3 PL83 e/-
62'14 91- 30P12 7/8 EB91 2/- EM84 5/9 01284 6/3
6R76 148 30P19 18/6 EBC33 6/- E5187 6/6 PL500 141-
6K8G 4/8 30PL1 9/6 EBC41 6/6 EY51 6/3 PL80] 7/0
eK86T 7/6 30PL13 10/9 EBF80 6/- E Y86 8/ PX25 7/9
6P28 9/6 300L14 11/. EBF83 7/6 EZ40 6/9 PY32 8l9
6Q70 5/9 351,66T 6/3 EBF89 5/9 E7.41 6/6 FY33 8/0
e8L76T 4/0 35W4 4/6 ECC40 8/9 EZ80 4/- PY80 5/3
6V66 3/6 35Z46T 4!8 ECC81 3/9 F.Z81 4/6 PY81 5/3
6v66T 5/6 53KU 8/8 E0082 419 FW4/500813 PY82 5l-
62E4 3/6 80 418 ECC33 7/- 07.33 14/8 PY83 5/9
6X56T 818 6083 12/6 ECC84 6/8 6Z37 8/9 PY800 6I6
7B6 10/6 AZ31 9/3 E0085 5/8 KT81 8/8 TH210 9/6
7B7 7/9 B'te 4/6 EnF.O 7/6 M 11140015/- TTl"^;', 6/6 077 2/
TY86F 10/-
U25 8/6
U36 8/9
U47 8/6
1752 4/0
1154 8/9
U78 2/6
UI91 9/9
ii281 8/B
11301 10/9
13801 15/-
11ABC80 5/9
UAF4z 7/9
UBC41 6/2
UBC81 6/3
UBF80 8/-
UBF89 519
UCC84 81-
UCC85 6/0
UCF80 8/8
UCB42 71"
UCH81 6/6
1701.82 7/3
UCL83 8/9
UF41 6/9
UF42 4/6
UF85 6/8
UF89 5/9
U L41 7/3
Fi L44 15/-
UTA6 8/6
UL84 51-
UY41 4/9
UY85 4/5
VP4B 111-
W76 3/8
W77 2/-
Y70 24/8
READERS RADIO
24 COLBERG PLACE, and at 85 TORQUAY GARDENS
STAMFORD HILL REDBRIDGE, ILFORD
LONDON N.16. STA 4587 ESSEX. CRE 7441
Postage on 1 valve 9d. extra. On 2 valves or more postage 6d. per valve extra.
Any Parcel Insured against Damage is Transit 641. extra.
SHORT WAVE
MAGAZINE
Covers the whole field of Amateur Radio
Is now in its 28th Year and 23rd Volume
Runs 64 pages every Month
Circulates in more than 75 Countries
Is Independent and Unsubsidised
Prints Constructional, Practical and Theoreti-
cal Articles on Amateur Transmission
Includes Regular Activity Features
Is Entirely Devoted to Amateur Radio
Stocks most American Rodio Books and
Manuals
Costs 42s. a Year ($6.00 U.S.) by Subscription
Is obtainable to order through any Retail
Newsagent (3s. 6d.)
(Specimen Copy 3s. 6d.)
55 Victoria Street,
London, S.W.1.
www.americanradiohistory.com
716 PRACTICAL WIRELESS
BRAND NEW AM /FM (V.H.F.) RADIO
GRAM CHASSIS AT £13.13.0 (Carriage Paid)
4
Chassis vioc 15 x 61 x 51in. high. New manufacture. Dial 141 r tiu. lu 2
colours, predominantly cream. 200 -250v. A.C. only.
Pick -up. Est. Speaker. Av.. E.. and Dipole Socket.,. Five pushbuttane-
OFF L.W., M.W., F.M., and (Irons. Aligned and tested O.P. Transformer.
Tone; control. 1000 -1900 M.: 200.550 M.; 88 -98 Me /s. Valves EZ80 rect.;
ECH81. REFIS, EABC80, EL84, ECC85, 3-ohm speaker required.
10 x Sin. ELLIPTICAL SPEAKER 25/- to purchasers of this chassie.
TERMS: (Chassis) £3.10.0 down and 5 monthly payments of 82.4.0. Cheap
Room Dipole for V.H.F., 12/6. Feeder 8d. per yard.
ALTERNATIVE DESIGN. L.W. 1000 -1900 M.; B.W, (9 -15 Mc /s); M.W.
190.475 M.; V.R.P. 87 -100 Mc /e.; Gram position. Otherwise visitar to above
chemin. Price 815.15.0 (mer. paid). TEEMS: 83.10.0 down and 6 monthly
payment, of 82.4.0. Total H.P. price 816.14.0. Circuit diagram 2/8.
2 -VALVE GRAMOPHONE AMPLIFIER
Price 37/6 (P. & P. 2/6)
Overall sine 4' wide x 5' high x 54'. Volume and tone °octrole. Mains lead.
Screened lead input With output traosformer for 3-ohm. For sertes
Of connection to Garrard and B.S.R. Autochangers and Players, having 90v.
i tapping.
SCan also be supplied on fabric covered board with main transformer and
e' x 4' speaker at 55/ -. (P. & P. 5/ -).
3 -valve Gram. Amp. Board 14' it 75' (x21' overall). UY85, UCC85 and
1.11,84 with Speaker r x 4'. Price 60/ -. (P. & P. 61 -).
p BATTERY ELIMINATOR
p For 4 low consomption valves (98 range) 90v. 15mA and 1.4v. 125mA, 42/8.
(4/- post), 200 -250v. A O. Also for 250 mA. 1.4v. and 90v. 15 mA at same
Ì prie.. Two units to replace existing batteries.
ï TAPE RECORDER AMPLIFIER
Falfy baht. Front panel 12} x lin. Chaavis size 105 x 5 x Mn. Valves
Ì EF88, BOLOS and 2EL84. Controls (1) Mic. Vol. (2) Tuner /P.U. Vol.
A (3) Play baci- or monitor, (4) Tone. '2 teck sockets for Tuner /P.U. and
Mie- switch fa supeçimpnse. Separate power pack containing transi. and
t rectifier. For Coloro studio de.k only. Price 88.14.0 (go- P. A P,)
SELF- POWERLD V.H.F. TUNER CHASSIS.
t Covering 88.95 Mc /s, Mollard permes-
bility tuner. Dime. 8 e 8 a 61n. high.
t Valves ECC85, EAB080 and 2- EF89's
¿ with metal rectifier. Mains transformer.
Fully wired and tested ONLY 88.17.8
(cart. paid). Room dipole 12/6. Feeds.
Od. per yard.
PUSH -PULL O.P. AMPLIFIER
£5.5.0 (6/- Carr.)
Brand new 200 -240 A.C. mains.
d asBs, treble and vol. controls, with
valves RE80. ECC83 and 2 -EL84
Igiving full 8 w. Chassie 12 it 31 x
34in. With op. trans for 2 -3 ohm
speaker. Front panel (normally
screwed to chassie) may be removed
and used as -Plying panel ".
4-SPEED AUTOCHANGERS
BSR -17A14 85.19.8
GARRA RD AUTOSLIM 68.10.0
STEREO 07.5.0
AUTOSLIM DE LUXE ATO 210.19.0
STEREO 011.10.0
Carr. 5/- each
MULTIMETER KIT. 18,000 o.p.v. 25 range kit with
Weston 50,íA meter, only 85/ -. (2.5A range 4/- extra)
stamp for detalle.
MULTIMETEBS Illustrated leaflet on request
TK20A, 1000 0.9.v., 88/- post 2 / -; EPIOK, 10,000
o p.v., 87/6 post 2/.; EP30K 30,000 .p.e., 105/
P ost '2,16: EPSOK 50.000 o.p.v., 145 /- post l /6.
Leather case for EPIOK and EP3OK, 17/ -; EP5011,
22 /- poet 1;6
PRECISION WIREWOUND RESISTORS 1W 1 ohm
te 5K 1% 8/ -; to 20K, 4/8; 1% add 3d. Your value
wound to ordre.
HIGH STAB. RESISTORS 4W 1% 2 / -. Full standard
range 10 ohms to 10M, plue many special multi -
meter values 10,000 pF. 1,000 pF. 100 p Fe% 1/- ea.
Bridge Rectifier 15V 10OmA, 5/8.
Tuggle Swltehea SPCA. 118; DECO, 201
Ssliord L'Aliment Reo. 1mA, Omri, 8/6,
Westeclora, Wl, 10 for 2 / -.
PLANET INSTRUMENT CO.
2s 1W) DOMINION AVENUE. LEEDS, 7
.Jft¢
SUPER 6
LONG & MEDIUM WAVE
TRANSISTOR RADIO
December, 1965
A quality radio available as a kit ur ready built. The sparkling performance
and superb finish of the completed receiver give you value equivalent to a
412. 12. 0 commercial mode).
* All new parts.* 6 transistors and diode. * 350mW output. * Superhet
circuit Ferrite rod aerial. * Weymouth Radio printed circuit board.
* component positions and references printed ou back of board. * Nicely
styled woolen cabinet. 11 o 74 x 31 in. * Vinyl covered in various
colons,. * 6 x din. speaker giving good bass and treble response. * Fuit
Instruction booklet 2 / -. Free with kit. * LF. frequency 470 ke /s. * Lining
up service if required. * All parte supplied separately. Write for lat. S.A.E.
please. -* 9v. battery required. VT9 or P.P.9 (319 with kit).
PLUS 5/. POST COMPLETF. KIT ONLY £4.17.6
OR PULL? 85,'ILT 88.17.8 Poo 8 ran. Paid
V.H.F. Pre- ampiffier with high signal -noise ratio and gain of at least 3:1
under average fringe area conditions. Metal container 34 x 34 x 1f in. high.
with strap for eaves. loft or skirting fixing. 9 volt battery operated, using
traneistorAF114. Covers all Rritieh and some Continental stations. 88 to 108
Mc /s. Order with confidence of improved reception.
TRANSISTORS
Packet of 3 coded RF transistors (equivalent of 0044/5) 7/8 post paid.
Set of 6 transistors and diode with circuit diagram. Neatly packed in foam -
lined box: motel for presentation. 15/- post la d
4 TRANSISTOR
MINIATURE PUSH-
PULL AUDIO
AMPLIFIER HIGH
IMPEDANCE
PRINTED CIRCUIT, 4in. x 21in. x 151n. over transformers. Output for
8 -ohm speaker. Suitable for microphone, record player and Intercom.
9 volt battery required. Frequency range 100 ope. to 25 Kens. Push-pull
output. clans B. instruction sheet provided. idly wired ready for use.
Three types. 200mW 35) -: 500mW 41/ -; I,2W 87/6. (P. & P. 2/6 each).
AMERICAN BRAND RECORDING TAP.:
FULL! GUARANTEED AT RECORD LOW PRICES
MYLAR BASE
7in- Stand. play. 1,'200ft.
71e. Long play, 1,800ft.
lin. Double play. 1,200fí
541x. Double play. 1,800ft.
7in. Double play, 2,400ft.
Sin. Triple play, 450ft. (Plain white boxes)
54ín. Triple play, 600ft. (Plain white boxes)
4in. Triple play. 900ft. (Plain white boxes)
51n. Triple play, 1,800fí (Plain white boxes)
71e.. Triple play, 3.600fí (Unboxed)
ACETATE BASE
51n. Stand. play. 600ft. ... 8/- MESSAGE TAPES
7in. Stand. play, 1,200fí ., 11/- lin. Stand. play, 150ft.
51n. Long play. 900ft 10 /- lin. Long play 225fí ..,
51ín. Long play, 1.200ft. 12/8 Mn. Double play. 300ft. .,
71n. Long play, 1,800ft. 15/-
Postage 1,- per reel (4 or more post free)
12/8
19/8
22/6
8/8
14/-
22/8
42/8
75/-
8f8
4/11
7/8
GLADSTONE RADIO
66 ELMS ROAD, ALDERSHOT, Hants.
(2 minn. from Stition and Boses.) Andenhot 22240
CLOSED WEDNESDAY AFTERNOON
CATALOGUE 6d.
Rexret overseas orders cannot be executed
NOW IN ITS 11th REVISED EDITION . .
ELECTRICAL ENGINEER'S REFERENCE BOOK
A revised edition of this comprehensive thirty -three section stan-
dard reference work covering,all branches of electrical engineering.
New and thoroughly revised sections include materials; cables and
wires; wiring and installation; applied electronics; instruments and
measurements, etc. References are also made to many new aspects
including germanium and silicon; printed circuits; transformer wind-
ings and design; electronic motor control; cold- cathode lighting, etc.
The "Progress" section is again entirely new and includes an authori-
tative survey of recent extensions to power- station generating plant.
2,212 pages, 2,096 diagrams, over 300 photographs, 76 specialist
contributors, 33 sections, 1 1th Edition. 120s.
FROM ALL BOOKSELLERS ... or in case of di ffrcul ty 120s. post free from GEORGE
NE WNES LTD., TOWER HOUSE, SOUTHAMPTON STREET, LONDON, W.C.2
NEWNES
www.americanradiohistory.com
December, 1965 PRACTICAL
switch off and again check all wiring and com-
ponents. If the test meter is available, the h.t.
voltage can be checked, this should be about 240V
at C14a and about 200V at C14c. Tapping the
blade of a screwdriver on the control grid (pin 5)
of V3, should produce a healthy " hum " from
the speaker, whilst tapping the blade on the grid
(top cap) of VI or V2 should produce a loud
"click ". If these responses are obtained, you are
more than half way to success, and can confidently
attempt to receive some signals.
Wave
change S1 Tuning Voiyme
On Off
WIRELESS 717
Alignment
As those who own a generator will almost
certainly be fully conversant with the process of
alignment, it is not proposed to repeat the process
here. For the less fortunate, read on. Connect a
good aerial to Cl, switch to Long Waves (switch
anti -clockwise), and sweep the tuning capacitor
across the dial, when at some point there is every
chance of the BBC Light Programme on 1500
metres being heard, even if very faintly. If no
sound at all, considerable patience will be needed;
Glass dial mounted
in cabinet
Dial backplate"
fitted under
nuts on controls
IF.T.1
To
aerial
Fig. 3: Top chassis layout and wiring.
V Fixing bracket
A.C. `ì for Cl4apc
mains t'
TC3 TC4 51a
To To
C14(b) C14(c)
A.C.
mains supply
black Fixed
plates
L4
Sib
Leads to 51
from L1,L2
C
yellow L
V1
0
"-To A.C. mains
Fig. 4: Under chassis wiring diagram.
www.americanradiohistory.com
718 PRACTICAL WIRELESS
To V1,pin1j, To pin8 of Lt
oscillator
anode
To pin 8
of L4
A
Sia
(aerial)
To pin 8 of L2
S1b
(mixer
grid)
pp
. (d
t lr / A.
To pin 8 v \
aof L3 (oscillator
To fixed anode)
plates VC1b
e
To pin 1 of L4
á h
To aerial
via Cl
To pin 6
of Lt
S1c
(oscillator
grid)
in 6
L2
To fixed
plates
To pin? of L3 VC1a
Fig. 5: Wavechonge switch wiring.
first screw up all trimmers, then release them by
about two turns of the adjusting screw; set the
coil cores so that the brass adjusting screws pro-
trude about } in. above the formers. Now try
searching for the elusive Light Programme signal
once more; if still nothing is heard, screw up
TC3 a quarter turn and try again. Repeat the
process at " quarter turn intervals "; if nothing
can be heard at any setting of TC3, unscrew the
core of L3 about two turns and repeat the search-
ing process at various settings of TC3. As soon
as a signal is heard, adjust TC3 and L3 for
maximum loudness, then peak up by adjusting
TCI and LI, reducing the setting of the volume
control to keep the audible output as low as
possible. Now very carefully try the effect of
adjusting the cores of the i.f. transformer, first
in one direction, then in the other; but do not
move them more than two complete turns in any
direction, otherwise the " pre -aligned " setting of
approximately 465kc /s at which they left the
component supplier, will be hopelessly " lost ".
By now, the BBC Light Programme should be
received loud and clear, and by adjusting the core
of L3 and LI, it should be possible to ensure that
this occurs with the pointer indicating the correct
dial setting. Naturally this method will not give
accurate tracking " across the full long wave-
band, but as the BBC Light is normally the only
programme required on the Long Waveband, this
is of no disadvantage. Now switch to Medium
waves (clockwise), set the dial to either Radio
Luxemburg or the BBC Light (247 metres), and
adjust TC4 and TC2 until the programme is heard.
Now turn to the BBC Third Programme (on 464
metres), and adjust L4 and LI for best response.
Now return to Luxemburg
setting, and again adjust TC4 and
TC2. Repeat these adjustments
until no further improvement
can be gained, when you should
find that the receiver is quite sen-
sitive and " tracks " correctly at
all settings of the dial. A
reminder should perhaps be
given here that the specified
tuning capacitor of the 300pF
type which matches the " Denco"
coils, and not the more common
500pF pattern, must be employed
if stations are to tune in at correct
dial settings.
LW aerial
(blue range 1)
December, 1965
COMPONENTS LIST
Resistors:
R I 47kí2 R7 IOkí2
R2 47052 R8 100k52
R3 47k52 R9 39052
R4 10k0 RIO Ikí2 5W
RS 2.2Mí2 RH 50052 5W
R6 470kí2
All 0", IW unless otherwise stated.
Capacitors:
C I 0.001µF mica 750V
C2 0.1µF paper
C3 0.1µF paper
C4 100pF silver mica
C5 0.1µF paper
C6 110pF silver mica 5%
C7 350pF silver mica 5%
C8 0.1µF paper
C9 25µF 25V electrolytic
C10 300pF mica
CII 0.0IµF paper 500V
C I 2 25µF 25V electrolytic
CI3 0.005µF paper 500V
CI4 a, b, c 32+32+814.F electrolytic
CIS 0.25µF paper 750V
VC1a, b 300pF twin gang
TCI, 2, 3, 4 50pF compression trimmers.
Inductors and Transformers:
LI dual purpose coil, range I Blue
L2 dual purpose coil, range 2Blue
L3 dual purpose coil, range I Red
L4 dual purpose coil, range 2 Red
IFTI standard 465 kc /s with fly lead IFT6B/465
TI 40mA primary, matching 750052 to 352
speech coil
T2 230/250 primary 12.6V IA secondary
Valves:
VI I5D2
V2 8D2 V3 I2A6
Denço
(Clacton)
Ltd.
Miscellaneous:
VRI 500k0 with d.p. switch
SI 4p. 2w. MRI 250V 40mA (min.)
5in. p.m. speaker, 2 British 7 -pin valveholders,
international octal valveholder, grid clips,
chassis 10f x 4f x I *in., glass dial, back plate,
pointer, drive spindle (rear drive), drive drum,
nylon cord, tension spring, etc.
M.W aerial
(blue range 2) LW. osc. MW osc.
(red range 1) (red range 2)
To S1a
8)
To To To
b Sta 51b C5' To
To
x S1c
To S1 Std
Fig. 6: Details of coil connections.
To
S1c
Ü To
S1d
To R4,
C5
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 719
TRANSISTOR POCKET RADIOS
Idral Gifts -all supplied complete with personal earpiece,
bat tory and carrying case. Fully guaranteed. Post free.
BOY'S 2 TRANSISTOR MODEL (Illustrated)
In attractive plastic case. Size only 4 x 2¡ x lin.
2lin. speaker. Uses PP3 battery. Tunable over
full medium waveband. 39/6
BOY'S 4 TRANSISTOR MODEL 45/-
6 TRANSISTOR MODELS
In plastic case. 4 x 2¡ x lin. with 21in. speaker.
Uses PP3 type battery Tunable over full medium
waveband. 59/6
2 Waveband (Long and Medium) Model size 5 x 31 a liin..
cream /black plastic case. 89/6
FAMOUS MAKE TRANSISTOR RADIO
THE "STELLA"
7 transistor portable radio. Long.
Med. and Short wavebands. Fitted
tone swatch and sockets for per-
sonal earphone and external
aerial. chrome telescopic aerial
Uses four 1.5 v. torch batteries
Plastic cabinet in beige and red,
size 4 x 7 x Din. Excellent tone.
3in. p.m. speaker Comp. with shoulder stras and external aerial.
Full guarantee. List price 17 Gris.
WIRECOMP'S PRICE £9.19.6 P. & P. Sf
WONDERFUL BARGAIN FROM RUSSIA
THE "SOKOL"
7 transistor radio covering full Medium and Long wavebands
with exclusive rechargeable battery which can be recharged
from any 110/250 v. A.C. mains supply. Can also overate on PP3
type dry battery. High quality P.M. speaker. Ivory and black
plastic case with metal trim -size 6 x 31 x 1:- in. Sockets for
external aerial and earpiece. Complete with real leather case.
dry battery, rechargeable battery with mains connector, and
personal earpiece.
WIRECOMP'S PRICE £6.9.6 p. & P. 2x6
WIRECOMP'S BARGAIN STORE
48 Tottenham Court Road, London, W.I
Thousands of bargains: Transistor Radios- Record Players
-Tape Recorders -Radiograms -Rock Bottom Prices
THE "REALISTIC" 7
Transistorised Portable Receiver
made to the highest professional stan- 1
dard. Comprises 7 Mullard Trans. '
plus Crystal Diode. 350 milliwatt out-
put to 4in. speaker. -I.F. frequency
470 Kc /s -fully tunable over medium
am: long wavebands. Two -tone plastic acs
cabinet with handle -size 7 a 10 x 3 /in. '
fitted socket for car aerial. Complete ""<.-.,...,..,.... ,
with full instructions.
MAY BE BUILT £5.19.6 Ail p ersol separately
FOR parts
p. & P. 4/6 extra. (Circuit diagram 2/6, free if all parts bought,)
Also De Laze Model with superior PVC covered wood cabinet
and full view tuning dial. ONLY £1 EXTRA. AB, parts sold
separately. Battery 3/9 extra. P. & P. 4/6.
SINCLAIR SUPER MINIATURE POCKET RADIOS
THE MICRO-6. Pocket radio only N /,, x l'l,o x fin. Complete with
earphone and detailed construction data. Can be built for only.
59/6
THE SLIMI.INE. The new 2- transistor pocket radio size only
23 x 11 x lt1n. l'an be built for 49/6
INTERNATIONAL BRAND TAPE -Fully Guaranteed
ACETATE BASE
15/- 3in - 150ft. 3/8
17/6 3in. -225ft 4 /11
151- 31n.-300ft. .. 7/6
35/- 5in. Long play. 900ft 10 /-
22/6 5ifn. Long play. 1,200ft. 12/6
45/- 7in. Stand play, 1,200ft. 10 /-
12/6 7m. Lon : play. 1.800ft. 15 /-
19/6 P.V.C. BASE.
23/- 5in. Stand play, 660ft. 8/6
58 /8 afin. Stand play 840f f. 11 /8
ree:. 4 reels and over Post Free.
MY'LAIL BASE
31in. Triple play, 600ft.
41n. Triple play, 900ft.
5in. Double play. 1.200ft.
5in. Triple play. 1,800ft.
5iín. Double play, 1.860ft.
Min. Triple play, 2.403íc
lin. Stand play. 1.200ft.
lin. Long play 1,800ft.
lin. Double play, 2,400tt.
71n. Triple play, 3,600ft.
I'. & P. i/- extr per
323 EDGWARE RD., LONDON, W.2. AMBassador
7115
All Branches open all day Saturday Early closing Thursday
Your complete basic guide devoid of mathematics
and circuitry .. .
BEGINNER'S
GUIDE TO
COLOUR
TELEVISION
by Terence L. Squires, A.M.Brit.I.R.E.
Explains fully how the signals are created
in the television studios, how they are
transmitted and the techniques used to
receive and display them. Covers: His-
torical Outline - The Colour Signal - The
Chrominance Signal - Colour Trans-
mission - Receiving the Colour Signal -
Domestic Aerial Systems - The Receiver
Block Diagram - The SECAM Receiver
etc. 128 pages. 58 diagrams.
I5s. from ALL BOOKSELLERS
. - or, in case of difficulty, 16s. by post from George
Newnes Ltd., Tower House, Southampton St., London WC2.
NEWNES
378 HARROW RD., LONDON, W.9. cuN; am
9530
Mail Orders to the above r.ddrns for prompt service
GUITAR AMPLIFIERS
with TREMOLO
12 months' guarantee (valves 3 menthe)
Five lack cock'
it Inputs with
four separate
mixing volume
controls. High
gain of 10 milli -
volts makes it
suitable for all
I types of guitare
l and micro-
] phones- Bopa-
ate Baas and
Treble controls.
i Raster gain
control. Trem-
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depth controns.
Remote trem-
olo switch sock-
et. 7.5 and la
ohms outputs.
90 and 50
watt valves
ECC83, 50E83. E1.3í, f:I. i, ;Ziii. 15 watt valves ECp83, ECC83,
EL84, EL84. EZ81. Two extra valve, ECC83 used in the tremolo circuit.
Tremolo operates on on input only. Black and gold front panel (fitted
tremolo type only at presents Chassie finished silver grey hammer. Cover
with chrome handle= 35/. extra.
PRICES
se watt with tremolo 621.17.6
5o watt ess treniolo £1,.10,0
30 watt with tr,m lo 816.17.6
30 watt less tremolo 214.10.0
15 watt with tremolo 613.17.6
15 watt less tressais £11.10.0
Add carriage 10 /- an}, amplifier. Descriptive leaflet free, stamp app-
reciated. Suiteble speakers, Bakers 12 Guitar L.B. 0 gns. Bakers 15'
Group SO L.B. 18 gas. Carriage free.
Cash with order only regret no C.O.D. "No trade or export."
STROUD AUDIO
CASHES GREEN ROAD, STROUD, CLOS. STROUD 788.
www.americanradiohistory.com
720 PRACTICAL WIRELESS
"TELSTAR" OUR EVER- POPULAR I -VALVE
SHORT WAVE RADIO
Recelves speech and music
from all over the world. Price
includes valve and one col]
covering 40 -100 metres. Can
be extended to cover 10-100
metres. Can be converted to 2
or 3 valve and all -mains
speaker use. Total Building
All parts Costs 35/- P. & P. 2/-
available separately
Mains POWER PACKS
The ideal economical and safe way of running any Transistor
Radio, Record Player, Tape Recorder, Amplifier eta. from
A.C. Mains.
The MAJOR "Power The B I J O U "Power r
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c 2/6 39/6 Pet using tPPam type
coin-
41v. +441v. Two separate 42/6 p] te battery. ith special adap-
outputs. P. & P. 2/6 tor enabling you to
Please state outputs required reactivate your existing
All "Power Pius" units are corn- PP3 type bah 17/6
pletely isolated from mains by tery.
double wound transformer en-
suring 100% safety. P. & P. 2/6.
The "POP -6" 6 Transistor Portable 62/6
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case and earpiece. P & P.2/6
Really palls in chose pirate stations.
READY TO USE POCKET RADIO
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ONLY 9/11
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R.C.S. PRODUCTS (RADIO) LTD.
I l Oliver Rd., London, E.I7, (Mail Order only)
Export Trade Enquiries Invited
BBC2 (625 LINE) TV AERIALS
Mast Mounting Arrays, 9 element 451 -;
wide spaced high gain. 11 element 55/ -; 14
element 62/6. Wall Mounting with
Cranked Arm 9 element 60 / -; wide spaced.
high gain 11 element 67/6: 14 element
75! -. Chimney Arrays Complete, 9 ele-
ment 72/ -; wide spaced high gain, 11 ele-
ment 80 / -; 14 element 87/6. Loft Arrays,
7 element 32/6; wide spaced high gain, 11
element, with Tilting Arm, 62/6; 14 ele-
ment 70 /-. All high gain units have
special Multi -rod Reflector. Low loss
CO -axial cable 1/6 per yard. VHF tren-
sietor pre -amps from 75/ -.
BBC ITV - F.M. AERIALS
B.B.C. (Band 1). Tele-
scopio loft 21/ -. External
B/D 30/ --
LT.V. (Band 8). 3 Ele-
ment loft array 25 / -. 5
elemen t 35/ -, W allmoun t-
ing, 3 element 35/ -. 6
element 45/ -.
('ombtned B,Il.C.11.T.V.
Loft 1+3 41/3:1+5 4819;
Wall mounting 1 +3 56/3;
1 +5, 63/9; Chimney 1 +3,
63 /9. 1 +5, 71/3.
V HI1 transiator pre -amps
from 75/-.
F.M. (Bend 2). Loft S/D 12 /6. "H" 30 /-
8 element. 52/6. External units available
Co-ax cable 8d. yd.. Co -ax plugs, 1/3.
Outlet boxee 4/6. Diplexer Crossover
Boxes, 12/6. C. W O or C.O.D. P. & P. 3/6.
Send 611. stamps for illustrated lists.
K.V.A. ELECTRONICS (Dept PM.)
3b Godstone Road, Kenley, Surrey
LOD 2266
December, 1965
FOR VALVES - SEMI CONDUCTORS - METAL RECTIFIERS
NEW 1965/6 CATALOGUE
NOW AVAILABLE
56 PAGES SEND If- in stamps
FOR YOUR COPY
Trade catalogue available which
is of interest to schools, research
establishments, etc.
SEMI CONDUCTORS
ALPHA
AA 120 4/6 MATIOI 8/6 OAZ207 7/6
ACI13 5/6 MATI20 719 OAZ208 516
AC154 516 MATI21 8/6 OC35 12/-
AC I 55 40- NKTI42 0C42 61-
AC 156 5/6 (OC44) SI- 0C43 91-
AC157 V- NKT404 0C44 51-
AD140 25f- (OC35) I01- OC45 51-
ADT 140 IS/- 0A5 61- OC70 4/6
AFI14 I I f. OA6 5/6 OC7I 4/3
AFI I5 10/6 OA10 616 OC72 5/6
AFI16 101- 0A70 21- OC73 16f-
AFI Y7 9/6 0A73 2/- 0075 5/6
AF124 II/- 0A79 21- OC76 6t,
AFI25 10/6 0,481 21- 0077 9/6
AF126 10/- 0A85 2/- 0081 5/6
AF127 9/6 0A90 2/- 0033 4/-
ASY28 6/8 0A9 2/- 0014 516
BY100 7/6 0A95 316 0C139 81-
BYIf4 SI- 0A200 3/6 OC170 6/-
GETI 15 9/6 0A210 AP- OCI71 6/-
GETI f6 IV- OAZ203 7/6 OC200 7/6
MATI 00 719 OAZ204 7/6 OCP71 25/-
ALPHA RADIO SUPPLY CO.
103 LEEDS TERRACE, WINTOUN ST,
LEEDS 7.
fAHOUS FOR THIRTY YEARS for
SHORT -WAVE EQUIPMENT al QUALITY
SHORT-WAVE
KITS
H.A.C. were the original suppliers of Short-
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including Technical Corteges, Hospitals,
Public Schools, R.A.S'., Army Hams, eta,
IMPROVED 1965 RANGE
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Customers say: Tiefiuiteiy the best one -
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FULL RANGE of other kits atin available
including the famous model 'E'. price 77/ -.
Before ordering rail and inspect a demon -
airatios receiver or send for a deecripti.r
catalogue and order form to:-
"H.A.C." SHORT -WAVE PRODUCTS
(Dept. P.W ), 44 Old Bond It., Loadas W.1
SERVICING
ELECTRONIC ORGANS
A practical guide for the service
technician who is servicing
electronic organs.
by C. R. Pittman & E. J. Oliver
30/- Postage
BASICTHEORY& APPLICATION
OF TRANSISTORS. U.S. Army.
Postage 1/-.
TROUBLESHOOTING WITH
TEST METERS (VOM & VTVM),
by R. G. Middleton. 211 -. Postage It -.
WORKED EXAMPLES IN ELEC-
TRONICS & TELECOMMUNI-
CATIONS, Vol. I, by B. Holdsworth
and Z. E. Jaworski. 251 -. Postage II -.
101 WAYS TO USE YOUR HAM
TEST EQUIPMENT, by R. G.
Middleton. 21f -. Postage If -.
TRANSISTOR RADIO SERVICE
MADE EASY, by W. Lemons. IS / -.
Postage If -.
RADIO & AUDIO SERVICING
HANDBOOK, by G. I. King. 25f -.
.'ostage 1%.
WIRELESS FOR BEGINNERS, by
G. L. Boltz. 181 -. Postage I1 -.
RADIO TELEVISION & ELEC.
TRICAL REPAIRS, by R. C. Norris.
501 -. Postage 2/ ,
COMPLETE CATALOGUE It -.
THE MODERN BOOK CO.
19 -21 PRAED STREET
LONDON, W.2.
Phone: PADdington 4185
Open 6 days 9-6 p.m.
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 721
No.2 PLYMOUTH RADIO CLUB
T HERE has been some sort of radio society in
Plymouth ever since 1926 but "The Plymouth
Radio Club " as now constituted dates from
1956, when the few staunch members of the local
" R.S.G.B. Group" broke away and formed the
P.R.C., affiliated to the R.S.G.B. Since that time
the Club has transformed from the informal
meeting of a few enthusiasts in a small room to
the current position of nearly 70 members with 35
licensed members.
Meetings are held every Tuesday throughout the
year except for the first two weeks in August,
when informal meetings are held on the world -
famous Plymouth Hoe. Three meetings every
month take the form of " organised " functions
such as lectures, discussions, business meetings,
etc., the fourth meeting being left free for " rag -
chewing" and informal discussions. Morse
classes are held every week prior to the
commencement of the evening's programme and a
team of experts can take any aspirant from 0 to
40 w.p.m. (or higher if desired). During the winter
months film shows are held once per month and
many of the latest and most advanced films -
technical or lay -are screened during the October
to April session.
There is a large amount of inter -club activity
in the South -West of England and apart from
many quizzes, informal social evenings, etc., we
organise an inter -club picnic on Dartmoor every
August. This is always a highly successful event.
Visitors on holiday and contingents from all the
Club station Le; t to right Clan "D" Wavemeter,
CR100, K.W. Geloso Converter, K.W. Vanguard.
surrounding area clubs are welcomed and enjoy an
unorganised but pleasant afternoon with amateurs,
wives, families, friends, SWLs, etc.
Our annual dinner and social evening is
usually held at the end of January or the begin-
ning of February each year and again on this
occasion many friends from contemporary clubs
are welcomed, the attendance usually being around
80. The highlight of this event is always the
" grand draw " when up to 50 valuable radio
prizes are offered. There is also a " ladies' draw",
together with a few speeches by the officers, a
little dancing and the evening usually passes all
too rapidly.
Whilst on the subject of officers a word about
them would not be out of place. The ranks of the
committee are, as in every radio club, microcosm
but including more than a few well -known .call -
signs. The president, GSZT, is probably best
known as the first person to make a two -way
contact by amateur television in the early 50's.
Decades ago, indeed before the war, he was a
pioneer of the h.f. bands and, whilst he achieved
post -war DXCC, the majority of his time
nowadays is spent on v.h.f., where he holds many
" firsts ", including the first -ever QSO GTOGC on
4m. The two vice -presidents are known for their
contributions to amateur radio away from these
shores -G3BRJ in the Far East, especially
Singapore, and G3WL has held many exotic calls
in YK, TA, SU, VP3, to mention but a few.
Between us all bands from 160m to 70cm are
actively used on all modes, c.w., a.m., SSB and
even RTTY.
There are many members in other parts of the
world, Singapore, Trinidad, Nigeria are again but
examples, to say nothing of the members in H.M.
Forces scattered abroad both within and outside
this island.
However, for all its other facets the hub of a
radio club is its station and the impression which
it portrays to other amateurs over the air. At one
time a "defunct" CR100 and a two -valve 160m
transmitter were its sole contents. However, when
the long- awaited call (G3PRC for Plymouth Radio
Club) was issued in 1962 then began the rapid
transformation from our humble beginnings of a
station to the somewhat different picture given by
the photograph. Basically the receiving side
comprises a " hotted-up" CR100 running from a
KW /Geloso -converter at 4.6Mc /s and the trans-
www.americanradiohistory.com
722 PRACTICAL WIRELESS
A recent quiz between Torbay A.R.S. and Plymouth R.C.
milting side a KW Vanguard. However, a great
deal of work has been put into designing the
station to our exact specifications. The console
operating position was built with ease of operating
over long periods in mind and all operations can
be performed by using the fingertip controls imme-
diately in front of the operator. The transmitter/
receiver set -up has been modified for full break on
c.w., with switching handled by " Londex " relays,
and for single switch control on 'phone -sidetone
is, of course, incorporated for the former mode.
The "Skywire" arrangements comprise a G5RV
fed with open wire tuned feeder for the " 34' down-
lead" section and then with low loss coaxial
cable. For the h.f. bands there is a G4ZU beam
fixed on the east.
Operations are roughly half 'phone and half
c.w. and there is a great deal of activity on all
bands, especially in contests during the winter DX
season. The R.S.G.B. National Field Day is a
must every year and a highlight in the Club
calendar. A certain amount of other portable
activity is indulged in -the station is operated at
the aforementioned annual picnic and also from
December, 1965
specially selected sites high up on
Dartmoor during a few week-
ends. The clubroom itself is situated
in Virginia House Settlement,
where we have our own accom-
modation. The meeting room
holds a coffee bar and the shack
is partitioned off. All the work,
console, station, Clubroom,
shack, etc., has been done by
members in their spare time.
Situated only a few hundred
yards from the Mayflower steps
whence sailed the " Pilgrim
Fathers" when they left to found
the United States in 1620 the
clubroom is in a part of old
Plymouth near the famous Barbi-
can and, indeed, inside the origi-
nal walls of the old " Sudtone "
which appears in the " Domesday Book " (a little
before radio!) and within easy walking distance of
the " Hoe" and we often go up to see Drake
playing bowls when operating /m!
So much for the past and present but what of
the future? Plans have been drawn up for a new
building with a radio shack and station drawn up
by the architects to our specifications. A lattice
tower will be built into the roof, an earth mat into
the floor and the shack will be separated from a
laboratory by a glass partition through which
measurements and readings can be made on the
test equipment on the laboratory bench. The
present station will be used to train novices, whilst
the new equipment will probably be on the lines
of a Collins "S" line or its equivalent in about
five years' time, when we can reasonably expect
these plans to materialise!
In the meantime we intend to fit s.s.b. to the
existing station by purchasing an SB10U which
will be built by our technical committee and will
enable the call -sign " G3PRC " to be broadcast
even further than the five continents and some 80
countries which have already been contacted.
A Transistorised S.W. Converter -continued from page 689
core of L2 will be different for the two bands
(although this was not the case in the prototype),
but a suitable compromise can usually be found
with a little patience. When a setting has been
found for L2 core it should be set in place by
means of wax. The final adjustment to L3 is made
next, peaking up for maximum response with a
smooth coverage and the core then set in place.
It must be emphasised that the converter is only
suitable for use with a set which does not employ
a ferrite -rod aerial, and is reasonably insensitive
without an aerial as, of course, interference will
occur between the converter output and the M.W.
signals. In the original it was found necessary to
provide a little screening for the aerial coils of the
receiver to prevent breakthrough. However, with a
little care and attention to adequate screening
where required will ensure that breakthrough at
" I.F. " will be no problem.
All is not completely black for the ferrite aerial
set if one is prepared to go to drastic lengths. The
Cots
Turns
Wire
gauge
(enam)
swg.
L1 L2 L3 L4 L5 L8
tap 13t
from
earth at 50t 5t 150t lot
34 '34 34 34 42 34
Wound
over
L1
Wound
over
L3
Wound
over
L5
7Ç dia iron cored coil ódla air
cored coil
All coils close wound
Fig. 4: Coil winding data.
writer has found that the converter will work very
satisfactorily into the car aerial socket of his tran-
sistor radio which is screened by placing it inside
a biscuit tin!.
www.americanradiohistory.com
December, 1965
INCREASE YOUR EARNING
POWER AND JOB SECUR-
ITY WITH ONE OF THESE
LOW COST COURSES
NEW. No. 500 RADIO AND
TELEVISION COURSE 75;-
Here at last Is your ,pporl unity to own a most com-
plete course at a very modest cost! This expanded
course which now includes television as well as radio
repair training could get you started on a whole
new career!
The Radio Section of the course was ORIO [NALLY
DEVELOPED BY THE RADIO TECHNICAL
INSTITUTE, while the Television Servicing Course
has formed the basis of instruction provided by one
of the world's largest television and electronics
Compares lesson by lesson with some courses costing
ten times as much! You save because you receive
all the lemons at one time and are not required to
purchase equipment you may not need.
The lessons are crystal clear. practical. easy to master
and use. Early lessons make fundamentals clear even
to the beginner. while other lesson. will give you the
practical know -how of an expert!
The new 500 Radio & Television Course consists of
352 large quarto sise pages of instruction. hundreds
of illustrations. We positively guarantee that you
will be delighted or your money refunded!
NEW. No. 600 RADIO- TELEVISION
ELECTRONICS COURSE 85,-
This is really big value in home training. Similar in
details to the above course excepting that you get an
extra 56 pages of instruction making a total of 408
quarto size pages. Hundreds of illustrations. Inclu-
des all the usual subjects plus Radio Transmitter
Circuits, Electronic Test Equipmeut, Thyratron
Tubes. Inter -Communicators, Sound Level Meters,
Servicing Printed Circuits and many more similar
Items. This course could be your first step into the
fascinating world of electronics!
No. 400. ELECTRONICS COURSE 45/-
A cump borne -.1.1y cnrsc of e 7lesson,. consists
of 216 large quarto size pages of in.irucl ion. tomes
complete with instructor's notes and test questions.
Thisis a modern course that teaches without resort-
ing to comic strip methods. Thousands M readers
of this magazine have taken this coerce and enjoyed
every minute of it... Why not you? Clip this
coupon for your free trial offer now!
No. 19. REFRIGERATION SERVICE
MANUAL 27/6
Learn refrigeration! This manual is packed solid with
information to enable you to start in refrigeration
right away! Used by many leading firms as a stand-
ard reference. Features 264 pages, 157 illustrations,
bound in cloth. An excellent book now offered for the
1ìr -t '
UNCONDITIONALLY GUARANTEED TO
GIVE COMPLETE SATISFACTION
Aug .,,sire o l mss t" returned within
to du, ¡cot-paid for full refund or credit of the pur-
chase price.
IF YOU SEND CASH WITH ORDER WE WILL
INCLUDE A FREE BOOK worth 4/6 to 5/- if
bought separately. By sending rash you reduce
book- keeping and other costs which we pass back to
you. But you must include cash at the time of order
to get this special offer!
* * * * FREE TRIAL OFFER * * * *
PAY ONLY 5/- per week if you wish.
To: SIM -TECH TECHNICAL BOOKS DEPT. G.I.
Gater's Mill, West End, Southampton, Hanta.
Please send the courses I have circled.
No. 500 No. 600 No. 400 No. 19
Si not delighted may return any book post -paid
without further obligation on my part. Otherwise I
will pay cash price sr 5/- weekly (10 /- fortnightly)
commencing not ater than 10 days after delivery.
am over 21 years of age. (If under 21 parents should
pace order).
1 enclose cash to the sum of F
I understand you will refund this
money if I am not 100;, satis-
fied and I return the book with-
in 10 days.
Please send me the free book(s) I have ticked.
Oscilloscope Book Electronic Gadgets Book
Transistor Book Radio Instrument Book
Name
Address
PRACTICAL WIRELESS 723
NEW VALVES
Guaranteed Set Tested
24-HOUR SERVICE
1R5, 1St, 1T4, 3S4, 3V4, DAF91, DF91, DK91,
DL92, DL94. SET OF 4, 141,
DAF96, DF96, DK96 DL96. SET OF 4, 23/6.
OA2 3/9 E1391 1/9 PL36 8/8
1115 4/- EBC41 6/3 PL61 6/6
1S5 3/3 EBF80 5/9 PL82 5/-
1T4 1/9 EBF89 5/9 PL83 5/11
3S4 4/3 ECC81 3/3 PL84 8/-
3V4 5/- ECC82 4l6 PY32 8/6
61C7G 1/3 ECC83 4/6 PY33 8/6
6101G 3/3 ECC85 5/3 PY80 4/9
607G 5/6 ECF82 5/9 PY81 5/-
6V6G 3/- ECH35 5/9 PY82 4/9
20P3 10/6 ECH42 7/9 FY83 5/3
20P4 13/- ECH81 5/6 PY800 5/11
201'5 11/6 ECI.80 5/11 U25 8/-
30FL1 9/3 ECL82 816 U26 8/6
30L15 9/9 FCL86 81 11191 9/6
'30PLI3 10/- EF39 3/6 U301 10/6
35L6GT 5/6 EF41 5/9 0801 14/9
85A2 5/9 EF80 4/3 UABC80 5/-
CL33 8/6 EF85 416 AF 12 6/11
DAC32 6/9 EF86 6/6 UBC41 6/-
DAF91 3/3 EF89 4/3 UBF80 5/6
DAF96 5/11 EF91 2/8 UBF39 5/9
DF33 7/8 EL41 6/9 UCC84 7/11
DF91 1/9 FL84 4/6 UCC85 6/-
DF96 5/11 EY51 5/11 UCF80 813
DK32 7/- F.Y86 516 UCH42 7/-
DK91 4/. F'7.40 5/6 UCH81 6/-
DK92 7/9 E780 3/9 UCL82 7/-
DL96 6/3 EZ81 4/3 UCL83 8/6
DL33 6/6 PCC84 5/6 UF41 6/6
DL35 4/9 PCC89 9/8 UF89 5/6
DL92 4/3 PCF80 6/3 UL41 7/-
DL94 5/- PCF32 81- UL84 4/9
DL96 5/11 PCF805 8/- UY41 3/11
DY 86 6/3 PCL82 6/3 UY85 419
DY87 7/3 PCL83 9/- WTT ll9
EABC80 5/6 PCL84 7/8 Z77 2/6
Postage on 1 valve 9d. extra. On 2 valves or
more. postage fid. per valve extra. Any
parcel insured against damage in transit
13,1. extra.
Office address. no caner,.
GERALD BERNARD
83 OSBALDESTON ROAD
STOKE NEWINGTON
LONDON Nib
ThePÿNc/
HOLE PUNCHES
Instant Type
" diameter . ... 6110 ea.
Screw -up Type
44" diameter Toggle switch ... 816
816 ,.
B7G ... 91. ,.
a- B8A, B9A... ... 916
-rub" ... ... ... 1012
. ... I0'8
II18
diameter Int. Octal... ... 1314
... ... ... 1612
., ... ... ... 18110
2118
2414
2y" Meter ... ... 3312
Complete Set £9.3.6.
No extra charge for postage and packing
in the U.K.
Now supplied by:
TOMPKINS & LONGMAN LTD.
237 GIPSY ROAD
WEST NORWOOD, S.E.27
Tel. Gipsy Hill 5000
rPLEASE GIVE,'
I MEASOLON I
I ELECTRIC
SOLDERING I
IRON FOR
CHRISTMAS "''
IOr perhaps you could
gently lead the conversation
round to it by saying how
many more jobs round the
house you could do. How
4 Solon are the best soldering
- irons. They last for years and
Ç all parts are replaceable.
al But remember, do say Solon
- electric soldering iron -get
'§ - her to repeat it after you-
., then you can be sure of
E getting the best. From your
, electrical supplier or
hardware store.
The 25 watt
Solon is a good
D - standard iron for
radio and
electronic work,
being light and
easy to handle.
N
7 O
1 T
i
A 65 watt model
with a round
pencil bit for the
handyman,
especially
suitable for
wiring
connections
and similar
lightwork.
i 'SOLON
www.americanradiohistory.com
724 PRACTICAL WIRELESS December, 1965
ANOTHER SINCLAIR
COMPLETE WITH
TELESCOPIC AERIAL
POLISHED AND
BRUSHED TWO -TONE
ALUMINIUM FRONT
PANEL
SPUN ALUMINIUM
TUNING CONTROL
ONE OUTPUT FOR
TAPE AND HI -FI
ONE OUTPUT FOR
PERSONAL LISTENING
The world's first
pocket -size FM
Tuner! Receiver
Sinclair's latest design, the SINCLAIR MICRO FM is a high quality
FM tuner designed to be used with hi -fi amplifier or tape recorder.
It can also be used independently as a self -contained pocket F.M.
receiver for personal listening anywhere. This exciting Sinclair
triumph, barely half the size of a packet of 20 cigarettes, is a fully
fledged 7 transistor -2 diode superhet circuit incorporating many
unique and original design features to achieve fantastically good
standards of performance. Pulse counting detection ensures better
linearity than conventional detection methods, and therefore
better audio quality. Powerful A.F.C. which locks on to the station
tuned in, together with unusually good sensitivity make tuning
easy and the set's own telescopic aerial suffices almost everywhere.
Separate output stages allow the unit to be used both as a tuner
and as a self -contained receiver. In styling, this is the most elegant, most
professional looking design in miniaturised equipment ever made available to
constructors, and is one you will be very proud to possess. YET WITH ALL
THESE WONDERFUL FEATURES, THE SINCLAIR MICRO
F.M. COSTS POUNDS LESS AND MEANS THAT ANYONE
CAN AFFORD AND ENJOY THE ADVANTAGES OF F.M.
RADIO TODAY.
ALL YOU EXPECT A HIGH QUALITY FM UNIT
TO BE, YET MEASURES ONLY 218 x I18 x 4 ins.
ANYONE CAN BUILD
THE - SINCLAIR MICRO FM
All you need is a small electric soldering iron (pre-
ferably with é in. bit), tweezers and something to
cut wire with such as nail clippers. The instructions
take you step by step through every stage and are a
delight to follow.
sinlair
FULL SERVICE
FACILITIES ALWAYS
AVAILABLE TO
SINCLAIR CUSTOMERS
SINCLAIR RADIONICS LTD.
Telephone
COMBERTON, _CAMBRIDGE COMB T&
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS 725
A.F.C.
TUNES FROM
88 -108 Mc s
NO ALIGNMENT
NECESSARY
A JOY TO BUILD
THE ONLY SET OF
ITS KIND IN THE
WORLD
SINCLAIR MICRO FM
7 TRANSISTOR SUPERHET FM TUNER/RECEIVER
TECHNICAL DESCRIPTION
THE SINCLAIR MICRO FM is a seven transistor, two diode F.M.
superhet for -use both as a tuner for amplifier or tape recorder and as a
self -contained pocket portable receiver. The telescopic aerial is coupled to
an R.F. amplifier followed by a self oscillating mixer. Use of a low I.F.
dispenses with the need for alignment. A three stage I.F. amf lifter amplifies
and limits the signal to produce a square wave of constant voltage which is
fed ino the pulse counting discriminator. This converts the -quare wave
formation into uniform pulses, the average output from which is directly
proportional to the signal frequency, so that the original modulation is
reproduced exactly. After equalisation, the signal is fed to the audio output
socket for use as a tuner and also to the receiver's own audio amplifying
stage which enables the Micro FM to be used as an independent self -con-
tained receiver. A.F.C. "locks" on each station automatically. THE SIN-
CLAIR MICRO FM is completely self- contained within a neat black plastic
case faced by an elegantly designed front panel of brushed and polished
solid aluminium with spun aluminium tuning dial to match. The tuning
scale is marked in Mc /s. When built, the Micro FM performs as well as any
other good tuner.
SUPPLY VOLTAGE 9V from self -
contained standard battery.
CONSUMPTION -5mA
SENSITIVITY -Typically 3 micro-
volts
AUDIO OUTPUT -300mV ap-
prox. from 25K ohms
THE GREATEST VALUE
THE COMPLETE KIT OF PARTS for
SINCLAIR MICRO FM including extend
transistors, case, tuning dial, aluminium
lightweight earpiece, plugs and sockets
tions costs only GUARANTEE
HIGH LEVEL AUDIO OUT -
PUT-9V peak to peak
TUNING RANGE -87.5 to 108
Mc /s
SIGNAL TO NOISE RATIO -
30dB at 30 microvolts
AUDIO FREQUENCY RES-
PONSE-10 to 20,000 cis -!- Id8
IN QUALITY FM EVER
building the
ing aerial, 7
front panel,
and instruc- f 5.19.6
Should you not be completely satisfied with
your purchase when you receive it from us.
your money will be refunded in full and at
once without questions.
ORDER FORM AND MORE SINCLAIR
DESIGNS ON PAGES FOLLOWING
Ilse it as-
AN P. M. TUNER
FOR YOUR TAPE
RECORDER .d
AS A SELF -
CONTAINED
POCKET P.M
RECEI VER..
www.americanradiohistory.com
726 PRACTICAL WIRELESS December, 1965
MORE UNIQUE DESIGNS FROM
BRILLIANT PERFORMANCE ADVANCED CIRCUITRY EASY
SINCLAIR X-20
INTEGRATED 20 WATT PULSE WIDTH
MODULATED AMPLIFIER AND PRE -AMP
20 WATTS R.M.S. OUTPUT
The most powerful hi -fi amplifier for its
size in the world
SIZE
f8l z"
4 1 x 3 4
x1'
weight
only
41 ozs.
X -20 MANUAL
Details various tone and volume control
systems, stereo operation, input switching
stage, eta Supplied FREE with every X -20,
'Available separately, 2f- post free.
By the use of Pulse Width Modulation in circuitry
developed exclusively by Sinclair Radionics, the unique
X -20 achieves standards never before reached by any
audio amplifier in the world. From the input of the
integrated pre -amp through to the power output stage,
this amazing amplifier gives quality and power far ahead
of anything in its class to make it the most original and
interesting design in years. You use your X -20 like any
conventional quality amplifier, but it occupies far less
space, costs less, behaves perfectly and brings a refresh-
ingly new approach to audio that is setting the standard
for the whole industry. Build it for yourself -you will
be delighted with the results, whilst its extremely
compact size enables you to build equipment in the
slimmest and most modern styling without heating or
ventilating problems.
* 12 transistors * Output into 7.5 ohms
* Output stage - silicon 20 watts R.M.S. music
epitaxial planars power
* Constant square wave IS watts R.M.S. con -
amplitude ti
* 95% conversion efficiency * Output into 1S ohms
at output 15 watts R.M.S. music
* Superb quality and re- value
liability IO watts R.M.S. coo-
* 20 to 20,000 c/s ± IdB ti
Total harmonic distortion * Makes ideal guitar or P.A.
* -0.1 % at IO watts R.M.S. amplifier
* Built -in low-pass filter
* Input sensitivity - ImV ensures wide tolerance
into 5k13 load at output
* Signal to noise ratio- * Add cone and volume
better than 70dB control, mono or stereo,
* Power requirements - system to choice
36V d.c. at 700 mA * Easily built in an evening
SUPERB QUALITY AND POWER
FOR SUCH VERY SMALL OUTLAY
Complete kit of parts including
transistors and X -20 manual
in sealed carton
Built and tested with £9 -' -6
X -20 manual in 7
sealed carton
£7.19.6
X -20 Power Pack
sufficient to drive
two X -20's £4 -19 -6
A UNIQUE TUNER FOR A UNIQUE AMPLIFIER
See previous pages for details of the amazing Sinclair
Micro FM Tuner /Receiver. Ideal for use with the X -20.
Full service facilities available to all Sinclair customers
SINCLAIR RADIONICS LTD. r
sinlair COMBERTON, CAMBRIDGE COMBERTON 682
www.americanradiohistory.com
Decem7er, 1965 PRACTICAL WIRELESS 727
SINCLAIR
TO BUILD GUARANTEED
SI CLAIR MICRO -6
The smallest radio
of its kind in the world
Everybody's building it
SIX -STAGE
CIRCUIT
LUXEMBOURG
COMES IN LIKE
A LOCAL
FANTASTIC RANGE
AND POWER
EASILY BUILT IN
AN EVENING
PLAYS ANYWHERE
WEIGHS LESS
THAN I oz.
flow about you ?
No transistor set has ever yet compared in its
class with the Micro -6 for size, power, performance
and design. Enthusiasts from electronic engineers
to beginners in transistor construction go on
building the Micro -6 until thousands are now in
use all over the world. Everything except the
lightweight earpiece is contained within the smart
minute white, gold and black case. With pill -size
batteries and self -contained aerial, the Micro -6
weighs under one ounce! Unique features which
make such wonderful performance possible include
bandspread over the higher frequency end of the
Amazing 6 -stage circuitry
In the Micro -6, a six stage circuit using 3 special Micro -
alloy transistors (Sinclair M.A.T.$) provides two stages
of R.F. amplification, double diode detector and high
gain 3 -stage A.F. amplifier plus A.G.C. and bandspread
over the higher frequency end of the tuning to bring
in Luxembourg like a local station. Inserting the plug of
the earpiece switches the Micro -6 ON; withdrawing
switches it OFF. Tuning is
by vernier -type dial over
the medium wave band.
Two self- contained
batteries give
about 70 hours
working life.
All parts including M.A.T.s, case, dial,
lightweight earpiece and beautifully
detailed easy -to- follow 8 page instruc-
tions come to
MALLORY MERCURY CELL
Type ZM.312 (2 required) each 1 /II.
Pack of 6 10/6.
"Transrista" Black nylon strap for
wearing Micro -6 on your wrist 7/6.
5
medium waveband for easy reception of Luxerrv-
bourg, powerful A.G.C. to counteract fading of
distant stations, and vernier type tuning. Quality
of reproduction is outstandingly good, so that you
derive real pleasure from using this fantastic set.
Order your Micro -6 now and you will quickly see
why it cannot be too highly recommended as an
intriguing design to build and a most practical
radio to use. You can build it in an evening and
when you have built your first, be certain others
are going to want one too, when they see and hear
the Micro -6.
A.G.C.
let R.F. 2nd R.F.
Amp. Amp. ej Detector -
L Ist A.F.
Amp. J2nd A.F.
Amp. 3rd A.F.
Amp.
Micro -6 builders write
"I ans highly satisfied with this kit which re-
ceives most stations on the medium wave with
remarkable volume apart from the fact that this is
a bad signal area." M. A., Sheffield G.
"My pleasure at the way it works is only exceeded by
the pleasure it gave me in building it and my own surprise
at being able to complete such miniature work satisfactorily.
I am no longer the youngster that assembled radios before
the B.B.C. was born. W. J. R., Warwick.
"Performance easily surpassed expectations. Luxembourg and
AFN were loud and clear and many continental stations could be
heard at adequate strength including Moscow. R. S., Northumberland.
"Having been a transistor fiend for the last eight years, I must say it is the finest
little set I have ever constructed. Please send one more of these marvellous
little instruments." R.K., Preston, Lancs.
FULL SERVICE FACILITIES AVAILABLE TO ALL SINCLAIR CUSTOMERS
Please send me
NAME
ADDRESS
for which I enclose Cash /Cheque /Money Order
value L s d.
GUARANTEE ORDER FORM`
Ouarant¢¢
Should you not be completely
satisfied with your purchase
when you receive it from us,
your money will be refunded
in full and at once without
question. Please quote PW.12
should you prefer to write
your order instead of cutting
out this coupon. ej
www.americanradiohistory.com
728 PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS December, 1965
AERIALS
ALL TYPES OF TV /FM AERIALS
AVAILABLE
BBC 1 dipole, 1816; 'H', 3816; 'X', 3516;
ITA 3 element, 2116; 5 el., 2919; I I el., 461 -;
Combined I x 5, 3516; 'H' x 5, 491 -; loft I x 5
compact with pole, 3616; F.M. 3 el., 491 -.
BBC II 8 el., 331.; 14 el., 3916; 20 el., 581 -.
Price includes clamps and postage.
S.A.E. for enquiries.
J. R. R. BAKER
35 St. Mark's Road, Windsor, Berkshire.
TAPE RECORDERS,
TAPES ETC.
TAPE TO DISC - New H.fgh -level
Cutters, 45 r.p.m., 21/ -. S.A.E. leaflet.
DEROY, 52 Hest Bank Lane, Lan-
caster.
SOUND RECORDINGS
A UNIQUE TAPE. Buy top brand
lin. 2,400 ft. 25/, 51in. 15/. P. and
p. 1 at 2/ -, 2 at 2/9, 3-6 at 3/6. Bar-
gains in all sizes. S.A.E. for list.
E. C. KINGSLEY & CO. LTD., 93
Tottenham Court Road, London, W.I.
EUSton 6500.
RECEIVERS & COMPONENTS
TRANSISTORS, new, Red Spot and
White Spot, 28/. per 100 (minimum
quantity either type). Post paid.
G3LMR, 113 Groby Road. Gleaneld,
Leicester.
TREASURE HUNT! Help me to find
Certain Types of Relays and Contacts
to earn spare cash. Send S.A.E. for
details. 112 Oroby Rd, Gie efleld,
Lekleater.
RADIO -TV- ELECTRONIC
COMPONENTS
BARGAIN PRICES
New
0C44. 0046. 0071, OÓ72, sOC8 m, 0C81dm,
AF117 2/6 each
MATCHED PAIR 0072 6/- each
BY 100 500m/A 8/- each
SERVICE SHEETS 3/- each
D. & p. 6d,
MAINTENOR RADIO
888 Great West Rd.. Heston, Middx.
TRANSISTORS, UNMARKED, UN-
TESTED, 40 for 10/ -, p. and p. 1 / -,
4 packete post free. Relays, thousands
of types, special catalogue free.
General catalogue of Mechanical and
Electrical Gear, Tools, etc., 5,000
items free. K. R. WHISTON (Dept.
PEW), New Mills, Stockport.
R & R RADIO & T V SERVICE
Dept. P.W.
NABEl? STREET, RAMP, LAM.
Telephone 465
SALVAGE VALVES Tested before despatch
6F18 4/8 V329 5/. PL38 8/- 20P4 6/8
6L18 4/8 10P14 5/- PL82 3/8 30P16 5/-
EF80 1/8 2OP6 8/8 U601 7/8 PCC84 4/-
E0082 8/- 30P 7/- 10F1 1/8 PY81 8/8
ECL86 8/8 6F16 6/- 20F2 5/8 U301 ß/-
30F6 6/- EB91 1/- 3NFL1 5/- 10P13 6/8
PLSB 8/. EF86 6/- PY32 6/- 20D1 8/-
PCPH 4/- 8/301,2 4/- 6U4GT 6/- 30P12 6/-
P1,81 6/- 20P3 8/- 6F1 2/8 PY88 5/-
P230 6/- 3OPL1 4/- EY86 4/-
Speakers. Ex-TV. gin. round 8 z 4ta, 8/8; Ms
round. 8/ -; post 2/ -,
Lies Output Transtormees available, Stets set
model No.
Tunes Tuners. B / -. past 2/--
Bean Cotte, Ste. Quote set model No. with an en-
quiries
&ehiset M Baasisllo Sr %eyl goods
RATES: 7/3 per line or part
thereof average lise words to line,
minimum 2 lines. Box No. I/. extra.
Advertisements must he prepaid and
addressed to Advertisement
Manager. "Practical Wireless,"
Tower House, Southampton SL.
London W.C.Y.
RECEIVERS & COMPONENTS
(continued)
VALVES REACTIVATED to as -new
condition. Receiving 3/- each, trans-
mitting 4/-. Post 6d. per valve.
Restore performance of your equip-
ment at minimum cost. Send stamp
for leaflet. G IM I IOTT, 3 Sandgate
Ave., Tilehurst, Reading, Berks.
MARCONI CANADIAN RECEIVER NO.52
Shipping
Amateur,
.0 Broad-
cast. Mag-
nificent 10-
valve re-
ceiver in
three swit-
ched wave-
bands cov-
ering 1.75-
16 Mc /s
(19 - 170
metres).
p I u s 3
valve cry-
stal cali-
brator employing dual crystal to provide marker
check at 10- 1004000 kc /s. Om RF and two IF
stages. Other refinement=: valve, HT, and Signal
check meter. Internal Sin. speaker and two H/
Phone outputs with switched control. RF -AF
Gaio, Noise Limiter, Filter, BFO, Heterodyne pitch
control, Wide and Narrow Bandwidth, Man or
AVC on CW A RT. Fast and Slow tuning with lock.
Additional OSC Tuning (piss a minus). Power
requirements HT 160v. 80mA: LT 12v 14 amps.
else 16 x 14 z 12ía. Fully tested and working
ONLY 69.19.0. Carr. 15/8 or complete with Power
supply unit suitable for 116/230v. AO maim
612.19.6. Carr. '20/,
No. 53 GROUND -STATION comprising Receiver.
Transmitter and 13v. D.C. Power Unit, 627.10.0.
Carr. 22.10.0. (Mainland only.)
WHEATSTONE BRIDGE
Centre Ze o
Galvanometer
Scaled 20.0 -20
2tin. movement.
2.5 mA. full scale
d-fiectlon, 3 stud
switch controls
0.10. 0400 ohms,
0 -Ind. Complete
In carrying case
with Instructions,
45/.. Post Si-.
TELESCOPIC AERIAL MASTS. Tubular steel
copperised, spray finish, ring cam locking on each
section provides for full or any height required.
Suitable all fixings and base locations. Bottom
section 1s /,in. diameter. 20ft. (4 section) Closed 5tt.
gin. Weight 161b. 65 / -, Carr. 5/ -, 34ft. (6 section)
Closed 8ft, gin. Weight 201b. 76/ -, Carr. 5/-,
Further height by adding 3.4ft. Whip sections 18/8.
Carr. 4/-. Special price for quantities.
WAVEMETER CLASS D
Freq. band 1,900
Ke /e. to 8,000 Kc /e.
(158 -37.5 metres)
in two ranges. 1,900
Kc /s. 4,000 Ec /e.
also 4,000 11c/s.
8,000 Kc/s. Supply
6 v. D.C. input.
Complete with twin
vstal. As new.
PRICE 62/8.
P. a P. Si..
TELEPRINTERS
CREED 78 used condition. Price from 615; Teletype
Corp., Type 14B, 617.10.0. Carr. 30/- each.
All No. 19 Set parts available.
Mussy other 5aryoim/ S.A.E. all enp.irtes.
A. J. THOMPSON (Dept P.W.)
MILLING LODGE"
OODICOTE, RITCHIN, HERTS.
Phone: CODICOTE 242
RECEIVERS & COMPONENTS
(continued)
50 TRANSISTORS, all tested, marked
and guaranteed. AF, PF, Silicon
and PNP. Unobtainable elsewhere
at this low price of 35/ -, plus p. and
p, 1 / -. D. & W. LTD., 224 West Road.
Westcliff -on -Sea, Essex.
'iHEATHKITS" can now be seen in
London and purchased on easy
terris. Free brochure. DIRECT TV
REPLACEMENTS LTD., Dept. PW7. 9,
126 Hami;ton Road, West Norwood,
S.E.27. GDPsy Hill 6166.
Guaranteed Brand New in original carton
CANADIAN MARCONI 52 RECEIVERS
Few only at 09.10.0 Carr. 20/-
MAINS POWER UNIT 02.10.0
Supplied with Outer Case, Handbook and
Circuit. Range 1,75 -16 Mc /s.
Set has Crystal Calibrator, Speaker, etc.
V.H.F. RECEIVER. PYE P.T.C. 114
65 -100 Mc¡s 12 Volt D.C. Supply
This is an I I valve double superhet receiver,
operating on one fixed frequency between
65 -100 Mc /s., crystal controlled, speaker
output using midget valves throughout.
Supplied in first class condition with tuning
data, circuit diagram and complete crystal
formula. Ideal for the four -metre band (70.2
Mc /s.) offered at only 70/ -, post 5/ -,
These well made tuning units, made for
the American 19 Tx -Rx, are housed in a
metal case, colour green or brown using
a large precision calibrated scale, are an
essential piece of equipment for the
serious Tx or Rx operator. This unit
will match an untuned wire or Whip
Aerial to almost any Short Wave
Receiver or Transmitter, exceptionally
good for Mobile Top Band use. This
American version being well noted as
far superior to any other. GUARAN-
TEED BRAND NEW, only 20/ -, Post 7/6.
Instructions supplied.
JOHN'S RADIO
OLD CO.OP WHITEHALL ROAD
DRIGHLINGTON, BRADFORD.
SPEAKER REPAIRS, cones fitted.
Satisfaction guaranteed. L. S.
REPAIRS, Pluckley, Ashford, Kent.
DIRECT TV REPLACEMENTS LTD.,
largest stockists of TV Components
in the U.K. Line Output Trans-
forme s, Frame Output Transformer,,,
Deflector Coils for most makes.
Official sole suppliers for many set
makers. Same Day Dispatch Service.
Terms C.O.D. or C.W.O. Send S.A.E.
for quotes. Day and Night Telephone
GIPsy Hill 6166 126 Hamilton Road,
West Norwood, S.E,27.
CANADIAN MARCONI 52 RECEIVERS
as per previous adverts. 010.10.0. Carriage
Paid. Handbooks 5/ -. Leaflet S.A.E.
LOUDSPEAKERS t0- 3 ohm In wood case.
Cases soiled. 25/- Carriage Paid. 19 or 22 Set
Head and Mike Sets, 10 /- Post Paid.
V.H.F. FIELD STRENGTH METERS,
100 -150 me /s. Telescopic Aerial, 2' Round 1
MA. Meter, 35/- Post Paid.
PILOT BULBS 6.5V..06 amp. 5/- doz. Post
Paid. Meters 100 MA, 20- Round, 10 /- Post
Paid. 20H 120MA. Chokes 8/6 Post Paid.
50 Amp. Relays 12 volt coil, 3/6 Post Paid.
(Carriage charges apply to England and Wales
only) Telephone: Worthing 9097
40/42 PORTLAND
ROAD. WORTHING
1
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS 729
RECEIVERS & COMPONENTS
(continued)
MIN. JACK SOCKETS, 5/- doz. Co-
axial Plugs 10 /- doz. 0071 Transistors
2/6 eacn. P. /p. 1 / -. over 10 /- post
free. B. H. GORDON ELECTRONICS
LTD., 12 Essex Rd., Stevenage, Herts.
FOR SALE
SPECIAL OFFER
GEVAERT 'TAPE, New. to_rne.i, Jq, duoit. with
stop and Leader Tapes, ' /- o, B for 60/ -.
ORUNDIO MAl 2 Transistor Pre -amps for
Tape Monitoring or Microphone Booster.. 57/6.
LIST PRICE 4 GNS.
LEE ELECTRONICS
400 Edgware Road. Paddington 6521
Send for Free liar, *fai)e at abash
IIAM:11EItI'l'E
HAYNER PATTERN BRUSH PAINT FOR
PANELS AND BOXES
* THE PATTERN IS fN THE TIN *
ALL YOU DO Is BRUSH IT ON!
21 os. tins 3/6 i gallon 35 / -s
1 pint 7/6 I gallon 68/ -
I pint 16/- ('sent by road)
Carriage: Orders no to 5l- 9d.. up to 10(. I
and over 219.
CnSoare: Blue. Olive, or Metallic Black.
Return of post service. Mon. to Fri.
From yon, component shop m direct from the
manufacture,:
FINNIGAN SPECIALITY PAINTS (PW)
Mickley Square. Stocksesid. Northumberland.
!'boor: Nihl.k,t!eld '1_ISB
240rn° ELECTRIC POWER
LTÜZ ®from 12 all CAR BATTERY
W AMERICAN DYNAMOTOR UNIT
Irpn 11t smut Walt it 15015 271wBt
Wl,) In mlvleox. roll) 10015 In1 rl)
uni,nsil ar/DC IIICnitlt Inuirmilitylus
wasteful Halo. 1,11, o1218 s scrrnlitt.
Sen/ 01e51 enclore lut 91111lelnlsl Built
µ' 'SOIxrinC ?AMDDCll, Cllnlnl,tml.
ANYWHERE
MORSE EASYE a
The famous RHYTHM RECORDED
COURSE cuts the practice time down
to an absolute minimum.
One student. aged 20. took only 13
DAYS, and another. aged 71, took
only 6 WEEKS to obtain a G.P.O
pass certificate. Ir you wish to read
Moose easily and naturally please
enclose 8d. in stamps or two inter-
national reply coupons for full
explanatory booklet
To G3OHS,
45 GREEN LANE, PURLEY, SURREY.
FANTASTIC
OFFER
HUGE IYI PORT PURCHASE
MAKES Tlll'. OFFEIt POSSIBLE
6- TRANSISTOR
RADIO
De -Luxe, Pocket Sized model with Sony
transistors, plus Hide Case, Personal
Earphone and Battery. Powerful Hl -Fl
Tone and High Sensitivity. Made to
sell at 3 times price. Brand new In
attractive presentation box and fully
g ONLY 22 -19 -6 COMPLETE
P.P. 2/9, INDUSTRIAL SUPPLIES
Brunswick St., Stockton on Tees,
Co. Durham
FOR SALE
(continued)
ELECTRIC SOLDERING -IRON
FANTASTIC
BARGAIN OFFER
Lightweight Pistol Grip handle
40 watt. 240/250v. A.C. Solid
copper bit. Detachable handle
forme cover for Mob when not in
use. With 41ft. Safety 3 -Core
flex. Indispensable for
every home handy - OVL
man. A boon to model ,
makers and a necessity 9 6
for every wireless en-
thusiast. Offered to P &
you at this new amaz- 1/-
mg price.
C. H. SERVICE, (Dept. P.W.)
Limes( 11511 Lane. Tatsnelrl. heal.
TRANSISTORS
Il- each. Red or White Spots.
27- each. XA 101, XA 102, X8103,
0A90, XAIII, XAII2, 0C430,
V10 /IS.
31- each. 0C44, 0C45, 0070,
0071, 0081, OC8ID, XAI51,
XBI04, XCIOI, XCIOIA,
OC 169, 0C200.
41- each. AFII4, AFII5, AFII6,
AF 117, 0C170, 0C171, XA 103,
XAII6, XBI02, XBI05, XCI21,
XU6I I.
Sr- each. 0C139, OC I40,
0C204, ORP60, XA70I, XA703,
GET7, GETS, GET9, XC 14 I ,
BYI00, 0A21 I.
107- each. 0C19, 0C22, 0C25,
0C26, 0C28, 0C35, 2S013.
ZENNER DIODES
4.7v. to 30v., kw. 316, 1.5w. 51 -,
7w. 61- each.
Plus many more. Send 6d. in
stamps for full list and eq. chart
B. W. CURSONS
78 BROAD STREET
CANTERBURY, KENT
WANTED
WE BUY New Valves, Second -hand
Cameras, Binoct lars Projectors,
Amplifiers, Records Car & Transistor
Radios, Components etc. Send s.a.e.
to EDDY'S (NOttm.) Ltd., 116 Alfre-
ton Road, Nottingham.
WE BUY New Valves for cash, large
or small gilantitie- old types or the
latest Send details. Quotations
by return. WALTONS WIRELESS
STORES, 15 Church Street. Wolver-
hampton.
A PROMPT CASH OFFER for your
surplus brand new Valves and
Transistors. R.H.S., Beverley House,
Mannville Terrace, Bradford 7.
WANTED
.nlinuedl
URGENTLY WANTED: New modern
Valves. Transistors, Radios, Cameras,
Tape Recorders and Tapes, Watches,
Toots, any quantity. S. N. WILLEITS,
16 New Stree-. West Bromwich,
Stalls. Tel 2392
DAMAGED AVO METERS wanted,
Models 7 and 8. Any condition. Any
quantity. HUGGETT'S LTD.. 2 -4
Pawsons Road Wed Croydon.
WANTED: Old Eddystone Short Wave
Components and Battery Sets. Box
60 P.W.
WANTED
VALVES ONLY
Must be new and boxed
Payment by return
WILLIAM CARVIS LTD.
103 North Street, Leeds 7
MISCELLANEOUS
TV
SETS CONLYRS EACH
OR 20 FOR E25
20 PALMERSTONE ROAD
EARLEY READING, BERKS.
WORKING
NOT 35 I_
-ELECTRONIC MUSIC?
Then how about making yourself an
electric organ? Constructional data
available -full circuits, drawings and
notes! It has 5 octaves. 2 manuals and
pedals with 24 stops -uses 41 valves,
With its variable attack you can play
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Write NOW for free leaflet and further
details to C. r S., 20 Maude Street,
Darlington, Durham. Send 3d. stamp.
BOOKS & PUBLICATIONS
SURPLUS HANDBOOKS
19 set Instruction Handbook 3/8 p/p 6d.
1155 Instruction Handbook 3/6, p /p. 6d.
H.R.O. Instruction Handbook 3/8, p/p Od.
39 set Instruction Handbook 3/6, p/p Od.
48 set walkie talkie Circuit A Notes 3/6, p/p 8d.
88 set walkie talkie Instruction Handbook 416.
pip lid. Frequency Meter BC221 Inetruetion
Handbook, 3/6, pip Bd. Wavemeter Clap D
Handbook Mk. I, A a Hl, 3/6, pip dd. 18 eet
Circuit Details & Notes, 3/6, pip 6d. 52 Mt
Instruction Handbook 4/6, pip 6d. 8107
Instruction Handbook 4/6, p/p 6d. R1116 /A
Circuit Diagram & Details 1/9 p/p 6d. 111284 /A
Circuit Diagram A Details 1/6 p/p Bd. R11155
Poemt Diagram A Details 1 /6. pip 6d. RF Unit
24 Circuit Diagram & Details 1 /6, pip 6d.
RF Unit 25 Circuit Diagram A Details 1/6, pip
Bd. RE Unit 28 Chant Diagram A Detail 1/8,
p/p dd. Amplifier A1134 Circuit Diagram &
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Indicators. ILdicates the value of a resistor at a
glance. Price 1 /6, pi, 6d. All mall orders to:
Instructional Handbook Supplies,
Talbot House. 28 Talbot Gardena,
Roundbay, Leads, 8.
www.americanradiohistory.com
730 PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS December, 1965
SITUATIONS VACANT
TV AND RADIO- A.M.I.E.R.E., City
and Guilds, R.T.E.B. Cert., etc., on
" Satisfaction or refund of fee "
terms. Thousands of passes. For
details of Exams, and Home- training
Courses (including practical appara-
tus, in all branches of Radio, TV
and Electronics write for 156 -page
handbook -FREE. B.I.E.T. (Dept.
242G), 29 Wright's Lane, London,
W.8.
SMITHS RADIOMOBILE
Britain's Car Radio Specialists
RADIO SERVICE ENGINEERS
These appointments are progressive and
there are prospects of advancement for
men with the right experience and
ability
Please apply te:
The Personnel Manager
S. SMITH & SONS
(RADIOMOBILE) LTD.
Goodwood Works
North Circular Road
London, N. W.9
GLAdstone 0171
A.M.I.Mech.E., A.MS.E.R.E., City and
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For details of Exams, and Courses in
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SITUATIONS VACANT
(continued)
CENTRAL ELECTRICITY
GENERATING BOARD
South Western Region
Western Division
HINKLEY POINT
NUCLEAR POWER STATION
Applications are invited for the following
position at Hinkley Point Nuclear Power
Station, near Bridgwater, Somerset.
Maintenance Craftsman
(Instruments)
Applicants should preferably have had
some practical experience in the servicing
of electronic, electrical, and telecommuni-
cation equipment.
A knowledge of Conventional Power
Station instrumentation would be an
advantage.
The conditions of service will be in
accordance with the N.J.I.C. Agreement
for the Electricity Supply Industry which
includes a basic salary of í22.6.3d. per week
on day work and í22.16.5d. on shift.
After two years service a further 8s. 6d.
per week is paid.
Applications on Form AE /6M, which may
be obtained from the Station Superin-
tendent, Hinkley Point Nuclear Power
Station, near Bridgwater, Somerset, should
be completed and returned by 4th Decem-
ber, 1965, quoting ref. P.W.
RADIO RENTALS
(U.K.) LTD
(Required)
TELEVISION
ENGINEERS,
INSTALLERS
& RIGGERS
Clean driving licence essential. Permanent position
with superannuation and sickness benefit scheme.
Three weeks holiday after qualifying period. Five
day 40 hour week.
Apply by letter or telephone our local branch or
St. Albans House, 181 The Parade, Watford. Watford
26494.
SITUATIONS VACANT
(continued)
A FULL -TIME TECHNICAL EXPERI-
ENCED SALESMAN, required for
Retail Sales. Write, giving full
details of age previous experience
and salary required, to the Manager,
HENRY'S RADIO LTD., 303 Edgware
Road, London. W.2.
RADIO AND TV Exam. and Courses
by Britain's finest Home -study School.
Coaching for Brit.I.R.E., City and
Guilds Amateur's Licence, R.T.E.B.,
P.M.O. Cert.. etc. FREE brochure
from BRITISH NATIONAL RADIO
SCHOOL, Russell Street, Reading.
SERVICE SHEETS
SERVICE SHEETS for all makes of
Radio and TV, 1925 -1965. Prices from
1/- with free fault- finding guide.
S.A.E. inquiries. Catalogue of 6.000
models 1/6. Valves, modern and
obsolete. Radio /TV Books. S.A.E.
lists. HAMILTON RADIO, Western
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SERVICE SHEETS, Radio and Tele-
vision, 41 post paid. VEST AND
EMERY, 17 Hallgarth St., Durham.
SERVICE SHEETS. Radio, TV, 5,000
models. List 1 / -. S.A.E. inquiries.
TELRAY, 11 Maudland Bank.
Preston.
SERVICE SHEETS (75,000) 4/- each.
Callers welcome. Always open. 5
South Street, Oakenshaw, Bradford.
SERVICE SHEETS, Radio and TV. by
return post, 2/6 each. S.A.E. 57
Boundstone, Hythe, Southampton.
SERVICE SHEETS
4f- ea., plus postage
We have the largest display of Ser-
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of Radios, Televisions, Tape Record-
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service.
To obtain the Service Sheet you
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From:
Name:
Address:
To: S.P. DISTRIBUTORS
44 Old Bond St., London, W.1
Please supply Service Sheets for the
following:
Make:
Model No Radio /TV
Make:
Model No Radio /TV
Make:
Model No Radio/TV
I also require list of Service Sheets
at I/6.
(please delete items not applicable)
1 enclose remittance of
MAIL ORDERS ONLY DE. PW
www.americanradiohistory.com
tp
December, 1965 PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS I
EDUCATIONAL
City and County of Bristol Education Committee
BRISTOL TECHNICAL COLLEGE
CAREERS IN RADIO AND RADAR
Marine Radio Officers
2 -year, full -time course for young
men aged 16 upwards; leading,to
Ist and 2nd Class P.M.G. Certifi-
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ance Certificate.
Conversion Course (2nd Class to
Ist Class).
R.T. Courses (for Full or Restrict.
ed Licence).
Training given on the latest types of Marine and Aircraft Equipment
in the newly equipped Laboratories at
THE SCHOOL OF MARINE RADIO AND RADAR
For details write to: THE REGISTRAR
BRISTOL TECHNICAL COLLEGE
ASHLEY DOWN, BRISTOL 7
Licensed Aircraft Radio
Engineers
2 -year, full -time course for
A.R.M.E. Licences, categories A &
B, and 6 months' courses for
Radar Rating in association with
above.
RADIO OFFICERS see the world.
Seagoing and Shore appointments.
Our many recent successes provide
additional trainee vacancies during
1966. Orants available. Day and
boarding students. Stamp for
prospectus. WIRELESS COLLEGE.
Colwyn Bay.
THE INCORPORATED PRACTI-
TIONERS IN RADIO AND ELEC
TRONICS (I.P.R.E.) LTD. Member-
ship conditions booklet 1 /, Sample
copy of I.P.R.E Official Journal 2/
post free Secretary, Dept. B., 32
Kidmore Road, Caversham, Reading,
Berks.
CITY AND GUILDS (Electrical etc
or. Satisfaction or refund of fee "
te -ms Thousands of passes For
seta C s of modern cou -ses in ail
Or inches of Ele'tr:cal Frr:neerlr,.
Electronics. Radio. TV. Automat on.
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RADIO OFFICERS' training courses.
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ICS DEPT. 541, PARKGATE ROAD,
LONDON, S.W. II
METAL WORK
METAL WORK. All types cabinets,
chassis racks etc., to your speciflca-
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LTD , Chapman St., Loughborough.
when
replying,
to
advertisements
please
mention
Practical
Wireless
2 METRES 4
The thrill,- u VHF Amateur Radio!
Complete kit. 70 -150 Mcls, costs only
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step
-by -step instruction,
Write today encaosing a stamped
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full details. Overseas enthusiasts note
we despatch to al, parts of the world -
local stamp OK for literature. "GLOBE,
KING" (Reed, precision standard
products tried and trusted by Amateurs
everywhere.
JOHNSONS (Radio)
St. Martins Gate, Worcester
PADGETTS RADIO STORE
OLD TOWN HALL
LIVERSEDGE, YORKS.
Telephone: Cleckheaton 2866
Special Otter. Brand New Boxed TV Tubes.
MW43/69, 65/ -. MW36/24, 37/6. 90 Degree
Tubes with slight glass fault 371- each.
Carriage on any tube In G.B 10/ -. Fully
Guaranteed for 12 months.
Reeialmed Tubes. 51x months' guarantee.
AW43180. 30/ -. MN 43/6, 301 -. MW43/69, 30 / ,
CRM172 301 -. CRM142, 17/ -. 12 inch tubes,
101- l7 Inch tubes perfect but without
guarantee, 17/- each. Carriage on any tube
in G.B., 101 -.
Scope tube removed from units. 007 -8,
2.51n., perfect condition, 30/ -. Post 4/6
Few JAP earpieces complete with lead and
plug, 3 or 5mm, 1/11. Post paid or 20/- per
dozen.
New Transistors, 0072, 2/-: CV425, 1Od.:
CV448 10d.: CV442. 10d.
New Modes. top grue no duds, 3/- doz.,
post paid.
New 121n. Speakers with built -In tweeter
3 or 15 ohms. 28/8. Post paid.
Perfect Speakers ex. equipment. 101n.
round 10 / -. Post 3/ -. 81n. round, 6/ -: Post
3 / -; 7 x 41n., 5i -. Post 21 -. 6 x 41n., 3/ -. Post
21 -. Six for 201 , post paid. 6ín. round, 3/ -.
Post 2 / , 20/ , Phillips Sin. Round. 5/+
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Motors Single Phase 240v. quarter R.P.,
26/ -; 1400 Revs. Fully guaranteed, ex.
washing macnines, carriage 8/6.
Sma:, Switch Y.Iotor 24v will run I rom 12 or
b volts. 101 -, post paid.
Bush (2ln. TV 24 C 13 channel TV. Complete
and tested with good tube. only wants clean-
ing, 55 / - carriage 10/ -, G.B.
VALVE LIST
Ex equipment. 8 months' guarantee
EL91 1/6 20P3 qq// PCC84 4/-
ELBO 2l- 20P4 8/6 PCL82 bi-
EL84 5/- U801 8/6 PCL85 5/-
ECC81 31- U281 5/- PL36 5/-
ECC82 3/- U282 5/ 12ÁT7 3/-
EY51 2/8 U329 b/- 6CR8 1/8
EY86 5/- KT38 6/- Rib 3/e
EBF80 4/8 6VCGT 9555/1/1:: / ARP12 1/e
ESN 90. 6133 1/6 50 for £1
ECC83 4/- 1K25 5/-
EL38 51- 6P7á 3/6 EF50 1/-
EFbI 9d. 604 Si-
6Fó 1/- FY33 81- EF80 DOS. ó/-
6F14 Si- PY80 3/
6Fó5 5/ PY81 3/- Dos 10 /-
lOC2 5/- PL38 8/8 6K7 Doz. Ì iS
ioiei ll PL81 4/-
10P13 5/- PL82 3/- 6V8 1/p
10P14 5/- PL83 3 / 18 /-
20Di 21- PY82 3/- 888 1/9
20L1 B/- PCF80 433/1/..--
/ DOL.1 /
20P.' 41- PZ30 5/. 025 5/-
AI valves po-t i; :),
96 pages of factual tabulated
data ...
"PRACTICAL WIRELESS"
RADIO & TELEVISION
REFERENCE DATA
.:ompiled ,.y 1. P. Hawker
Contains lull details of colour codes;
everyday formulae, for calculating the
values of biasing components, potential
dividers, resonance. gain. etc -; aerial
dimensions: a quick frequency -wave-
length conversion table: stations and
requencies; common symbols and
abbreviations; notes on amateur radio
and a list of call -si =n prefixes; communi-
cation receiver 1.F.s; mathematical
data including logarithm tables; wire
and cable data: battery equivalents;
valve. transistor and picture tube pin
connections, bases, ratings and equiva-
lents, Including selected CV types.
ve pages. illustrated, over 62 pages of
tables.
lac. 80. FROM ALL BOOKSELLERS
or, in case of difficulty 118.6d. by post from
GEORGE NEWNES LTD.. Tower flouse.
Southampton Street, London, W.C.2.
NEWNES
www.americanradiohistory.com
732 PRACTICAL WIRELESS December, 1965
10/14 WATT HI -FI AMPLIFIER KIT
A stylish
finished
monaural
amplifier
ith an
output of
14 watts
from
EL84's in
push - pull.
Super rep-
roduction
of both
music and
speech
with negli-
gible hum.
Separate inputs for mike and gram, allow records
and announcements to follow each other. Fully
shrouded section wound output transformer to
match 3 -150 speaker and Independent volume
controls and separate base and treble controls are
provided giving good lift and cut. Valve line-up
2 EL84's, E'Ú)83, EF88 and EZ80 rectifier. Simple
instruction booklet 1(6. (Free with parts).
19.6'.Á
All parts sold separately. ONLY £6. 8/6 P.
Also available ready built and tested complete with
standard input sockets. 88.15.0. P. & P. 8/8.
Carrying Case for above 28(8, P. & P. 7/6
SPECIAL HARVERSON OFFER ! ! !
BRAND NEW HEAVY DUTY Lean. SPEAKERS
Response 45 c /a -13 Ke /a ltin. voice coil. Available
in 3 to 15 ohms. Guaranteed full 15 watts British
rating. Heavy cast aluminium frame. These are
current production by world famons maker and as
they are offered well below list price we are not
permitted to disclose the name. LIMITED NUM-
BER ONLY. UNREPEATABLE AT 89/6 P. & P.
5/, ALSO 25 watt Guitar Model available at 86.5.0.
And 33 watt Guitar Model 88.8.0.
HIGH GAIN 4- TRANSISTOR
PRINTED CIRCUIT AMPLIFIER KIT
Typo TAI
Peak output in excess of 1} watts. All standard
British components. Built on printed circuit
panel size e x Sin- Generous she Driver and Out-
put Transformera Output transformer tapped for
3 ohm and 15 ohm speakers. Transistors (OET114)
or Bl Mollard OC81D and matched pale of 0(81 o/pa
9 volt operation. Everything supplied, wire,
battery clips, solder etc. Comprehensive easy
to follow Instructions and circuit diagram 1 /6.
(Free with Kit). All parts sold separately.
SPECIAL PRICE 45/- P. & P. 3/ -.
Also ready built and tested 52/8. P. A P. 31-.
A pair of TALI ae ideal for .stereo.
HARVERSON'S F.M. TUNER Mk. I
F.M.
tuning
head by
famous
maker.
Guar-
anteed
non -drift
Per -
meabili -
tytuning
Fre-
quency coverage
88 -150 Mc/e
Balanced diode output. Two I.F. stages and
discriminator. Attractive maroon and gold
dial (7 x 3in. glu). Self- powered using a good
quality mains transformer and valve rectifier.
Valves used: ECC85, two EF80's and EZ80
(rectifier). Fully drilled chassie. Sire of com-
pleted tuner 8 x 6 x Id in. All parts sold separately.
Set of parts if purchased at one time, 85.19.8.
plus 8/8 P. & P. and fns. Circuit diagram and in-
structions 1/6 post free. Mark D Version as above
but complete with magic eve front panel and
brackets 88.12.8. P. & P. 818.
Mark III Version as Mark I but with output stage.
(ECLB'l) and tone coutrol 87.7.0. P. & P. 8/6.
Handsome Metal Cabinets. Choice of Black or
Green. To fit Mark 1, 25/ -, P. & P. 3h. To fit
Mark 11, 17/6, P. &
SPECIAL PURCHASE TURRET TUNERS
By famous maker. Brand new and unused. Complete
with PCCS5 and PCP80 valves 34.38 Me /e I.F.
Biscuits for Channels 1 to 5 and 8 and 9. Circuit
diagram supplied. ONLY 25/- each. P. & P. 3/9.
OORLER F.M. TUNER HEAD
88 -100 Mels i0.7 Mc /e L.F. 16 / -. plus 2)- P. & P.
1E102 valve, 8/8 extra).
4 -SPEED PLAYER UNIT BARGAINS
All Brand New in Maker's Original Packing
SINGLE PLAYERS
GARRARD SP25 De Luxe 812.10,8, Carr. 5/6
B.B.R. G07 with unit mounted pick -up arm.
84.18.8, Carr. 5/6
E.M.I. with unit mounted plat -up arm.
84.9.8, Carr. 6/6
AUTO CHANGERS
LATEST B.B.R. UA25 Super Slim mono. 88.2.8
B.S.R. ÚA16, 18.19.8; N.C.R. DADS, 16.10.8
LATEST GARRARD AT5 88.8.0
Standard GARRARD Autoslim 18.10.0
GARRARD AT8....810.10.0, Carr. 8/6 on each.
All the above unite are complete with t/o mono
head and sapphire style or can be supplied with
compatible stereo head for 12/6 extra.
THE NEW HARYERSON KIT FOR THE HOME
CONSTRUCTOR
A really excellent
all purpose A.C.
mains 200 /240v.
AMPLIFIER KIT
TYPE HSL `FOUR'
8 VALVE 4 WATT
USING ECC88
ELS4, EZ80
VALVES
Special features ine-
lude: Heavy duty double -wound mams transformer
with electrostatic screen. Separate Baas, Treble
and Volume controls, giving fully variable boost
and cut with minimum insertion loss. Heavy
negative feedback loop over 2 stages ensures high
output at excellent quality with rely low distor-
tion factor. Suitable for use with guitar. micro-
phone or record player. Provision for remote
mounting et controls or direct on chasms. All
this builds onto a chassis sire only 7 4-ins wide x 4in.
deep. Overall height 41ím All components and
valves are brand new. Very olear and concise
Instructions enable even the inexperienced ama-
teur to construct with 100% eaccess. Supplied
complete with valves, output transformer (8 ohms
only), screened lead, wire, nuts, bolts, solder etc.
ago extras to Dn PRICE 79/6 P.Aé/-
Comprehensive circuit diagram, practical layout
and parts list 2 /S. (Free with kite).
QUALITY RECORD PLAYER AMPLIFIER
A top -quality record player amplifier. She
Tan. w. s 21-1n. d. z 5 }fm h. This amplifier (was
used In a 28 gn. record player) employs heavy duty
double -wound mains transformer, ECC83, BLS4,
11E80 saves. Separate base, treble and volume
controls. Complete with output transformer
matched for 3 ohm epeaker&eady built and tested
PRICE 69/6 P. & P. 4/9
ALSO AVAILABLE. Mounted on board with
output transformer and bin. speaker ready to
fit into cabinet below. PRICE 89/6, P. & P. 5/9.
QUALITY PORTABLE el /PLAYER CABINET
Uncut motor board. Will take above amplifier and
B.S.R. a GARRARD Autochanger or single
Record Player Unit. Size 18 x 14 x 851n.
PRICE 63.9.6. Carr. 7/6
e TRANSISTOR AND DIODE
SUPERHET
A first-class 2 waveband transistor superhet
Printed circuit panel (size 85 x 2/ in.). 3 pre-
aligned IF transformers. High -gain Ferrite Rod
Aerial. All First -grade transistors. Car aerial
winding. Push -pull output. All parts sup-
plied with simple instruction. All parts sold
separately. Set of parts if purchased at one time
ONLY 84.5.0. P. & P. 2/6. Circuit diagram 2/-
(free with set of parts).
35 OHM SPEAKERS
Suitable for use with atom. 'lip. Goodmans. Ideal
placement for most pocket portables 8/6, 30M.
12/8; 7 x 4in., 21/ -. P. & P. 2/- per spkr.
Portable CABINET
Sloe approx. 9} x 61 x 3 9in. Suitable for above
using 3 }In. speaker. 25 / -. P. A P. 2/6.
COIL AND TRANSFORMER SET
FOR TRANSISTOR SUPERHET
3 IF transformers one oscillator coil one driver
transformer and wotmd Ferrite aerial (med. long
and car aerial coupling) 82/6 complete post 2/ -.
6 transistor printed circuit board to match 8/6.
Post 1 / -. Circuit diagram 1/6 extra.
LATEST MODEL B.S.R. TU;I2
4 -SPEED PLAYER
AND PICK -UP
ONLY 69/6 g rf
lin. metal lturntable
Low flutter perform-
ance. 200 /230 v.
shaded pole motor
with 90 v. tap for
valve heaters. High
gain crystal pick-
up with turnover
LP /78 head complete with sapphire etylii.
TWO VALVE GRAM AMPLIFIER
ON PRINTED CIRCUIT BOARD
(17Y85, UL84). Can be used with
80 v. tap off motor. O.P. Trans.
volume and tone controL Size 6 }in.
wldes-2in
deep x
3 }In high
overall.
ONLY
89/8. P.
& P. 2/6
Mains
dropper
res. for
filaments
if required. 2/6 extra.
SPECIAL PURCHASE!
FROM LEADING
HI FI MANUFACTURERS
7 -10 watt OUTPUT TRANSFORMERS to
match pair of ECL88's in push -pull to 3 ohm
output. ONLY 11/ -. P. & P. 2/6.
7 -10 watt ULTRA LINEAR OUTPUT TRANS-
FORMERS to match pap of ECL82's in push -
pull to 3 ohm output. ONLY 15/ -, P. & P. 216.
SPECIAL MAINS TRANSFORMERS to match
either of the above. Tapped primary. Secondary
250v. 80mA half wave and 6.3v. 2 save.
ONLY 12/8. P. A P. 2/6.
NEW CARTRIDGE BARGAINS
RONETTE STEREO 106 CARTRIDGE. Stereo /LP/
78. Complete with two sapphires. Original Wt price
87/9. 01716 PRICE 24/ -, P. A P. 1 /,
ACOS 71-5 single sided crystal cartridge for Stereo
and L.P. records. Complete with diamond stylus
and universal mounting bracket List price 88.8.4.
Our price 18/8. P. A P. 1/ -.
STEREO AMPLIFIERS
Incorporating 2 &CL82's and 1 BESO heavy duty
double -wound mains transformer. Output 4 watts
per channel. Fula tone and volt me controls. Abso-
lutely complete.
BARGAIN PRICE
ä/F.19.6 P'BI6P.
SUPER DE LUXE version of above incorporating
ECL88 valves separate bass and treble controle
and full negative feedback, 8 gnu.. P. & P. 6/6.
SPECIAL GRAND NEW
TRANSISTOR BARGAINS
GET 15 (Matched Pair) 15/ -; V15/10p. 10/ -; 0071
5/ -; 0076 8/ -; AF117 7/6; ORP12 10 /6.
Bet of Mollard 8 translators 0044, 2-0045 OC81D
matched pair 0081 26 / -, ORP12 Cadmium Sulphide
Cell 10/8. EDIBWAN MAZDA
PXA101 6 /6; XA103 6/6.
R.F.I. Pack: 1- PXA102 Mixer; 2-PXA 101
I.F. Amp. (Equiv.0044 and 0045) 10/6
R.F. 2 Pack; 2- PXA101 I.F. 1- PXA102 Osc.:
1- PXA102 Mixer 12/8
L.F.6 Pack: Consisting of PXB113 Driver Matched
pair P1171 mounted complete with heat sinks
(Equiv. OC81D and OCR) 12/6
ALL TRANSISTORS POST FREE.
HARVERSON SURPLUS CO. LTD.
170 HIGH ST., MERTON, S.W.19 CHErrywood 3985
Open all day Saturday Early closing Wed. I p.m.
A few minutes ¡rom South Wimbledon Tube Station (Please write dearly)
PLEASE NOTE: P. & P. CHARGES QUOTED APPLY TO U.K. ONLY. P. & P. OVERSEAS
ORDERS CHARGED EXTRA.
SEND STAMPED ADDRESSED ENVELOPE WITH ALL ENQUIRIES
BEE
RIGHT
HAND
PAGE
FOR
MORE
ITEMS
1
y
www.americanradiohistory.com
Dec ember, 1965
3 -VALVE AUDIO AMPLIFIER
MODEL HA34 ueaiguod i a lit -Pi
..e'produrtiou oi
records A.C. Maint
operation. Ready
burn on plated
heavy gauge metal
chassis tine 741u.
w. x 4in. d. a 411u. h.
Incorporate. EtiC83
11I.84, ELBU valves.
Heavy duty (ionise-
wound mains transformer and o itr ut transtorrner
matched for 3 ohm speaker, separate Hass, Treble
and volume tvmtrols. Negative feedback tine
Output 11 watts. Front pane. can or detached
and leads ext,-nd,d for remote mounting of con-
trols The HA34 has been 'morally designed for us
and our quantity order enables a4us pto utter them
complete with knobs. valves. RA n P. A P.
etc. wired and tested MI only a/" .. u
BRAND NEW 3 OHM SPEAKERS
.. 12 /0; I/fin. 15 / -t Nin 21 / -; IOin., 25 / -:
121n., 27/6; 112in. 15 ohm, 30/ -1, 10in. x gin.. 26/ -.
E,M.I. 1311 x sin. with turn Rix ceramic magnet
42/ -; 15 chut, 45/ -. P. & P. 5in. S / -: tif and Nin.
3/6, 10 and 12íu. 8/6 per 'meeker.
QUALITY PORTABLE
TAPE RECORDER CASE
Brand new and malted. beautifully made and
expensively finished in dark grey heavy grade
renne. Satin chrome metal grille front and
chrome fittings. Speaker aperture 8 x lin,
Ovendl size 151w. x 15,1. x 71h. ins. Will take
any standard tape deck or tingle record player.
Limited number only. Worth at least £5. OCR
PRICE 49/6. I'. A P. 2/ -.
TAPE DECK
8.SR. MONARDECK. Single speed, 521n. per
tee., simple control uses 521n. spools, 06.15.0 plus
7/0 Carr. and Inc. Tapes extra.
BARGAIN OFFER CORNER
MAINS TRANSFORMERS
Semi- shrouded drop thro' type. Prl. 200.
230, 240y. Bee. 220v. 5 wave at 70rnA and 0.3v. at
8 amp. c /t.
Stack size 3 x 24 x 141n.
PRICE 11 I P. A P. 3/-
PRECISION 6JMINUTE DELAY ACTION SWITCH
Clockwork actuated. Made by Smiths. Separate
switching actions at intervals up to 0 mine.
Each switch action designed for current loading
up to 15 amps at 250 volts. Suitable for photo-
graphic timer, sequence witching operations, etc.
eta Brand new and unused unite offered at
fraction of their true value. OUR PRICE ONLY
10/- each. P. P. 1/0 (8 or more poet tree). Special
quotations for quantity.
HEAVY DUTY NON -INDUCTIVE D/P MICRO
SWITCH. Conservatively rated 10 amps at 250v.
Standard one -hole fixing. Body else 12 z f z lino.
deep Ino. terminals 8/- each. P. A P. 1/- (6 or
more poet tree).
NEON A.O. MAINS INDICATOR. For panel
mounting,
Inc. tterminal.uWhite size
pse with Zeno giving brighter
light. For mains 200/250v. 2/6 each. P.P. 6d.
10 or more poet free).
VYNAER AND REPINE SPEAKER AND CABI-
NET FABRICS Approx. 04in. wide. Usually
86/- yard. OUR PRICE 18 /S per Yard length.
P. 4 P. 2/6 (min, one yd.) S.A.E. for samples.
ACOS CRYSTAL DES, High imp. For desk
or hand use. High sensitivity 18/6. P. A P. 1 /8.
TSL CRYSTAL STICK MIKE. Listed at 42/ -,
OUR PRICE 18 /8, P. & P. 1 /0.
T.C.C. SUPPRESSOR CONDENSERS. 250v. A.C.
.005 t .005 z .1. to tubular can fm. long r
fin. die. '2 for 3 / -, poet tree.
TRANSISTOR DRIVER and 0/P TRANSFORM-
R (Tapped 3 ohm and ohm
1
4 suitable Translators giving approx. 1 watt
output 26 /-, P. & P. 2/8.
2-GANG .0006 TUNING CONDENSERS. 2I1n. h. x
2fm. d. x 12115. w. with built-in trimmer. 4 /e.
P. & P. 2/ ,
MATCHED PAIR OF SI WATT TRANSISTOR
DRIVER AND OUTPUT TRANSFORMERS.
Stack size 15 x 15 x Iln. Output trans. tapped for
3 and 15 ohm output, 10 /- pair. P. A P. 3/ -.
BRAND NEW PLESSEY. 12v. 4 -pin non-eyrie.
vibrators. Type 12 1.48D. ONLY S/S. P. A P.
1/8 each.
TWIN TELESCOPIC AERIAL. Composing two
3- section heavily chromed rode. Closed 121n. each
extending to 32in. Completely adjustable
from vertical to horizontal. Supplied complete
with universal mounting bracket, coax lead and
plug. Suitable for F.M. or TV 12/6. P. A P. 2/ ,
4-WAY NON -TANGLE TELEPHONE CABLE
Latest spring back cull type, extends 121n. to Aft.
Complete with rubber bushes, 4/8 each P.AP. 1/6,
1 Harverson Surplus Co. Ltd.
PRACTICAL WIRELESS 733
AMPLIFIERS SPEAKERS
NORTHCOURT "FIVE" AMPLIFIER IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIillll
Suitable for guit-
ars, grams and
radios.The 5 watt
output amplifier
incorporates
separate volume,
treble and bass
controls.
Two jack
socket inputs
are fitted. Twin
speakers give
exceptionally
realistic repro-
duction and are
built into an attractive cabinet. Size:
Length I lain. Height Hain. Depth 5Zin.
finished in mottled grey with the front
covered in Vynair. Mains Voltage 200/250,
50 K/c. Ideal for home use with any guitar.
Retail E9.17.6.
1
EQUIPMENT CABINETS
OF DISTINCTION
P.A. EXTENSION SPEAKER
Suitable for radio
and record play-
ers. Size: Length
10in. Height Tin.
Depth Sin.Fitted
in durable indus-
trial finished
wood cabinet,
attractively fin-
ished in mottled
grey. Speaker
front covered in Vynair. Price 29/9 Retail.
As above fitted with volume control. 35/9
Retail.
P.A. TWIN EXTENSION SPEAKER
Suitable for all radio and record players
(incorporating two speakers 6 x 4in.). Size:
Length 12ín. Height 71in. Depth 51in.
Fitted in durable industrial finished wood
cabinet, attractively finished in mottled
grey. Speaker front covered in - Vynair.
Price 39/6 Retail. As above fitted with
volume control, 43/6 Retail.
FULLY SHROUDED UPRIGHT
TRANSFORMERS
350-0 -350 100mA 6.3v. 4A C.T. 0-5v. at 3
amp. 29/6 Retail.
300-0 -300 IOOmA 6.3v. 4A C.T. 0.5v. at 3
amp. 29/6 Retail.
250-0-250 IOOmA 6.3v. 4A G.T. 0 -5v. at 3
amp. 29/6 Retail.
All products guaranteed 12 months. Trade
supplied. For name of nearest stockist and
lull accessory brochure, write to:
NORTHCOURT (Electrical Bfd,)
LIMITED
Transformer and Coil Manufacturers
Dept. P.W. SOUTH PARK MILLS,
PUDSEY, Yorks.
N.S. KITS
No Soldering - No Drilling
High performance Medium Wave Radio
you can really build yourself. Unique
kits that really work with add-on kits
to increase power and range.
Kit No. NS.I VM, 47/6
Postage & Packing. 3/3
Full details sent on receipt of stamped
addressed envelope.
Circuit diagrams and details send 2(6.
(deductible on order).
G. A. TAYLOR LTD.
21 HYDE ROAD, DENTON
MANCHESTER
Imperial
Illustrated in this advertisement are
two fine cabinets from the Lewis
Radio Range.
These Cabinets are lust Two et
really extensive range.
Each one carefully made by British
Craftsmen and soundly constructed
from the best materials available.
Fill in coupon below to obtain FREE
catalogue showing this wonderful
range of cabineta.
¿ THE NEW LEWIS
v RADIO CATALOGUE
Designed to
Cabinet.
The New Lewis Radio Cabinet Cata-
logue -the most comprehensive ever
prepared. Sent absolutely FRRRI
Please send your PitRE 24 puoi cabinet
catalogue.
ansiar cour 011010e u:
NAME
ADDRESS
(Dept. 125)
Capitals please
s 100 Chase Side. Southgate, London
N.14. lei Palmers Green 3733/9666
L e
www.americanradiohistory.com
734 PRACTICAL WIRELESS December, 1965
MEnts
MORE PRACTICAL HOUSEHOLDER
KNOW -HOW FOR
ENTHUSIASTS
Extend your technical and constructional range
with these famous "Practical" magazines ....
each bringing you the expert, up- to- the -minute
guidance you tFind every month in the pages of
PRACTICAL WIRELESS.
riTel PRACTICAL
1 HOUSEHOLDER
Britain's first and foremost
do -it- yourself magazine,
covering 101 jobs about the
home. Monthly 1/6.
PRACTICAL
MOTORIST
Shows motorists how to do
their own repairs, mainten-
ance and overhaul, and save
pounds on garage costs.
MONTHLY 2/ ,
SPECIAL EEE THIS ISSUE
+ ea tEaca£s Ist )àa fL 8t7f8
ü?ats &fa ïs h*ee i[.){3
Ft (!shB8i8t Wafer Egcg
ilEttii tr a
PRACTICAL
MOTORIST
F E '+ `
guide in
Winter
Motoring
Slept 1htaiilEi'.>:.
PRACTICAL TELEVISION
The television enthusiasts' own magazine, packed with the
latest technical data. MONTHLY 2/ -.
PRACTICAL ELECTRONICS
All you want to know about electronics -new ideas -new
methods -latest constructional know -how. MONTHLY 26.
PLACE A REGULAR ORDER WITH YOUR NEWSAGENT
www.americanradiohistory.com
December, 1965 PRACTICAL WIRELESS
RADIO CLEARANCE LTD.
27 TOTTENHAM COURT ROAD, LONDON W.I. Telephone: MUSeum 9188
Bulk enquiries invited. The oldest component specialists in the trade. Est. 35 yrs.
LOUDSPEAKER BARGAINS STILL AVAILABLE
Enormous purchases of Brand New and Guaranteed Plessey loudspeakers
enable us to offer these units at THE LOWEST PRICES EVER! Don't miss this
golden opportunity to obtain a first -grade permanent- magnet LOUDSPEAKER
off the production line at LESS THAN THE MANUFACTURER'S COST! Head
carefully the prepared list below and choose just the right speaker for the Job -
COMPARE THE PRICES ANYWHERE! SELLING FAST -STOCKS CHANGING
RAPIDLY.
Sign
fl. inrlw
Gauss
w. New
/mired.
to
Maw Pries
Site Gauss
in. in.
inches lined imps
.isms Pried
Size Gauss
incises frees
/raped.
on.
ohms Price
21
2f
2f
3 38 31
5 x 3
5 x 3
s x 3
5 x 3
6 x 4
8 x 4
ö x 4
7000
7000
7000
7000
8600
7000
7000
6500
6000
7000
9000
7000
9000
9600
8500
9600
9500
35 60 80
6
35 0 16
3
86 3 3 3
8
3
36
9/6
8/8 8/-
19/-
9/8
10/- 9/6
12 /- 8/-
8/8 9 10 /-
121-
si
4
4
4
4
7 x 38
7 x 38
7 x 31
7 x 4
7 x 4
7 x 4
7 x 4
7000
9500
6000
7000
7500
9000
9500
9500
7000
9600
9500
9500
9500
10000
12000
3 35
50
35 35 5 60 36 15
9 3 8
3
80
3
3
10/8
10/6
19 /8
11/- 9/0
11/8
11 /6
12 /-
9/8
10 /8
110
11 /-
12 /8
12/6
16/6
3
8
8
10
10 10
4 5
5
5
5 68
x 21
x 21
x 2J
x 6
x 8
x 6
9500
7000
7500
9500
9500
8500
7000
6000
7000
9500
11000
11000
11000
25
3 15 26 3
3
5
3
3
6
25
11 /6
8/8 9/-
10/8
12/8
10/8
11/-
9/6 9/-
10/-
22/6
U/8
23/8
ALLOW 2/Ó each Speaker for postage and packing and handling charge and please
specify the exact requirements -the nearest available will be sent.
SELECTED BARGAINS
Beautifully geared AM /FM 2 -gang Condensers. 4/6: AM /FM IFT'S 465 ke /s and 10.7 Mc /s
plMdytitn aRecorder krif Amplifiers
ready to switch 79/8: tecell eters R3/2D-D3-2-1-Y, 2/each
DIODES -0A79 OA90 CG46H, GD10, 2/- each.
TRANSISTORS: OC45 4/6, PXA101, 3/9, AF115, 4/6. Sub min. Germanium diode 1 /3.
Ml diode 8d. each. Silicon diodes. 400 p.1.v.. 330mA. 2/6 each, please send STAMPED
and ADDRESSED envelope with any enquiry. We regret no catalogue -our stocks
move too quickly! Kindly make provision for additional postage and package charge
to avoid delay. Terms: Cash With Order or C.O.D. on Orders over 10 / -.
HAM ANTENNA
CONSTRUCTION PROJECTS
by Stanley 24/ -- P. & P. 1/-
How to Listen to the World, new ed.
by Johansen. 20/-. P. & P. 1/ -.
Amateur Radio CirculteiBook by R.S.G.B.
7/8. P. & P. 1 / -.
Electronics Data Handbook by Clifford.
16/ -. P. & P. 1 / -.
Pick Ups, the Key to HI -FI by Walton.
10 / -. P. & P. 11 -.
Guide to Amateur Radio new ed. by
R.S.G.B. 5H. P. &
Radio Amateurs Examination Manual
new ed. by R.S.G.B. 5 /-. P. & P. 8d.
Radio Amateurs Handbook by A.R.R.I.
40/ -. P. & P. 3/ -.
Where possible 24 hours service guaranteed
UNIVERSAL BOOK CO.
12 Little Newport Street, London, W.C.2
(adjoining Lisle Street)
£2
POST FREE
On your OWN TRANSISTOR PORTABLE!
* No Plugs -No Connections' Just. place Dewtron
Wave Trap near radio! Boosts 'Pirate' and
distant stations, reduces 'fading'.
* Estesi. Battery Life!
* Use io oar or caravan Without Aerial I
British-made. Supplied with PP3 bolt. (life several
months) and instructions. Money refund guarantee.
D.E.W. LTD., Dept. P.W., Ringwood Road,
FEENDOWN, Dorset
o
LISTEN
4.1
J è AND ENJOY THE
À WORLD'S RADIO AMATEUR
3, AND BROADCAST STATIONS WITH G
- THE GREATEST OF EASE 1!! 2
We HAVE SOLVED your aerial problem for
WORLD -WIDE RECEPTION -NO MATTER
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World Expert Radio Amateur WIBB
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his massive 520' YEE aerial 70' high.
ZL4GA, who is probably NEW ZEA-
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has scrapped his outstanding 300' 45'
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CONTINENTS on the JOYSTICK in
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"CQ" the Rodio Amateur's journal
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YOU CAN BE THE PROUD OWNER OF THE
WORLD'S MOST VERSATILE 8 COMPACT
"JOYSTICK" COMPLETE RECEIVING SYSTEM
FOR AS LITTLE AS
15.5.0 (DX- MAGNET system), 66.6.0
(Standard system), 17.7.6 (De -luxe system)
including carriage and packing.
Money Back if not Delighted
Not convinced? Then send for
brochure and showers of testimonials
to:-
PARTRIDGE ELECTRONICS LTD
(Dept. P.W.)
CAISTER HOUSE, PROSPECT ROAD
BROADSTAIRS, KENT
I.R.C. Exhibition Stand No. 26
735
TEST METERS
,
.,
ow
a, t J .
20,000 O.P.V. MODEL TP 5S. R ads voltage up to
1,000 D.C. at 20,000 ohms per volt and A.C. at
10.000 O.P.V.; D.C. Current to 500mÁ; Resistance
to 10 Mega.; Capacitance to 0.1µF; Decibels from
-20 to +3R. Size 341n. x 6 }in. x 11in.. 05.19.8.
2,000 O.P.V. MODEL TP 10. Reads A.C. and D.C.
Volts up to 1,000; D.C. Current to 600mA;
Resistance to 1 Meg.; Capacitance to 1i/.F;
Decibels from -20 to +36; Output Jack for
Audio Measurements. Size 38 x 6 x 11in..
03.19.6.
30,000 OHMS PER VOLT MODEL 500. Reads
voltages up to 1,000 D.C. at 30,000 ohms per volt
and A.C. at 15,000 O.P.V.; D.C. current to 12
amps. Resistance to 60 Mega.; Decibels from -20
to +56; incorporates internal buzzer for audible
warning of direct shorts and blocking condenser
for A.F. output measurements. Size 3' /n, x6sl
x ills., g6.19.0.
TRANSISTORISED TEST EQUIPMENT. Fully
guaranteed, brand new. By NOMBREX: 150
Kc /a. -360 Me /a. Signal Generator, 69.10.0.
Resistance- Capacitance Bridge. 08.6.0. 1 -16 volts
D.C. Power Supply, 18.10.0. Audio Generator
10 /100,000 c /a. 616.15.0. Inductance Bridge.
118.0.0.
SPECIAL OFFER OP AMERICAN VALVE VOLT-
METERS. 11 Mega., Input. 6 D.C. Voltage
ranges to 1.000. 5 A.C. voltage ranges to 1000
6 Resistance range to 1.000 Megohms. tin.
200 Wcroamp. meter. For 110 /250 voila A.C.
operation. With taut predo and operating instrue.
[tons. Manufactured by RCA and Electronic
Designs. ONLY 87.19.8 (Poet etc. 8/6).
LINEAR AMPLIFIERS. LG34, 4 watts, else SO x
40 x 38in. high. 95.6.0. JASA 6 watts, ize
7 x 7 x Sim high, 65.19.8. Protective cover 12/9.
L5/66 5 watts stereophonic. sate 101 x 8 x 6m.,
612.12.0, cover with carrying handles, 96/ -.
"Diatonic" 10 watts ID -Fi Ultra Linear Push -pull
size 9 x 7 x 641n. high, 112.12.0. Cover with
carrying handles, 19/8. L1/10 10 watts Hi -Fl
Ultra Linear size 9 x 7 x Sin. high, 915.15.0.
Cover with carrying handles. 19/8. "Conehord"
30 watts lit-Fi Ultra Linear size 121 x 9 o 71in.
high. 216.16.0. Cover with carrying handles. 25/-,
L50 50 watts Hi -F1 Ultra Linear, size 14 x 10 x
Bin. high, 628.2.0. Cover with carrying handles,
82/8. All amplifiers for normal. A.C. mains, and
ex stock. Details on request.
"Tripletone" Convertible Amplifier, Oise 10 x
3 x 411n. high. 4 watts output matched for 2 -3
ohms, OR 2 amplllen can be coupled together for
STEREO. 46.19.8 each.
"Triplefone" P.M. Tuner, else 11 x 6 x Sin. high.
Coverage 94.104 Mc /s. 113.19.6 (onpowered), or
115.14.8 (self- powered). Details oo request.
MICROPHONES. Crystal Types. Guitar, 12/6.
Desk, with built -10 stand 15/ -. Aces 89/1. Stick
and Table Stand 82/6. Super Stick, with heavy
Desk Stand 49/8. Moving Coil Types. Stick with
heavy Desk Stand, 69/5. "Slimllne" Stick, 60K
impedance, with switch 75/ -. Omni- directional
chrome plated die -east frame. 50K with switch.
99/6.
HARRIS ELECTRONICS
(London) LTD.
138 GRAY'S INN ROAD,
LONDON, W,C.1
Telephone: TL- Hiram. 7937
Please include carriage roar on d LL items.
Trading hones 9 a.m. -6 p.m., Monday- Friday.
Closed Saturday. We are 2 mina. from High Hol-
born (Chancery Lane Station) and 5 mint. by bus
from King's Cross.
www.americanradiohistory.com
736 PRACTICAL WIRELESS December, 1965
44A WESTBOURNE GROVE
LONDON W2
TeL: PARK 6841/2/8
rL I AI:1tO SERVICES LTD.
Please send all correspondence and Mali Orders to the Read Office
When sending cash with order, please include 2/6 in 2 for postage and handling
MINIMUM CHARGE 116. No C.O.D. orders accepted
Retail Shop.
85 TOTTENHAM COURT ROAD
LONDON W1
Tel.: LANgham 8408 Q
Open al' day Saturday
0A2 6//-
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125 6/-
185 4%
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1282.7 7/-
12807 4/-
1281056T 9/-
12807 4/-
128117 4/-
12827 4/-
128K7 5/-
128Q70T8/8
128E7 5/-
1284 2/8
13D1 5/-
13133 ó/-
14Q7 10 /-
19AQ6 5/-
1903 25/-
1906 15/-
2001 14/-
20P3 18 /-
2004 14/-
2005 12 /-
25A60 5/-
2505 10 /-
25L6OT ß/-
25Z40 8/-
25Zá 10 /-
25Z80T 11 /-
2807 7/-
2901 80/-
3006 7/-
30C1 7/8
30016 11 /-
30017 13/-
30018 11 /-
3006 11 /-
30FL1 18/8
30FL12 12/
ECS3
First Quality Fully Guaranteed EC86
EC88
EC90
8091
2092
ECC31
ECC40
BRAND EEC0070
ELECTRONIC VALVES ECC82
ECC83
30E1,14 12/-
30L1 6/6
30L15 12/8
30L17 14/-
30812 10/-
30819 14/-
3081.1 12/-
30PL13 12/-
30PL14 12/-
3001.15 12/-
35A5 11/-
3505 8/8
3505 12/-
35L60T 7/-
35W4 6/-
35Z3 10/-
35Z40 4/-
35Z40T 8/6
35Z60T 8/-
42 6/-
43I0 8/-
50A5 12/-
50135 7/-
5005 6/6
501.60T 6/6
50Y60T10/-
7501 18/8
78 6/-
78 6%-
A1 26%-
852.2 8/8
85A3 6/8
9001 12/-
100TH 60/-
150132 10/-
15004 7/8
220P2. 7/-
202B 80/-
41613 200/-
715A 80/-
715B 60/-
807 9/-
813 70/-
815 40/-
829B 80/-
866A 14/-
884 15/-
931A 60/-
954 5/-
955 8/-
956 2/-
958A 4/-
959 8/-
991 7-
1267 20%-
1616 6/-
1619 5/-
2050 12/6
5517 8/-
5642 18/-
5654 8/-
5670WA12/-
5672 7/-
80084
- 71.qi 7/- A'/.1 9/- E1x85
5750 12/- A'Z11 8/- 80086
5787 10/- AZ12 9/- 80088
5814A 101- 2.231 9/- E0091
5840 10/- AZ41 7/-
5845 80/- CBL1 15/-
5847 80/- CBL31 15/-
5963 10/- 01.33 9/-
5965 5/- CY31 7/-
5993 12/- D41 6/-
5998 15/- DA30 10/-
6005 7/8 DA41 40/-
6021 12/- DA091 4/8
6058 7/- D AF92 8/-
6059 18/- DA096 '/-
6060 5/- D090 8/-
6072 16/- DF64 5/-
6079 7/6 DP96 7/-
8095 7/8 DF97 11/-
6100 10/- 131163 8/-
6101 7/- D1177 5/6
6111 12/- DX32 8/-
6130 80/- DK40 11/-
6132 12/- DK91 6/.
6135 10/- DK92 9/-
6136 9/- DK98 8/8
8140 80/- DL63 8/-
6146 27/6 DL88 10/-
6189 38/- DL91 6/-
6186 10/- DL92 6/-
8197 86/- DL93 4/-
6202 8/- DL94 8/-
6211 4/6 DL95 6/6
6336 80/- DL98 7/8
6350 4/- DM70 6/8
6483 7/- DM160 10/-
6550 80/- DY30 7/-
6922 14/- DY86 8/-
6989 46/- DY87 9/-
7044 10/- E89CC 20/-
7586 22/6 E88C0 14/-
7895 22/6 E90CC 12/-
8013A 26/- E9113 8/-
9001 4/- E92CC 7/-
9002 5/8 218000 8/-
9003 9/- E1800 15/-
A1820 20/- BAN 8/-
A1894 20/- RABC80 7/-
A2087 17/8 EAC91 4/-
A2134 8/- 8AF42 9/6
A2226 18/- EB34 1/6
A2293 18/- 8841 6/-
AC/HL/DD EB91 8/-
8/- 8E021 7/8
AC/P4 4/- 8E033 7/-
AC/TH110/- EBC41 8/6
AC2/HL 9/- EBC81 6/6
AC6/PEN EB090 4/6
10/- EBC91 8/-
AC5/PEN/ EBF2 12/-
DD 8/- RBF80 7/6
A08/PEN EBF83 9/-
e/- EBF89 7/-
A118 e/- EBLl 14/-
ARP3 8/- EBL21 11/-
A11012 8/6 EBL31 18/-
10/- E11:3:. 8/-
121- 11M71 12/6
12/- EM80 7/-
2/8 EM81 7/8
5/- EM84 8/-
8/8 EM87 7/-
5/- EN31 10/-
10/- EN91 8/-
15/- 2N92 8/-
4/- EY51 8/-
5/8 EY70 10/-
8/- EY81 8/-
8/8 EY84 7/6
7/- EY86 7/8
EY87 8/-
EY88 10/-
EY91 8/-
EZ35 5/6
Ey.40 7/6
Ey.41 8/-
E7.80 5/8
E7.81 5/8
EZ90 4/-
FW4/500 7/-
FW4/8008/8
11010/4B 20/-
0T1C 10/-
0T3 15/-
01150 26/-
61231 5/-
OZ32 10/-
OZ34 10/-
10/-
8/8
ECC189 12/-
ECF80 8/-
ECF82 7/6
ECF86 11/-
801121 10/-
BCH4'2 9/8
801181 6/8
ECH83 7/8
ECL80 7/8
E01,82 7/8
ECL83 9/8
E01.84 12/-
801.86 9/8
8836 5/-
EF37A 8/-
EF39 5/8
EF40 9/8
EF41 8/6
1.042 8/-
EF50 2/-
E154 8/-
8055 8/-
8080 6/8
2085 8/6
2086 8/-
EF89 5/8
EF91 4/-
8F'92 2/-
8E94 8/-
8095 6/8
EF98 18/8
EF183 8/-
80184 8/-
80804 81/-
80060 10/-
EH90 7/6
EKSZ 8/-
EL2 8/-
EL5 10/-
EL32 8/-
E3.35 5/-
2126 9/-
21.37 17/6
81.28 17/8
81,41 9/6
EL42 9/-
EL50 8/-
EL81 9/8
E1,83 8/-
21.34 5/-
21.85 8/-
21.86 8/-
EL90 e/-
EL91 2/6
EL95 6/-
81280 22/-
81.821 8/-
EM4 10/-
85181 6/-
EM34 18/-
HABC80 8/-
HL2K 8/-
HL28DD 6/.
HUI
111.92
H DD/S
1122 16!-
KT'1 6/-
%T80 20/-
KT82 8/-
%T390 6/-
KT41 7/8
KT44 6/-
KT45 16/-
KT83 8/-
1CT88 18/.
%T88 418/-
KTW62 7/-
KTZ41 8/-
L02 7/-
MH4 6/-
MH41 9/-
MU 6/-
MB/PEN 8/-
MBPENT 10/-
N78 16/-
N8P1 2b/-
N8P2 22/-
02012 12/-
0E060 10/-
PABC80 7/8
PC86 18/-
PC88 12/-
PC97 9/6
PC805 12/-
PCC84 8/8
P0085 8/-
P0088 18/-
P0089 18/8
PC0189 12/-
PC'F80 '/81 111233 81-
P0002 8/- T112321 7/-
PCF84 8/-
PCF86 9/-
00087 18/-
PCF600 11/-
P00801 11/-
PCF802 11/-
800805 11/-
PCF806 18/-
PCL80 12/-
PCL81 9/-
801.62 8/-
001.83 8/6
001.84 8/6
PCL86 9/8
PCL88 9/6
P01.801 12/-
PEN46 7/-
PEN46DD
PEN48 8%-
PEN220A
P8N88810/-
PEN384 7/-
PEN453DD
10/8
PENA4 7/6
PENDD
4020 7/8
PFL20017/8
PL88 10/-
PL38 18/-
P1.81 8/.
P1.82 7/6
PL83 7/8
PL94 7/-
P1.802 14/-
P1b00 16/-
0E33 9/6
PY80 8/-
PY81 8/8
PY82 6/8
0E83 7/-
PY88 8/6
PY800 8/8
PY8o1 8/8
P126 10/-
02.90 10/-
QP26 6/-
QQV /. QQV08-10
QQV08-A
100/-
Q892/10 8/6
Q896/10 6/8
Q8108/46
Q8160/16MU 8/-
QII37 16/-
QV04-7 10/-
217 8/-
218 7/6
ßL18 10 /-
8130 12/6
814 6/-
8141 6/-
ßP42 8/-
8061 4/.
BU2160A 10-
T41 12/8
TP25 5/-
TT15 85/-
TT21 85/-
12,40 40/-
U12/14 8/-
U17 5/-
U18/20 /-
U19 80/-
U22 8/-
U25 11/-
U28 11/-
U78 4/-
U191 11/6
16261 12/6
(2281 13/-
U282 14/-
U301 12/-
17408 7/-
U801 18/-
UABC80 5/6
17.4042 9/-
171341 11/-
1713041 8/-
UBC81 8/-
UBF80 7/-
UBF89 7/8
UBL21 11/-
UC92 6/-
UCC84 10/-
UCC86 7/-
UCF80 10/-
UCH21 9/8
UCH42 9/8
UCH43 8/-
UCH81 7/-
16CL83 8/6
UC1.83 10/-
00143 12/8
UF41 9/-
UF42 9/-
UF43 8/-
UF80 8/-
UF85 8/-
UF88 11/-
UF89 7/8
UL41 9/-
16184 6/6
UM4 10/-
UM80 7/-
17176 8/-
UU7 8/-
i7U8 18/-
U09 7/-
UY1N 9/-
IIY21 9/-
ÚY41 6/9
UY82 9/8
UY86 8/-
VP28 8/6
VP41 6/-
VP210 6/-
VU89 8/-
Yt7111 7/8
VU120 10/-
W21 6/-
W81M 8/-
185 5/8
168 8/-
176M 7/6
178 20/-
179 20/-
181M 18/-
1012 7/8
1C16 4/6
Z700U 4/-
Z729 8/-
Z759 88/-
TRANSISTORS
0023 17/8 0078 8/- 28002 20 /-
0024 22/6 00780 6/- 28004 15/-
0025 12 /- 008151 7/- 28006 20 /-
0026 8/- 0001DM 7/- AC128 8/-
0028 17/6 0083 6/- ÁF114 9/-
0029 17/6 00139 12 /- AF115 7/-
0035 15 /- 00140 18 /- AF116 8/-
0036 1/- 00141 25/- ÁF117 6/-
0042 7/8 00170 7/- 2.0118 17/6
0044 8/- 00171 8/- CXT1 8/-
0045 5/- 00200 9/6 OET114 6/8
0070 5/- 00202 15/- 0ET115 8/8
0011 5/- 00204 17/8 O E T 11812/-
0072 8/- 00205 20 /- 0ET875 9/-
0072 11 /- 00208 22 /8 0ET88010/-
0075 8/- 2N410 8/6 MAT101 8/6
0078 6/- 216412 8/8 MAT121 8/8
0077 8/- 267697 17/8 T1166 0/-
Bab of 3.2x410 and one 216412 9/-
Inman( FULL WAVE POWER
RECTIFIERS, 100 P.LV.
1B26K10, a amps, 26 / -i 11340 %10
4 amps, 80/ -; 1B1ß05110, 10 amp, 85/-
GERMANIUM DIODES
OAS 4/8 OA81
02.6 4/- 02.85
OA10 8/- 0.486
0470 2/- 02.90
02.73 1/8 02.91
OA79 2/8 02.95
2/-
S/- 8/8
2/3
3/-
004E 2/-
0010E 1/8
0012E 2/-
0EX23 1/6
O8X44 1/8
0EX64 2/-
=NEB DIODES
280mW 5%
0A2200 (4.7 V) 10/-; OA'Z201 (5.1 v) 9/8
02.2202 (5.6 v) 8/-; 02.2203 (6.2 vi 7/-
0A2204 (6.8 vi 8/8; OAZ205 17.5 v) 8/-
02.2206 (8.2 y) 8/-; 02.%.207 (9.1 TI 9/6
BBOmW 15%
OAZ208 (4.3 v) 8/-; 02.Z210 (6.2 v)
OAZ211 (7.6 r) 6/8; 02.2212 (9.1 v) 7/8
LOW. t.35V
VR425 (4.25 vi 8/8; VR476 (4.76 y) 8/8
VR675 (5.75 v) 8/8
2.26W, tBV VR7B (7.0 v) 8/0
L86W, f.BV
VR10A (10.0 0) 8/-; vR112. (11.0 y)
CATHODE RAY TUBES
Suitable for Oscilloscope Use
5GP1, as recommended for P.B. Oscilloscope.
BHT 1000- 1500V, 6.3V Htre., .bin. dia. screen 50/.
400A, BHT 1000V, P.D.A. 4000V; 6.3V
344n. din. Cat face screen _
Y02139A, BHT 500V, 8.3 Mrs.. 801.
P. dla tseree7 /8 per. tube. -
HEADPHONES No. 10 ASSEMBLY
Moving OeIl PHONES ee with moving coil Hand
Microphone fitted with press-to-talk switch -
Rubber earpade. Cord terminated with army
type 6 -point moulded connector. low impedance.
Brand new 2p /- e-
Small quantity available of second hand anent-
bites, °hacked, in perfect order .- -, 8/9 sa,
F. A P. S/S Per eel. O
PHOTCEL 0813
am
Camel= Antimony, side-on window. HT 160V
senelGelty 160gÁ : Lumen .. 5/- P.P. 3/4
FERRITE ROD AEEIAL9
Omer PW /FR1 for Transistor Hallos 8/0
Weyrad R2.2W for Transistor Radice,
comprising car aerial coil -, ,. 12/6
Packing and postage 9d.
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December, 1965 PRACTICAL WIRELESS iii
PRACTICAL
WIRELESS blueprints
Send (preferably) a postal order to cover the cost of the Blueprint (stamps over 6d. unacceptable) to
PRACTICAL WIRELESS, Blueprint Dept., George Newnes, Ltd., Tower House, Southampton Street,
London W.C.2.
DOUBLE -FEATURE BLUEPRINTS
The Strand Amplifier ..
The PW Signal Generator
The Savoy VHF Tuner ...
The Mayfair Pre -amplifier
:::}
The Berkeley Loudspeaker Enclosure (
The Luxembourg Tuner ... ...f
The PW Troubadour ...
The PW Everest Tuner
The PW Britannic Two
The PW Mercury Six ...
Beginner's Short Wave Two ...
S.W. Listener's Guide ... ...
Beginner's 10 -watt Transmitter
Transmitting and Aerial Data...
PW "Sixteen" Multirange Meter
Test Meter Applications Chart
... }
:::}
:::}
:::}
.._}
The Celeste 7- transistor Portable Radio }
The Spinette Record Player ...
Transistor Radio Mains Unit ... ...} 7 Mas Transceiver ...
sr-
51-
5 1-
7,6
61-
sr-
sr-
51-
5f-
SINGLE -FEATURE BLUEPRINTS
The Tutor
The Citizen
The PW Pocket Superhet
The PW 35 -watt Guitar Amplifier ...
The Mini -amp
The PT Multimeter ...
The Autocrat Car Radio
The Beginner's Short Wave Superhet
The Empire 7 Three -band Receiver ...
Electronic Hawaiian Guitar ...
PLEASE NOTE that we can supply no blueprints other than those shown in the above list. Nor are
we able to supply service sheets for commercial radio, TV or audio equipment.
QUERY SERVICE
The PW Query Service is designed primarily to
answer queries on articles published in the magazine
and to deal with problems which cannot easily be
solved by reference to standard text books. In order
to prevent unnecessary disappointment, prospective
users of the service should note that:
(a) We cannot undertake to design equipment or
to supply wiring diagrams or circuits, to individual
requirements.
(b) We cannot undertake to supply detailed
information for converting war surplus equipment,
or to supply circuitry.
(c) It is usually impossible to supply information on
imported domestic equipment owing to the lack of
details available.
(d) We regret we are unable to answer technical
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(e) It helps us if queries are clear and concise.
(f) We cannot guarantee to answer any query
not accompanied by the current query coupon
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QUERY COUPON
This coupon is available until 9th December, 1965
and must accompany all queries in accordance with
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PRACTICAL WIRELESS, DECEMBER, 1965
Published on the 7th of each month by Gl;ORGE NEWNES LIMITED, Tower House. Southampton Street. London. W.C.2, and printed
in England by WATMOUGHS LI.MITED. Idle, Bradford; and London. Sole Agents for Australia and New Zealand GORDON & GOTCH
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www.americanradiohistory.com
iv PRACTICAL WIRELESS
MW LW POCKET SUPERHET RADIO
TO BUILD
-
- * 6- transistor plus diode.
` ¿_ * Push -pull speaker output.
* Easy printed circuit.
* Slow geared tuning.
* Full MED and long waves. NEW ! "GLOBEMASTER"
* Moulded cabinet 5 x 3 x I }in. *SHORT WAVES
1 * MEDIUM AND i
P.P. 21- (Battery 2'6, Phone 51 -) LONG WAVES
TOTAL COST 85/- Amazing sensitivity and The only FULLY tunable 3-
TO BUILD selectivity. I Waveband Radio available to
the Home Constructor
TWO WAVEBAND ALL TRANSISTOR' Printed circuit. I watt output.
CAR RADIO TO ASSEMBLE Geared tuner. Car aerial
socket with special circuits.
.
.
Push -button unit. 6- transistor
TOTAL COST £0196 high gain superhet design.
TO BUILD Size 11 x 71 x 31 in. Case
P.P. 316. fabric covered with chromed
front and fittings. All parts
* Supplied as factory built assemblies -lust interconnect, sold separately and TOTAL COST £8.19.6 P.P.
* 6- transistor push -pall design. fully guaranteed TO BUILD 316.
* Push- button wavechange -full tuning range. * 'CONVAIR" as previously advertised. Two Waveband
* Size 7 x 4 x 2 in. -fits any car -chromed front dial. Portable to Build, still available. Total Cost £7.19.6. P.P. 2'6.
* Full superhet circuit
* Units available separately.
* Guaranteed high performance and quality.
December, 1965
PROVED and TESTED DESIGNS
FULL AFTER SALES SERVICE AND GUARANTEE
UNBEATABLE FOR PERFORMANCE AND VALUE
* DETAILED LEAFLETS FREE ON REQUEST *
I IO WATT AND 20 WATT AMPLIFIERS I
TWO AND FOUR TRACK PORTABLE I ALL TRANSISTOR PRE -BUILT
TAPE RECORDERS TO ASSEMBLE AND TESTED UNITS
Prebuilt equipment -6 valves -
Collaro studio decks -portable
cabinets -8 x 5 in. speakers.
Complete recording and playback.
* Two track deck 10 gns. P.P. 51 -. °
Amplifier i I gns. P.P. 316.
Cabinet with speaker, 5 gns. P.P. 3'b. MSNiYBIYfse
or SPECIAL PRICE £26 spouse 40 c;s
P.P. 816 TWO TRACK to 20 kc:s.
* Four Track deck £13.19.6. P.P. 5' -. Amplifier 12 gns. P.P. 316. 100 mV sensi-
Cabinet and speaker 5 gns. P.P. 316. tivity.
11
AMPLIFIERS
10 watts RMS
music power
output. 20
watts peak.
6- transistor
designs. Re-
or SPECIAL PRICE £30 P.P. 816 FOUR TRACK Unit I. For
1215 ohm
# VHF FM TUNER TO BUILD
* 5- transistors, 4- diodes.
* Printed circuit superhet.
j6 * Tuning range 87 to 105 Mc's.
* RF stage and double tuned
IFT'S -9 volt 9 mA oper-
ated.
* All parts sold separately.
* Output up to I volt.
* Size 4 x 34 x 2} in.
P.P. 216 (complete with front
TOTAL COST£6.19.6 panel)
TO BUILD * Cabinet Assembly 201- extra.
c
S WATT AND I; WATT
PACKAGE AMPLIFIERS
* 6- transistor push -pull printed
circuit designs.
Peak output 10 watt and 3 watt.
Size only 2} x 2 x 11 in.
5 watt, 18 volt; I} watt, 9 12 volt.
Output for 3 to 5 ohm speakers.
7 mV into 1 Kohm. 30 c,s to 16 kc's.
*
-d *
. *
\/ *
BUILT I WATT 65/_ P.P6 5 WATT 79/6 P.1P.
NEW PREAMPLIFIER for use with If or 5 watt Amplifiers.
6 switched inputs, separate treble vol. bass controls. Price
built with Front Panel, 7916, P.P.216.
NEW FM POCKET RECEIVER KIT £5. 19. 6.
SINCLAIR. Micro -6, 59'6; X10 Kit. £5.19.6; X10 built,
£6.19.6; X20 Kit, £7.19.6; X20 built, 0.19.6.
HENRY'S RADIO LTD. open Mon. to Sat. 9 -6
303 EDGWARE RD., LONDON W2 Thurs. 1 p.m.
PADdmgton 1008 9 Open all day Saturday
Let us quote for Parts for your circuit.
Send a list for quick reply.
r
\s
Units I and 2
speakers, 40 volt supply. PRICE £3. 1 9.6 P.P.
2,6
Unit 2. For 3 to 5 ohms. BUILT
4 volt. £5.10.0 P.P.
BUILT 216
(Mains units Mono 5916 Stereo 6916)
* PREAMPLIFIERS -MONO AND STEREO VERSIONS.
8 inputs, I} mV to - - - -- - - --
300 m V at I K to -
500 Kohm. Response
30 es to 20 kc's
Complete range of
controls.
Unit 3. Mono full
function preamplifier.
Size 9} x 2f x 2in.
SlltflfA IP BII - -BASS -FILttP VGIUMF I
Unit 3
PRICE £5.10.0 P.P.
(Brown: Gold front panel. 816). BUILT 21-
Unit 4. Simplified version of Unit 3. Price built 651 -. P.P. 116.
Unit 5. Stereo preamp
Size 9 x 31 PRICE 10 P.P. (Brown Gold
x lá in. BUILT '1p 6
7' 316. panel 1216).
LOW NOISE -LOW DISTORTION QUALITY
DESIGNS -Enables complete Mono or Stereo equipment to be
assembled at a fraction of the cost of a commercial comparable
design. Simple to interconnect, outstanding quality.
Idler for use with two power amplifiers.
VHF FM TUNER TO ASSEMBLE
* Supplied as prebuilt and
aligned units plus metal
work just interconnect.
* 88 to 108 Mc s. FM tuning.
* 100 mV to 100 Kohm
output.
* 6- transistor printed circuit.
Superhet design.
* Size 94 x 34 x 4 in.
TOTAL COST 12.1 7.6 (All units available separately).
TO BUILD P.P. 216
COMPONENT CATALOGUE
Fully detailed and illustrated
catalogue. Now 96 pages. All
types of components and
equipment at competitive
prices. Price 216 post paid.
FREE NEW 12 Page
CATALOGUE, S00 Tran-
sistors and Devices, Heat
Sinks, 1000 Crystals, 800
Valves, etc., etc. Lower
Prices. More Types. Ask
for Your FREE Copy.
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