EF36 PW 1965 12
User Manual: EF36
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PRACTICAL
i RELESS
2r-
DECEMBER 1965
24-PAGE
POCKET GUIDE
AERIAL DATA
HALFWAVE AERIALS
MULTIBAND AERIALS
TRANSMISSION
LINE CATA
LONG WIRES
AER ALS
FOR
TV
www.americanradiohistory.com
PRACTICAL
AÇO
NOMBREX
LL
SOLDERING INSTRUMENTS
AND EQUIPMENT
1965
December,
WIRELESS
INSTRUMENTATION
TRANSISTORISED AUDIO GENERATOR
Model 63 LI7.I.9
** Laboratory
Direct Calibration. *
Specification
Si
10 C s to 100 Kc s.
ìe and square output.
DESIGNED FOR
THE AMATEUR'S
RADIO STATION
**
**
Also available:
ILLUSTRATED
List No.
70 e"
BIT
IN
PROTECTIVE
SHIELD
List No. 68
INDUCTANCE BRIDGE
POWER SUPPLY UNIT
C.R. BRIDGE 62
E18. 6.9
66
E6.14.6
E8.11.9
61
...
£9.I6.9
R.F. SIGNAL GENERATOR 27 ...
All prices include Battery. Post and Packing.
Prompt delivery
Trade and Export
enquiries invited
S.A.E. for Technical
Leaflets
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
for catalogue apply direct
to:-
Sales and Service Dept.
ADCOLA PRODUCTS LTD.,
ADCOLA HOUSE,
GAUDEN ROAD, LONDON, S.W.4
Telephones
MACaulay 4272 & 3101
Telegrams
SOLJOINT LONDON SW4
plastic covers. The
maximum capacitance per
section ranges from 12, 18 or 24 pF for FM types to
420 pF for AM types.
12/6
Type 00 subminiature twin capacitor at
I tType OFM two -gang for FM at
14tA Type OPC for printed circuit mounting at
Type OG2 with internal reduction gearing at 16f1
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
lit bvs
air
e In
MOST MOLLARD
MAZDA COSSOR.
EMITRON. EMI SCOPE, BRIMAR.
FERRANTITYPES
PROCESSED
IN
OUR OWN
FACTORY
GUARANTEE
125
urtMonths
12in.
14in.
15 -17in.
19in.
21 in.
23in.
0p122q
£2.10.0
£3. 5.0
£3. 5.0
£3.15.0
£3.15.0
LATEST GARRARD
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, automatically playing up to 10 records, 18.19.0.
Model 2,000- Automatic record changer 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
TYPES
KW 31/74
£3.10.0 £3.15.0
£4. 5.0 MW 36/24
£4.15.0
£4. 5.0
CRM 172
£5.15.0 MW
43/64
£5.15.0 £6.0.0
-
user-offers automatic playing, with
pusher -platform, and many other
features, 019.19.0. LAB80 -An outstanding 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 50Automatic 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 inputs, 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
nórmally
£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 8/8
£8.19.0
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 conversations, Ideas, letters etc. whilst
Unveiling or
MEMO CALL,
£8.10.0
2/6 om
TELEPHONE AMPLIFIER.
"Desk
Companion ". A larger model complete with pen and holder etc. Fully
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 BKBGT 5/3 1487
14/61EBC41
8/3 EZ41
5/91R19
96
1A7GT 9/6 8825
8/8 19AQ5 7/9 EB581 5/9 EZ80
5/9I8P41
2/3
1C5GT
7/6 8L1
9/8 20D1
6/- SP81
819 EBF80
7/8 EZ81
IH5GT 8/9 61.6
7/6 20F2
9/6 EBF89 7/9 FC4
8/- 241
8/9
1N5GT 8/9 6L8G
8/8 20L1
16/- EBL21 9/9 GZ32
7/0 TDD4
7/7/9 20P1
7/8 8L18
5/6 61,19
12/8 20P3
4/- 6LD20 7/9 20P4
8/6 25A80
e/- 6P25
9/- 6P28
9/9 25L6GT
4/- 25Z4G
5/- 6Q7G
5R40Y 8/- 6Q7GT 8/- 30E5
184
2D21
3A9
3A5
3D8
3Q4
5II40
MULTI- METERS.
TK.20.A.
8
Ranges AC/DC/Current/Res. Aff 6
(stance 0 -100K, moving coil. X9.7 {I
EP.10.K. 10,000 OPV, High quality.
15
Ranges AC /DC /Current /Resist.ance, Accuracy
%.
5Y3G
EP.20.K. 20,000 OPV, more
rive version of EP.10.
6A70
13
£3.19.6
e
5Y3GT
5Z4
5Z40
5Z4GT
8/SOL2
(USG
fí4.19.6
8AK5
8AQ7
10 Meg.
£6.19.
V
6
V
OAVB
tepee,
£9.19.6
EP.30.K. 30,000 OPV, 10 Ranges,
including Resistance to
EP.50.K, Professional Quality, 22
Ranges, AC/DC/Volts/Currrent/Response /Decibel, /CapaolPEST EQUIPMENT. IT1 -1 Transistorised Signal Injector, complete with
Transistor Oscillator with Indicator
Lamp,
Detachable Test
Probe and instructions.
35/-
BATB
BAIIB
OSAS
55E6
8608G
BBHB
BBJB
6BR7
6BW8
awn
854
655
IDEAL FOR ANY RECORDER. 656
PRICES SLASHED. GUARANTEED 859
APPROX.
PRICE.
I
WORLD 8CD8G
FAMOUS MAHR BY ENORMOUS BDB
8E1
PURCHASE.
*
TAPE
*
6F80
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, substandard, jointed or cheap imports.
Try one and prove It for yourself
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/t
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
tion.
z 1212 /rain. Magnificent reproduc-
A pleasure to look at.
"An
aristocrat In its class ". 1.2 month
guarantee against faulty Manufacture.
Genuine retad price
7 Gns.
QUALITY PORTABLE
TAPE RECORDER
228.7.6.
GUARANTEED 3 MONTHS
BY RETURN OF POST
VALVE IN VALVES
NEW
Mouths
£2 . 0.0 dui . 0.0
Autochangers, etc
Wpi
1800OPrlce
641
-
HIGHEST QUALITYCOMPARE OUR PRICES
SATISFACTION GUARANTEED
All
WIRELESS
Unrepeatable,
6E13
6F14
6E15
8E28
615G
6150T
876
8J7G
63707
6118GT
6K7
6K7G
6K7GT
6K8
6H8G
9/- U14
9/6 EBL31 19/8 HVR2
9/9 KT33C 3/9 U18
7/6
4/- KT36 14/- U22
8/9
9/- ECC34 9/- KT44
6/- U24
12 /8
8/9 025
7/9 ECC40 8/9 KT45
8/3
7/- E5581 4/9 KT81
8/0 026
e/- E5C82 4/9 KT73
5/9 U35
126
5/9 80FL1
4/- 83A7
9/8 ECC83 5/9 KT66 12/- 050
4/9 30L15 8/9 E5584
4/8 6507
7/8 KT78
8/6 U107 12/6
5/- 30P4
4/- 68K7
9/8 ECC85
8/- KT88 17/6 0191
9/- 8SL7GT 5/6 30P12
7/- ECC68 9/8 KTW81 5/9 0281
8/8
7/- 6SN7GT 4/6 30PL1 9/3 ECF80 8/- KTW83 5/- 0282 18 /5/9 35C5
9/8 6SQ7
818 ECF82
8/3 KTZ63 7/- 0301 12/8
7/-,U329
9/- 6D40T 8/- 35L6GT 8/- ECH21 11/6 MU14
8/6
7/9 BVBG
4/6 35W4
8/- ECH35 7/8 N37
10/6 U801
19/7/6 MGT 8/- 35Z4GT 5/8 ECH42 8/6 N78
13/- UABC80 7/4/8 50L6GT 8/6 ECH81 7/- N108
9/3 8%4
13/- UAF42 7/9
5/- 6%50
5/- 80
5/- ECRU 8/8 PC86
10)- 0B41
8/8
5/- 8%5GT 5/6 18511T 19/6 ECL80 6/6 PC97
7/6!OBC41
7/8
7/- 7B6
9/- 185BTA19/6 ECL82 8/- PCC84 8/6 UBC81 6/6/- 7E7
5/6 807(A)
5/- ECL83 10/6 PCC85
8/6 UBF80 7/9
5/6 705
7/8 807E
4/9 ECL86 10/3 PCC88 11/9 UBF89 7/6
5/6 7C8
7I8 813
49/- EF36
3/- PCC89 8/8 UBL21 9/8
15/- 7H7
5/- 888A 12/6 EF39
4/6 PCCI89 13/6 0CC85 7/8
8/9 854
3/6 EF40 11/- PCF80
5/- 787
6/9 UCF80 8/6
5/- 7Y4
4/6 955
2/3 EF41
8/- PCF82 6/- UCH21 9/8
8/8 1051
9/- 956
2/- EF54
3/3 PCF89 12/- IICH42 7/3
8/9 1052
14/8 9001
3/6 EF80
3/6 PCF88
7/6 OCH81 7/9
5/- 10F1
4/9 9002
4/9 EF85
8/- PCL82 7/9 0CLS2 8/2/3 lOLD1114/8 9003
5/8 KEN
7/6 PCL83
9/- 0CL63 10/9/6 ATP4
5/8 10P18
2/8 EF89
6/9 PC1.84 7/3 0F41
8/8
5/8 10P14
9/8 AZ31
6/- EF91
8/- PCL85 7/6 UF42
4/9
11/- 128E7 7/- B38
9l8 EF92
8/- PCL88 10/9 UF60
6/3
17/- 12AH8 9/- CBL31 19/- EF183 9/9 PERKS 3/9 UF85
7/6
8/- 12AT6
9/- EF184 9/6 PEN45 8/6IIF89
5/9
6/6 CL33
4/9 12AT7 4/9 C231
7/8 EL32
3/9 PEN48 4/8 01.41
7/6
3/6 12AU6 9/- DAF91 4/8 EL33
6/6 PL33
8/8IIL44 14/4/3 12AU7 4/9 DAF98 7/3 E1,34 11/6 PL38 J 9/8 1T1,48
8/3
12AV8
EL35
PL38
9/8
8/8 DF91
3/8/17/e 0L84
7/9/812A%7 6/- DF92
3/- EL38 12/8 PL81
7/9IIR10 7/8
6/6 12BA8 7/- DF98
7/8 EL41
8/- PLBS
8/8'111a80
9/6
3/- 12BE6 8/6 DK91
5/6 EL42
7/9 PL88
6/eIIII6
8/9
4/3 1213H7 8/9 DK9S
7/- EL84
8/6 PL84
7/8
11 /2I6 12E1
17/6 DK96
7/3 EM34
8/8 P231
8/- IIIIB
9/8
4/9 12170T 8/- DL92
5/- E1280
7/9 PY32 10/- U221
7/8 12K70T 4/- DL94
6/6 EM81
6/9 PY80
6/6 11Y41
6/6/- 12K8
9/9 DL98
7/3 E5184
8/9 PY81
5/9 IIY85
5/5/9 12K8GT 9/6 EABC80 6/6 EM85
8/6 PY82
5/O VR105
5/1/. 12Q7GT 5/- EAF42 3/8 EY51
7/6 "88
5/9
vai50
7/9
4/6 125417 8/3 EB41
5/- E286
7/3 PY88
9/7/9
8/8 128%7 2/9 EB91
2/- E288
8/8 PY800 6/3 %98
5l- 128Q7 7/6 EBC33 4/9 EZ40
6/8 PISO
9/8 Z88
8/6
11/- EC52
17/- ECCS2
CONNECTING WIRE
A/m
Y
Y.V.C. Bright Colours. Five
5ít. coila only.
MAINS
TRANSFORMERS
TRANSISTORS
Excellent Quality Guaranteed Upright mounting 250- 0-250v.
66tnA. 6.3v.. 3A (80mÁ 12/6)
Ditto set-in-shrouded.
e.1
.7
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
CO -A%,
/L`
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 Prot, long ,p., switch, eta
V
CONDENSERS- 25 mixed Electrolytic,
4/6
GUARANTEED TOP QUALITY
Huge reduction, Red Spot
standard LF type now only
t6
/
RS
2/-
Mallard Matched Output
Kite 0081D and 2-0081 1
R.F. Bata 0544, OC45 (2) 1
2/6
2/6
White Spot
3
transistors.
ÁF114
AF115
AF116
AF117
ÁF127
0526
0C36
8/-
0044
0545
0072
7/8
7/8
7/-
9/8
12/8
14/-05171
OCR
0581D
0552
0C170
8/6
5/8
5/8
5/6
5/8
5/6
6/5/8
GERMANIUM DIODES
portable and tramletorieed. A most Fabulous quality and reproduction of Many popular sizes. List
General Purpose miniature detector
for the desk leaving both hands free music. 6 transistor, Ilin. and 3Iin. Value 15.
Our price
A.V.C. eta.
to deal with papers, £3.10.0 speeds. Output 500mW into high
8d.
or 8/6 doz.
etc., etc.
2/8 PP
quality speaker. Ingenious single
Gold Bonded
highest quality
RESISTORS 6/6
56 WATT GUITAR SPEAKERS. control knob.
Fast forward and 100
IndividuaOy tested.
Very heavy coned 121e., cast chassis. rewind. Battery level and record. Excellent. sizes l -3 watt.
9/8 doz.
There Y nothing to touch R for level meter. Fast load. Precision 100 CONDENSERS
9/6
power handling and quality at the capstan drive with dynamic earpiece
SILICON RECTIFIERS
Miniature Ceramic and Silver Mica
price.
monitor recording. Radio recording Condensers,
Guaranteed performance.
Top
3pF to 5,000pF. LIST
Plus ti /- pap. £4.19.0 leads. Outside speaker facilities. The
Makes.
Tested 250v. working.
VALUE
OVER
25.
RINATONE 10- TRANSISTOR,
All most outstanding portable in the
if
100mÁ
250rA
wave set, complete with telescopic country. Size 819
x 3i o Olin.
25
(3 for 9/8131
TAG STRIPS 4/(3 for 19/8) 7/6
aerial, earphone, leathercase, medium Genuine normal /,e
price of 35 gm. 2, 4, 9, 8-way eta. Unused.
alas. superb performance. Not to be Unrepeatable.
12 month guarantee
LOUDSPEAKERS, 30 Tog Makro
eenlu.ed with `heap
All spares available. With I
100
HI
STABS
9/6
04i, 7/6
..C., amazing value. £10.19.0 tape, tape reel, mike, etc. 9Gns. 1% to 5 °;, 1íM 0 to 5 m O.
5ti.4fn.
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
10/-
1/-
8/6
TECHNICAL TRADING CO.
350/352 FRATTON RD..;PORTSMOUTH
www.americanradiohistory.com
,
Tel. 22034
EXCLUSIVE TO YOU
CONCORD'S TERRIFIC RANGE
!
"SKYSCRAPER"
-
Take it anywhere
it's featherweightl ein.
X 35m. z llin. Band spread Tuning, Vernier Dial. Miniature
Valve Circuits, Plug -in
BULK PURCHASE
ENABLES US TO
MAKE THIS FANOFFER
TASTIC
WITH
BACK
MONEY
I
I
GUARANTEE
The "SAN REMO"
1
.. so timed that
It
brings the voices of
star
entertainers
matically to BfeuOr hyome, 111%
vocalists dra-
and
28,6
O N LY
n
eintc
1 }m.
IO TRANSISTOR PERFORMANCE
COME EVENTUALLY! THE
COMMUPERSONAL
NICATIONS RECEIVER. Highly sensitive.
,short
-waves reception including
World -wide
news in English and countless other broadcasts from RUSSIA. AMERICA. etc., etc.
IT HAD TO
TRANSISTOR
POCKET RADIOS
-AND
December, 1965
WIRELESS
PRACTICAL
642
2
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.
ONLY
55I.
Celle, Own Rod Aerial,
etc. 50% of production
to be exported. Anyone 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.
POST
-
TRANSISTOR RADIO KITS
SOLD
IN
STORES AT
DEPARTMENT
316
LIQUIDATION PURCHASE 500 ONLY
Save £3.0.6.
Made to sell at 54 gns.
Latest camera style radio. Big-Set tone
from tone-chamber moving coil speaker.
new device plucks in Station after Station
including Luxembourg, Caroline, etc.
187577 metres!
Fantastic coverage
Expensive looking finish, simulated
35.8.0.
-
OUR
PRICE
37/6
leather,
P. & P.
batt. +3 /8 P.
4)' z
and
black
24" x 1}".7
chromium.
Size
semi-conductors. 55/- +218
& P. Refund ff not delighted.
3/6
d
Extra
Well-known brand Trarufetar Radio Kits -YOU
SAVE 23.10.8. Covering all medium /long wave with
DON'T WALKJUST TALK ! !
-
-
TILE OLDER CHH.DREN
no soldering -only
BUILD THEM!
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,
EVEN
DISPENSER
BABY ALARM
5211
196
LIGHTER
&
LIMITED QUANTITY SAVE 83.13.1
Robustly made, brand new2
ONLY
current models. You get
separate, fully transistorised
intercommunicating sets
each can speak or listen to
the other complete with BO ft. connecting wire. Fixed in a flash. Ends babytocrying worries. Ideal for Workshop
House. Siokroom, hundred of uses!
Hangs on wall or stands up. Our absurd
extra. Post, etc.
price 52/11, battery 2/6 not
8 gus. value!
3/7. Money refunded if
ANYONE
CAN BUILD
IN 2 -3 HOURS
CAR CIGARETTE
INTERCOM
OUTFIT
NEW RADIO
VOLKSRADIO
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.
High Class Stores sell at
£2.4.6
8 pis.
-- save
Top quality chromium.
Car cigarette Lighter
-Dispenser. Fixed in a icy
-
18'6
8 pins 1/
750 only.
}
P.
P. (etate
r812i.).
FABULOUS
ST. TROPEZ MK.
MAKE S DIFFERENT
TRANSISTOR RADIOS
6
The Sensational Pocket Radio
v
_
FOR
i
per
,
"4e0 -iv
®
NO
EXPER-
IENCE
-tEucatí
eda
hour
running
cost.
in one
ample
or two hours using our
A.R.C. plan. 26/- (P. & P. 2/6
extra). Case extra Parts can be bought separately.
NEC -
NoSASoldering.
Only 8 con-
radiooto work.
you get
A.B.C. Plans, Cabinet,
Earphone,
(alone
17/6).
Loudspeaker
Condensers,
4 Semi-conductors, Coils.
Resistors, Tuner. Switch. Screws. etc.
EVERYTHING! Loud Clear
YES
reception.
English
ss H.M
Educational Authorities.
pl
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/
SEND
RADIO
plus 3/6 post etc.
OB 0
This fantastic offer will amaze you
ST.
-the beautifully compact 1/in.
TROPEZ, measuring 4} x 3 z
bedroom,
in
ceives
perfectly
receives
all
medium
over
office or gardenwaves including Luxembourg. Un-
ANld.
YONE can assemble it
...op
-
(
Just look,
-
Read what lust a 15w of our satisfied customers my
R.C. of Harringay writes Received with
Very pleased. Working
thanks Skyroma
well.
...
...
I would
B.M. of Harrogate writes
If was a real bargain.
like to thank you
given it
L.S. of London W.8 writes
a good try out and I am very pleased with
the results.
delighted
S.B. of Somerset writes
glad if you could send
with this radio
one mere.
T.F. of Stevenage writes ...1 would just
like to say how pleased my son is with this
...
...
...
...
radio.
CONCORD ELECTRONICS
LTD. (DEPT. P.W.27)
9
"...
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 instructions and plan have obviously been very carefully thought out so that even the most dim
" Direct from
can follow them
Manufacturers to You. Send 19/6
plus 2/6 post, etc.
PARTS AVAILABLE SEPARATELY
writes:
Pressing Button delivers ready -lit
Tahoe
Cigarette into your hand!
10 elgareaa-King size or any size!
As lilted to luxury ears. Safe. foolproof. 41 x 4 x lilt. Lifetime
sot worth
Refund
ONLY
...
AMAZING CIGARETTE
RADIO
ONLY
186
of
Yes, a perfectly ordinary packet
but watch your friends'
cigarettes!
in
astonishment on hearing itandfetch
clear!
station after station, loud
-
-yet cleverly
Still hold. 1^ Cigarettesfully
conceals highly sensitive, tiny transistorbattery).
ised circuit (Including
it In under
Even a young boy can assemble
2 hours. No soldering. No experience
to make.
necessary. Only 18 connections
Ideal for taking to work with you. From
D. B. of
our bulging testimonial file, Mr.
I have fitted
Huddersfield, writes: ".working
wonder the parts in and tt is
odPaseLCnuctors.
A.B.C. Plans. ttc. ONY
18/6 plus 2/6 post etc. SEPARATELY
PARTS AVAILABLE
WESTERN ROAD, HOVE, SUSSEX
December, 1965
PRACTICAL
WIRELESS
643
R. .7: C,
MAIL ORDERS TO: R.S.C. MAINS TRANSFO RMERS (FULLY GUARANTEED)
54 WELLINGTON
Interleaved and Impregnated. Prim- MIDGET MAINS TRANS 21 x 21 x 211n.
STREET, LEEDS I
aries 200.230 -250 v. 50 ch. Screened.
250v. 60mA. 63v. 2a, 13/9
SHROUDED DROP THROUGH 250 -0-250v. 60mA. 6.3v. Sa, 14/9
Terms: C.W.O. or C.O.D. No C.O.D. TOP
/50-0-250v
NmA, 2.3v. 2a, 0- 5 -6.3v. 2a 17/9 OUTPUT TRANSFORMERS
under LI. Postage 2/9 extra under L2. 350-0-350v
SOmA. 6.3v. 2a, 0- 5-6.3v. 2a 21/9 Standard Pentode 5,0000 to 3f)
.. 5/9
4/6 extra under £5. Trade Supplied. 250-0-250v 100mA, 6.3v. 2a, 6.3v. la .. 21/9 Standard Pentode 7,0000 to 30
5/9
S.A.E. with all enquiries please.
250-0-250v 100mA. 6.3v. 9.5a, C.T.
19/9 Push -Pull 8 watts, EL84, or 6V6 to 30
2500-250v
100mA,
6.3v.
05
-6.3v.
8a
..
..
28/9 or matched tc 150
9/9
PERSO NALSHOPPERSWELCOME 300- 0-300v 130mÁ, 6.3 v. 4a.
4a, 6.3v.la, for
Push -Pull 10-12 watts to match 6V6 or
AT ANY OF THE BRANCHES
510 Amplifier
..
35/9 EL84 to 3-5-8 to 150
.. 19/9
BELOW. OPEN ALL DAY SATUR- 300-Muliard
0-300v 100mA. 6.3v. 4a, 05.6.3v. 3a 28/9 Following types fora and 150 speakers
DAY.
350-0-350v 100mA. 6.3v. 4a, 0- 5-6.3v. 3a 28/9 Push -Pull 10-12 watts. 6V6 or EL84 .. 18/9
350- 0-350v
150mA. 6.3v. 4a, 0-5-6.3v. 3a 37/9 Push -Pull 15 -18 watts, 6L6. KT66
.. 22/9
10 No rth ParaWd
FULLY
SHROUDED
UPRIGHT Push -Pull Mollard 510 Ultra Linear .. 29/9
BRADFORD
(Half-day
ed)e.. 250-0-250v
60mA, 6.3v. 2a. 05 -6.3v. 2a
Push -Pull 20 watts, sectionally wound
Tel. 25349
Midget type 21 x 3 x 3f n.
18/9 IL. KT66, EL39 etc.
..
.. 49/9
14 Lower
.
Castle Street
Wednesday)
BRISTOL Tel: -day
22904.
(Half
30/31 Gt. Western
Arcade, opp. Snow
Hill Station. CENtral 1279. No half-day
Osmaston Rd., The Spot
DERBV26
(Half -day Wed.) Tel: 41361
BIRMINGHAM
Wynd°Half-dayy
DARLINGTON
Wednesday) Tel: 68043
EDINBURGH
GLASGOW
133
Street.
Leith
d
Argyle Street,
Tel: CITy 4158
(No half-day).
SI
Savile Street
HULL Thursday) Tel: 20505 (Half- wt
High Street (HalfLEICESTER 32
day Thurs.) Tel: 56420
326
(Mecca)
LEEDS (County
No
) Tel.: 228252
A"`ß
100mA. 6.3v. 4a, 0- 5-6.3V, 3a 29/9 SMOOTHING CHOKES
100mA, 6.3v. 4a, 5v. 3a
.. 29/9 60mA. 10H 4000 4/11. 100mA, 10H. 2000
8/9
130mA, 6.3v. 4a. C.T. 6.3v.
80mA. 10H 3500 5/9. 150mA, 10H. 2500 11/9
la, for Milliard Amplifier
.
36/9
TRANSFORMERS
350- 0-350v 100mA, 6.3v. 4a, 0- 5-6.3v. 3a 29/9 CHARGER
with 200.230 -250v. 50 c/s Primaries:
350 -0-350v
150mA. 6.3v. 4a. 0-5-6.3v. 3a 38/9 All-15v.
lia, 12/9; 0- 9-15v. 2a. 14/9: 0- 9-15v.
425-0-425v 200mA, 6.3v. 4a, C.T. 5v. 3a 57/9 J-9
425- 0-425v 200m A. (6.3v. 40 Twice), 5v. 3a 59/9 3a, 16/9; 0- 9-15v. 5a, 18/9; 0- 9 -15v. 6a. 23/9:
450- O-450v 250mA, 6.3v. 4a, C.T. 5v. 3a 69/9 0- 9-15v. 8a. 28/9.
AUTO (Step up /Step down) TRANS.
FILAMENT TRANSFORMERS
200 -250v. 50 c/s primaries 6.3v. 1.5a, 5/9: 8.3v. 0-110 /120- 230/250v. 50-80 watts. 13/9; 150
2a. 7/8. 12v. la, 7/11: 6.3v. 3a. 8/11; 6.3v. 6a, watts, 27/9; 250 watts. 49/9: 500 watts, 99/9
MIKE TRANSFORMERS 120:1 8/9.
17/8; 12v. 1.5a, twice, 17/8.
TWEETERS H.A J ohm 25/9 15 ohm 25/9 SPECIAL PURCHASE OF TRUVOX D84
250-0-250v
300- 0:300v
300 -0-300v
any Pre -amp. or Radio Tuner.
ARMSTRONG,
TRUVOX,
o
Carr.
4 -TRACK TAPE DECKS
7/6
speeds 76; 31:11 i.p.s.
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.
LEAK, SCOOP PURCHASE OF HIGH QUALITY
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. Suitable for power requirements of almost
3
LIVERPOOL day)° CENtral 3573 QUAD, ROGERS, LINEAR, W.B.,
FANE, WHARFEDALE, GOODMANS
Edgware Road W2
LONDON 238
GARRARD, GOLDRI NG, GRAMPIAN,
(Half-day Thursday)
Tel: PADdingtea I631
MANCHESTER
1
60A -60B Oldham St. Tel: CENtral 2778
(No half -day) New large store.
MIDDLESBROUGH
106
Newport Road.
SHEFFIELD
Tel: 20716
R.S.C. 4/5
Tri dnesday)
Tel: 47096
Str.«.
13
RECORD CHANGERS
Brand new Garrard 3000 LM.
Very latest model. Normal
GNS.
LUSTRAPHONE, SHORE, RESLO, Retail price approx. 112.16.0
Carr. 5/8
and lightHeavy
TANDBERG, FERROGRAPH Products weight Turntable
pick-up arm. High fidelity Stereo/
stocked. Usual credit terms available. Mono cartridge. Fully guaranteed.
Geheng.
Castle
Market !lido,
(Half-day Thursday) J
11
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
dB down 15 dB of Negative Feedback la used. H.T. of
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
VACANCIES FOR STAFF
Chassis Is not alive. Kit is complete In every detail with fully punched Gold Hammer
AT VARIOUS BRANCHES
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
SHOP EXPERIENCE UNNECESSARY
and 5 monthly payments of 22/6 (Total 16.15.0) for assembled unit
71
300v. 25mA and L.T.
R. S.C. Sl/PER IS/iI/F/4+4MPUf/ER R.SC.SCIAER30STEREO44fPI/f/ER
FULLY TRANSISTORISED
-250v A.C. i
A DUAL CHANNEL VERSION OF Tilt:
Kl? PRIi -ULY INTRODUCE TWO
Operation.
SUPER 15. Employing Twin Printed Cir200
T
OUTPUT 15 WATTS R.M.S. into 14 ohms.
OUTPUT
OUTPUT 15 WATTS R.M.S. into 3-4 ohms.
Maximum Instantaneous Peak Power Out- I
yPR 28 watts.
PRINTED
CONSTRUCTION.
LATEST MOLLARD
MULLARD TRANSISTORS
ÁD349, ÁD349, 0C127Z, OC81Z, OC44,
OC44, OC81Z, OC44, AC107.
COMPLETELY NEW UNITS WITH
TEl lINIt AL
SPECIFICATIONS
COPPA RING MORE THAN FAVOURABLY WITH SIMILAR AMPLIFIERS OFFERED AT 2 -3 TIMES THE
- '
COST.
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
5 POSITION
INPUT SELECTOR
SWITCH
EQUALISATION
to
Standard R.I.A.A. and C.C.I.R. CharHead/Microphone.
acteristics for Gram and Tape Heads.
Operation of the Input Selector Switch
FULL TAPE MONITORING FAG
assures appropriate equalisation.
ILITIES SENSITIVITIES; Magnetic
Rigid 18 s.w.g. Chassis. Size approx. l2'
P.U. 4m.v. Crystal or Ceramic P.U.
Wide, 3' High, and 8' Deep.
400m.v. Microphone 4.5m.v., Tape Head
Attractive Facia Plate and Matching
2.5m.v. Radio /Aux or Ceramic Y.U.
Knobs. Neon Panel Indicator.
Above facilities, etc., except for GangFREQUENCY RESPONSE: 20-20 000
IMPORTANT NOTE. Rated output
ing and Balance Control, apply also to
c.o.s.
in
R.M.S.
and
not
are
given
speech
figures
Super 15.
TREBLE CONTROL +15d.b.to- 14.d.b.
and music or 1.H.F.M., otherwise we could
THESE UNITS ARE EMINENTLY
at 10 Kc/s.
obviously quote much higher outputs.
SUITABLE FOR USE WITH ANY
BASS CONTROL +12d b to -15d b at
MAKE OF PICK -UP OR MICRO50c/s.
PHONE (Crystal, Ceramic, Magnetic, Moving Coll. Ribbon)
HARMONIC DISTORTION at 10 Watts R.M.S.1.000 c. n.s. 0.29°ó
CURRENTLY AVAILABLE. REGARDLESS OF THE
HUM LEVEL: -75d.b.
NEGATIVE FEEDBACK 52d.b.
COST. SUPERB SOUND OUTPUT QUALITY CAN BE
Complete
OBTAINED BY USING WITH FIRST RATE ANCII.LARY
details nd point to point wiring
wiring diagrams 94 Gns . /
EQUIPMENT,
Carr. 12/6
If preferred printed circuit can be supplied with parts soldered
All required parts, point to point wiring dia-'
in and tested for 21/- extra.
gras
GNSi.
m and detailed Instructions. If required
printed circuits can be supplied with appropriate
Or
and tested, with our usuali
components
2 Gsae Ca r.
assembled, soldered and tested for 2 gas. extra.
unitffactory built.
Terms Deposit6gns,&9 monthlypayments 88/ 8.Tota1 $22.14.8.
Or Deposit 38/- and nine monthly payments 26/7 Total 113.17.3.
Or unit completely assembled ready for use Carr. 15/- 23 gus.
Send S.A.E. for leaflet.
Or Deposit 14.14.6 & 9 monthly payments 48/8 Total 828.11.0.
.
.
.
°ó
8
:
PRACTICAL
644
December, 1965
WIRELESS
R.S.C. STEREO 20 /HIGH FIDELITY AMPLIFIER
PROVIDING 10/14 WATTS ULTRA LINEAR PUSH -PULL OUTPUT ON EACH CHANNEL
" 1111: I:" GRAM., RADIO OR TAPE. INTENDED FOR THE
HOME OR STUDIO BUT SUITABLE FOR LARGE HAILS OR CIL It»
and Based on a current Mullard design and employing valves
SCI'l'ABLE w,
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
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.
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
Ih.
Complete set of parte with point-to.
point wiring diagrams and incirnctions, 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.
I
1
-FI TAPE RECORDER KIT 252
AUDIOTRINE HI
LOW COST, CAN BE ASSEMBLED IN AN HOUR
3
Gns.
171 6.
Gns:
REALISM AT INCREDIBLY
Amplifla r
The Audfotrine High Quadty Tape
Incorporating the latest Collar() Studio Tape Transcriptor.
Tape
Spool,
a
of 3 speeds. High Flux P.M. Speaker, empty
with negative feedback equalisation for each
contrasting
Carrying Cabinet tastefully covered in twoIndiv
Roelof Best Quality Tape and a Handsome Portable high
dually
it
purchased
cost
Total
and
circuit.
x
15
x
Ellin.
148
shades of Rexine and Vynair. Size
the 460 -480 class. S.A.E. for leaflets. 'PERMS. Deposit
approximately 240. Performance equal to units in
ONLY 3
4 glee. and 12 monthly payments of 42/- ('l'otaI 28 (100.)
üi é
R.S.C. A10 30 WATT ULTRA LINEAR HIGH FIDELITY AMPLIFIER
JoINTs
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
Alt components are chosen for
Is used with 807 output valves.
A
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
two separate Inputs
RADIO FEEDER UNIT. An extra Input with associated vol. control is provided so thatand
15 ohm speakers
50 cis. A.C. Maine output for 3
200
-250v.
mixed,
and
"Mike"
can
be
each as Gram
Carr. IO)Complete kit of parts with fully punched chassis and point -to -point wiring diagrams and
guarantee,
Watructioa Supplied factory built with EL34 output valves and 12 mouths'
for 14 One. If required perforated cover with carrying handles can be supplied for 19/9.
16 gns.)
Bend 0.A.11. for leaflet, also speaker. Terms: DEPOSIT and 45/- 9 monthly payments of 32/4 ,Total
11
INTEREST CHARGES REFUNDED
Gns.
AccountsaetLedlno months
Positions
LINEAR 'TAPE PILE -AMPLIFIER. 'l'ype LP/I. Switched Equalisation.
sec.. and Playback. F)2184 Recording Level
for Recording at liln 311n., 7á1n, perlink
between a Collar() ('ape Deck 91 Gns.
Indicator. Designed primarily as the
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
o ö
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 Payments 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 required we highly recommend this unit ith at
amazing performance. Please state
whether 3 or 16 ohm required.
R.B.C. JUNIOR BASS REFLEX CABINET. Designed 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.
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 finish. Reconnnetelet for
£4.19.6
£4.7.6
sockets with associated controls allow
mixing of "mike" and gram., as in A10. High
sensitivity. Includes 5 valves. ECC83, ECC83,
xd
Aud,nerme
u.se
EL84, EL84, EZ81. High Quality sectionally wound
9Peaket
output transformer specially designed for Ultra .?.
£5.19.6
öy isms
Linear operation and reliable small condensers of
AUDIOTRINE CORNER
current manufacture. INDIVIDUAL CONTROLS
CABINETS
CONSOLE
FOR BASS AND TREBLE Lift" and "Cut ".
Strongly made. Beautiful
Frequency response ±3 dB 30-20,000 Os. Six negapolished walnut veneered
tive feedback Loops. Hum level 60 dB down. ONLY
design.
finish.
Pleasing
23 m1111volts input required for FULL OUTPUT.
For
and microphones. Comparable with JUNIOR MODEL.
Suitable for use with all makes and types of pick -ups
Hin. speaker.
up
to
MUSICAL
For
RECORDS.
PLAYING
or
LONG
STANDARD
the very best designs for
Approx. 20 s 11
etc.
INSTRUMENTS such as STRING BASS, LEAD or RHYTHM GUITARS,
49/9
öln.
1.5a, for supply of a RADIO
OUTPUT SOCKET with plug provides 300v. 30rnA, and 9.3v.200
-250v. 50 c.p.s. Output for 3 STANDARD MODEL. To
FEEDER ('NIT. Size approx. 12 x 9 x lin. Fol A.C. mains is fully
punched. Full instruc- take up to loin. speaker.
and 15 ohms speaker. Kit is complete to last nut. Chassis
size 27 x 18 a 18in.
r.
Only
supplied.
8 Gns. Car
tions and point -to -point wiring diagrams
l0l(Or factory built 51/6 extra,.
5 Gns. Carr. 761
If required louvred metal covers With 2 carrying handles can be supplied for 18/9. TERNS SENIOR MODEL. To take up to 12in. speaker and
ON ASSEMBLED UNITS. DEPOSIT 33/3 and 9 monthly payments of 24/1 (Total with Tweeter cut-out. Size approx. SO x 30 x 16in.
etc.
Mikes,
Speakers,
Cabinets,
detailing
leaflet
for
Illustrated
Send
S.A.E.
£12.10.0).
speaker
TWo input
R.S.C. STEREO /TEN HIGH
(Reoommended for use wits Audiotrine
system.) Carr. 8/0.
QUALITY AMPLIFIER
stereoA complete set of parts for the construction
on
phonic amplifier giving 5 watts high quality output
each channel (total 10 watts). Sensitivity is 50 millivolts. Suitable for all cristal stereo heads. Ganged
"lift"
for
variation
equal
Bass and Treble Control give
and "cut". Provision is made for use as straight
ECC83,
(monaural) 10 watt amplifier. Valve line -upspeakers.
ECC83, EL84, EL84, EZ81. Outputs for 2-3 ohm
inPoint -to-Point wiring diagrams and
leaflet.
for
8 Gns.
structions supplied. Send S.A.E.
Full constructional details and price list 216.
Carr. 10/
Or supplied factory assembled with 12 months' guarantee for E11.7.6.
Terms: Deposit 2 gus. and 9 monthly payments of 24/2 (Total £12.19.6).
Always in Stock at keen prices SINGLE
GL3A MINIATURE 2-3 WATT GRAM and AUTO
RECORD PLAYING
AMPLIFIER. For use with any sin;le UNITS, PICK -UPS,
CARTRIDGES,
ohm
2/3
or auto-change unit. Output for
MICROPHONES, CABINETS
speaker. For 200 -250v. A.C. mains. Glee
Only
COMPONENTS
111 x 24 x 211n, Volume and
and
VALVES
59/6
ToneControlawith Switch,
TOO NUMEROUS TO LIST
of a
,
Terms available.
8 Gns.
SPEAKER
H1 -FI
AUDIOTRINE
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 extended frequency range
ensure surprisingly realistic
reproduction.
10
Standard
rating.
watt
C5rr
£4.19.9
Or Senior 20 watt. 26.19.6. Carr. 7/6.
December, 1955
PRACTICAL
WIRELESS
645
R.S.C. BASS -REGENT 50 WATT AMPLIFIER
EXCEPTIONALLY POWERFUL HIGH QUALITY ALL -PURPOSE
For lead, rhythm, bass guitar and all other musical instruments
AN
UNIT
For vocalists, gram, radio, tape and general public address
*
t&1gtit
"
Full Range of FANE and GOO UMANS 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 controlled. Cabinet is of substantial construction and attractively finished in
two contrasting tones of Resine and
Vynair. Size approx. 24 x 21 a 13 ins.
Send S.A.E.
Carr.
for leaflet.
17/4
Or deposit 24.14.8 and 12 monthly
payments of 49/- (Total 321 gas.).
GI5 15 WATT AMPLIFIER for Lead
or Rhythm Guitar, 'Mike', Gram or Radio
R.S.C.
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.
watt
quality
high
output.
Incorporating high flux 12ín. 10 watt.
R.S.C. G5 AMPLIFIER
loudspeaker. Sensitivity 40 mv. High impedance
input.
Handsome cabinet (size 14 x 14 x71n. approx.) finished in Rexine /Tygan, 200 -250v. lack
A.C. mains.
Suitable for Lead or Rhythm
Or Deposit 30/9 and 9 monthly payments
19
Guitar in home or small club etc.
of 22/3 (Total 11 Gus.) Carr. 7/6
R.S.C. BATTERY CHARGING EQUIPMENT Guaranteed 12 months
4
..6
All for A.C. Mains 200-250 v
SOcs
Assembled A 9sEMBLED
amps 6 /12v. 6/12 v. S amps.
Fitted, Am- Fitted Ammeter
4
meter and and selector
plug for 6 v.
or 12v. charging. Louvred steel case
with stoved grey hammer finish. Fused
and ready for use with mains
and output leads and clips. 59 9
Or Deposit 12/- and 5 monthly Carr. 4/6
payments 12 /- Total 23.12.0
plug for 6 v. or
12 v.
Louvred
metal case finished attractive
hammer
blue.
Fused. ready for
use with mains
and output leads
39/9 Carr.
59 9
R CTIFOIERS
(BRIDGE)
2vL SNAMP
F.W.
ONLY
9/9
6v. or12y.
22/9
28/9
25/9
35/9
£19.13).
RE- ENTRANT
SPEAKERS. For outdoor or
Factory use, 8 ohms. 8 watts.
Pius 4/6 carriage
TANNOY
6/12v. 15a. 35/9
COMPLETE POWER PACK KIT
Consisting of Mains Trans.. Metal Rectifier Double electrolytic smoothinc choke,
chassis
200 /250
>
HI -FI
GROUPS.
A Four input,
two volume control HI-Ft unit
with
separate
Bass and Treble
'Cut' and 'Boost'
Decontrols.
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.
or Deposit 5s and 9. monthly
payments of 37/ -. (Total
17
HEAVY DUTY CHARGER KIT
hilt v. 6 amps., variable output
Consisting of Main Transformer 0-200KITS
230 -250 v.; F.W. (Bridge) Selenium RectiBATTERY CHARGER
Ammeter Variable Charge Rate
Consisting of Mains Trans- fier:
Panels, Plugs, Fuses.
59/9
former, F.W. Bridge. Metal Selector
Rectifier, well ventilatedsteel Fuseholder and circuit. Carr. 5/6
case. Fuses. Fuse -holders SELENIUM RECTIFIERS F.W. (BRIDGED)
Grommets, panels, Heavy
la. 3/11 6/12v. 3a. 9/9 8/12V. 6a. 15/3
Duty Clips, circuit. Carr. 3/6 6/12v.
6/12v. 2a. 6/11 6/12v. 4a. 12/3 6/12v. Ma. 26/9
1 amp
As above with ammeter
6v. or12v.2 amps
6v, or 12v. 2 amps, inclusive of ammeter
3/9.
It v. or 12 v. 4 amps with
6/12v. amo 27/9 Ammeter and variable
Less meter.
charge rate selector
CHARGER AMMETERS
0-1.5a., 0 -4a., 0-7a., 8/9 each.
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
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 sensitivity. 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
CONVERSION
BMI. An all -dry
battery eliminator. Size 51 x
41x2In. approx.
Completely replaces batteries
supply 1.4v and
90v where A.C.
mains 200-250v.
50 c/s Is available. Suitable for all battery portable
receivers requiring 1.4 v. and 90v. Complete
kit with diagram 39/9 or ready for use 48/9
MIS
Page 643
TRANSISTORISED SOUND MIXER
Enables mixing of up to 4 standard lack inputs,
i.e. min., tape, gram, tuner, etc., into single
30 WATT HI -FI AMPLIFIER
output. Compact and completely self- 49/9 FOR LEAD, RHYTHM BASS GUITAR
contained, uses standard 9 volt battery
and for VOCAL or INSTRUMENTAL
separately controlled inputs so that
two instruments or "mike" and pickups can be used at the same time. Loudspeaker is a heavy duty flux 12ín 20
watt model with cast chassis. Cabinet
is covered in contrasting shades of
selector.
Also selector
Aodresses
Covered in two -tone Rexine/
Vynair. Ideal for vocalists and
Public Address. Normally supplied 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).
_
High -fidelity push-pull output. Separate bass
and treble "Cut" and "Boost" controls. Twin
variable
charge rate
IN
COLUMN SPEAKERS
R.S.C.
UNUSUALLY
POWERFUL
LOUDSPEAKER
COMBINATION consisting of a FANE HIGH
FLUX 15ín. 30 watt unit PLUS a FANE 12ín. 20
29
EX
ACCOUNTS SETTLED
6 MONTHS
watt unit with extended frequency response.
4 Jack Socket Inputs and two independent Volume Controls for simultaneous use of up to 4
pick -ups or 'mikes'.
* Separate
cabinets fully covered in contrasting tones of Rexine /Vynalr with gold trimming for speakers and amplifiers.
Bass and Treble Controls giving
* Separate
'Boost' and 'Cut'.
Send S.A.E. for leaflet. Or call at one of our
many branches and compare the Bass- Regent
units at more than three times the cost.
dOwith
Gns. Or deposit £7.16.0 and 12 monthly payCa r. 25/- meats of 81/6 Total of 54 Gns.
_
R. S. C.
INTEREST CHARGES
REFUNDED ON H.P.
52/9
LOUD-
27!6
WATT AMPLIFIERS
12
BRAND NEW
arr
EX- GUITAR AMPLIFIERS 8 Gns. 6/b
Model
Manufacturers' discontinued
Push -pull output. Latest high efficiency
valves Dual separately controlled Inputs
for 'Mike' and gram. Separate Bass and
Treble Controls. High Sensitivity. Output for 3 or 15 ohms speaker. Guaranteed
tested and in perfect working order.
V.H.F. /F.M.Radlo Tuner
JASON FMTI
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 alignment 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.
www.americanradiohistory.com
and
circuit.
COMMUNICATION
RX
4
60
For
A.C. mains. Output
mA, 6.3 v., 2a.
V.
250 v., 60
DE LUXE
I9
, l'
RECEIVERS
BAN D
220/240v 50/66 g
mains opera
Lion.
Frequencies covered 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. Headphones. external speaker socket. Other features 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
make. N',rmal price approx. 212. £6.19.9
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
Gf15.
heavy or light effect). Volume
and Swf!ch.
;
4
CONE
SPEAKERS U8watt
each
39/9
PRACTICAL.
646
December,
WIRELESS
1965
WEYRAD
TRANSISTOR
COILS
The P50 series remain the most popular and widely used components for Medium and Long -wave
Transistors Superhets:514 ea.
P50 IAC Oscillator Coil for 176 pF tuning ...
517 ea.
P50 1CC Ist & 2nd I.F. Transformers
61- ea.
P50 3CC 3rd I.F. Transformers
All mounted in individual cans ;;sin. diam. x ;in. high.
1216 ea.
...
...
RA2W Ferrite Rod Aerial 208 pF Tuning ...
916 ea.
...
...
...
...
LFDT4 Driver Transformers ...
1016 ea.
...
OPTIA Output Transformers
916 ea.
...
...
PCAI Printed Circuit Panel ...
21- ea.
...
..,
...
Constructor's Booklet
Van
COILS
RECEIVER
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
ßU
()CATHODE RAY OSCILLOSCOPE
BASIC RECTIFIER
PHOTO ELECTRIC CIRCUIT
TIME DELAY CIRCUIT
:QUART WAVE GEI.. iATJ.T
SIMPLE TRA. SMITTS I
TRANSI.iTO.t EXPERIMENTS
OSCILLATOR
CH
BASBASIC
ELECTRONIC
SIGIAL TRACER
W BASIC COMPUTER CIRCUIT
BASIC RADIO RECEIVER
I.I4.1R3E CODE OSCILLATOR
¿T:. ETC.
This complete practical course will teach you all rite basic facts
of electronics by malting eenerlments and buildin apparatus
You learn how to recognise and h and le ,.li types of components
a circuit diagram. You see how
-their symbols and how to read
circuits are built and how they work HI' USING THE OSCILLOSCOPE PROVIDED Applications of all the main
electronic circuits are demonstrated -radio reception and
transmission; photo- erectrics; computer basics; timers; con-
1
trol circuits, etc; including servicing techniques. NO MATHS
USED OR NEEDED. NO rrtEORt' NEEDED. NO PRE %IOUS KNOWLEDGE OR EXPERIENCE NEEDED. Tutor
Send now for FILLE
.service available. No extras needed.
DETAILS without obligation to ad Irece below
TO: LERN " %KIT, RADIO HOUSE,
40
RUSSELL STREET, READING
Please send free Brochure without obligation --
POST
S1G -GEN. A versatile Sigual lujerso. some'
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
' Complete sei of part.
measures 41 x 3}
with to n.tracrinns. 19/6. P. a P. I/h
fUNINd tONDeNSERS. Au -paged hoe onaun
THE
.
lip;_LUOI J-à;
BASIC AMPLIFIER
RADIO EXCHANGE
Thing no constructor
and learn Electronics
the LERNAKIT way
VALLi EXPERUIEYf,
SPECIAL 'BARGAINS FROM
40
D
OVER
i L
CIRCUITS /EXPERIMENTS
m+nufactsvr ,nth
ur,ly 6/6.
a P 1di.
AUDIO AMPLIFIER.
1200mW TRANSISTOR
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
P.
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. Cheeku of RF and And.o Transistor -. Aso checks ire
level and dads. All parts ready to be assemb.noise
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.
N AME
RADIO
ADDRFISS
61, HIGH
NOW
tNa rpreaestarleea rmployedl
P.W. 12165
,lox 'melon dry
BRAND NEW'
oiu6l5. With n.chlator seetmn
See
EXCHANGE
STREET,
CO.
BEDFORD
facing page for other items
www.americanradiohistory.com
December, 1965
PRACTICAL
WIRELESS
647
NOT BUILD ONE OF OUR
PORTABLE TRANSISTOR
RADIOS...
All components used in our
receivers may be purchased
separately if desired. Parts price
lists and easy build plans available separately at prices stated.
Overseas post 101 -.
BACKED BY OUR SUPER AFTER SALES SERVICE
FIRST FOR QUALITY, PERFORMANCE & PRICE!
NEW ROAMER SEVEN Mk IV
WAVEBAND PORTABLE OR CAR RADIO
* Now with
PHILCO MICRO -ALLOY
TRANSISTORS
FULLY TUNABLE ON ALL WAVEBANDS
stages-7 transistors and
diodes
7
Amazing performance and specification
R.F.
9
2
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
P. & P.
OF PI RATE STATIONS etc Parts Price List and easy build plans 3l -(FREE with kit)
5,'6
*
.I9.6
TRANSONA
Light,
".
Luz. all at
FIVE "Home.
G.P. Durham.
amazed at volume and
performance ... has really come
up to my expectations."
S. G. Stockton -on -Tees.
.
stages-6 transistors
and 2 diodes
Our latest completely portable transistor radio covering
medium and long waves.
Incorporates pre- tagged circuit board, 31n. heavy duty
speaker, top grade transistors, 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.
New
A.F.N.
good volume
8
Parts
Price
build plans
(Free with kit)
easy
L3.9 6
Total cost of all
parts now only
List and
21-
P.
&
P.
POCKET FIVE
parts now only
42/6
116. (FREE
P. & P
NOW
WAVEBAND
-6 transistors and 2
!
8 stages
2
-6 transistors
diodes
Listen to stations half a
world away with this 6
waveband portable. Tuneable on Medium and Long
waves. Trawler band and
two Short Waves. Sensitive ferrite rod aerial and
telescopic aerial for short
waves. Top grade transistors. 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.
P. & P.
Total cost of all
Ip
parts now onlyy
9.6
3t6
p
(FREE with kit)
Parts Price List and
easy build plans 21-
t`3.
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 evening 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
P.
parts now only
3/6.
Parts Price List and easy build plans
59/6
P-
116
(FREE with
kit)
SUPER SEVEN
9
TRANsSTOHS
-ALLOY
!
and
*
8 stages
with kit)
31 -.
NEW
ROAMER
SIX
WIT,: PHILC.t h Gill
n.r.
6
TRANSONA SIX
battery available anywhere).
Parts Price List and easy build plans
Total cost of all
stages -S transistors and 2
diodes
3i6
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 supersensitive 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
7
Fully tunable over Medium and Long
Waves and Trawler Band. Incorporates Ferrite' rod aerial, tuning condenser, volume control. new type fine
tone super dynamic 22 In. speaker etc.
Attractive case. Size 6k x 44 x l.t1awith red speaker grille. (Uses 1289 battery available anywhere.)
Total cost of all
Parts Price List and easy build
P. & P.
parts now only 42/6 3f6.
plans 21 -. (FREE with kit)
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 incorporating2 R.F. Stages, push -pull output.
3in. speaker (will drive large speaker). Size 7* x 51 x 1í1a. (Uses 9v
battery, available anywhere.)
Parts Price List and easy
Total cost of all
19.6 P. & P.
parts now only
E3.
316
build plans
with kit)
21-.
(FREE
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
PRACTICAL
648
December, 1965
WIRELESS
STERN-ELYNE
H
I
H
G
F
IO"
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 Amplifier 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).
D
E
L
I
T Y
E
Q U
I
VHF /FM long and
Self-powered
medium waves. FM 87.5.108.6 Mc s
AM.MW 522 -1,830 Kc)e. LW 142270 Kets. Multiples output.
Built and tested 24 fins. (P. d P. 7)0).
(9)
Mullard "5 -IORC"
Amplifier
"5 -10" complete m
Passive Control Unit
providing up to 10 watts high quality
reproduction with an input of 600mV.
popular
The
,orpvrating
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.
(6)
P M
E
T
N
Tuner
Tudor AM /FM
(5)
(f) Mullard "IO Plus
Stereo Amplifier
I
Amplifier
(16) )LIO Power
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).
Mullard 3 -Valve Pre Amplifier Tone Control
Designed
mohair
for
the
Stern
Milliard range of Monophonic Power
Amplifiers.
OF PARTS 210.0.0.
Mullard Dual Channel KIT
Bailt and tested £18.18.0 (0.
Pre -Amplifier
(2)
L 6f-).
A four -valve design for both steneand Monophonie operation.
c11810.0.
te
pho
KIT
Built and !taled 215.0.0 (0. L 6 /-).
(17)
Mullard "3-3RC"
(10)
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).
A high quality
ic
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
N -1 system at a later date all
that is requiredls a suitable tape deck.
yon
(8)
(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
Built and rested 818.18.0
Mollard "5 -10" Main
Penes fr both
Amplifier
Bailt
une with Mallard '2- or 3 -valve
pre-ampliftere with which an undistorted power output of up to 10
For
(I
watts is obtained.
KIT OF PARTS 210.0.0.
Built and tested 218.10.0 (C.
for 216.10.0 (C.
A
1.
1)
The "Mono -Gram"
& 1. 6 /0).
3
A
1, 2
and 14, 3/- each;
and 19, 3/6 each; 7. 8. 9,
10, 21- each; 11, 2/8 each;
13, 6/-. All Post Free.
6
lis
(7)
.i
MULLARD
0).
general
purpose amplifier
quality
of
ideally suit-
.
Kits of Parts but may be
purchased separately if
required.
Items
3
able
for Dance Band,,
Clubs.
Indoor and
Hotels,
Factories.
outdoor Public Address requiring
a powerful robust portable Amplifier 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 Lists
are supplied Free with
30
VERITONE 30
AMPLIFIER
outstaadmc
Detailed
I L 10/ -l.
watts undistorted output.
KIT OF PARTS 24.10.0.
Built and tested 68.0.0 (C. d I.
Above inoorporating Partridge Oat nt Transformer 21.6.0. extra.
10) -).
Instruction Books and
VERITONE
quality performance producing up to
two
Fully descriptive leaflets
available on any of the
above items.
and tasted 830.8.0 (C.
A small Amplifier of genuine high
r x am. Londepeakers and Portable
Case
(C. & 1. 514.
units purchaasd to-
otthee:
Price 18 Gns.
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 control. Valve line-up: 01.84. 01e86,
07.80.
lf
ln. Silver
8} x 4 r
anodised finish. Attractive iront panel
silver grey finish with contrasting
lettering and knobs. Sise 81. x 21.in.
Chassie else
Fully assembled and tested
Gus.
6
(C. &
t gIt 0:
2:6
'..;
2 -VALVE
PRE -AMPLIFIER
Employing two EF80 valves and
designed to operate with the Mulard
MAIN AMPLIFIERS but also perfectly suitable for other make,. Nnw
with new design front panel.
KIT OF PARTS 20.0.0.
Built and tested 20.10.0 (0.d
$
*el
010 th
1.
6(-).
(12)
Stereo Tape Pre-
Amplifier Model STP-I
For use with current Travoz, Brenell 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).
a..
.
O
(13)
Mullard Type "C" Tape
Pre-Amplifier
for moot, f -track
Mono
Tape Decks. Now with new design
Buitable
front panel.'
KIT OF PARTS 214.0.0.
Built and tested 219.10.0 (0. &
1. 716.
(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).
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:
x AF125,
x AFI21, 4 x AFI 16.
Diodes: 4 x 0A79, Variable Capacity Diode, Solid State Full Wave
Bridge Rectifier, 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: 87.5108.5 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.
I
1
1
I
PRICE 25 G NS. Carriage & Insurance
716
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,
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.
I
PRICE 39 GNS. Carriage & Insurance
Teak case optional extra.
101 -
Teak case optional extra.
NOW ON DEMONSTRATION AT ALL BRANCHES
ETERN-ELYNE
SEE
FOLLOWING PAGE FOR ADDRESSES'
www.americanradiohistory.com
PRACTICAL
650
December, 1965
WIRELESS
5TERN-ELYNE
ELECTRONIC CENTRES THROUGHOUT GREAT BRITAIN
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.
Originally 23 Gus.
Carriage and Insurance 15 /- extra. Credit
Terms 22.18.0 deposit and 12 monthly payOUR
PRICE.
credit
price
220.10.0.
total
of
mente 21,9.4,
1$
TR2 PORTABLE TAPE REOORDER.
Gns.
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 Accessories at all Branchu or order with
confidence by mail.
Tape RecTRI PORTABLE TAPE RECORDER, A high quality Portable
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
Indicator.
Level
Record
Tape
Counter.
erasure.
accidental
prevent
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
Originally 28 Gus.
and Insurance 16 /- extra. Credit Terms:
23.8.0, depost and 12 monthly paymtente
of 21.12.3. Total credit price 222.10.0 OUR PRICE
20 Gns.
AMERICAN
RECORDING TAPE
600ft. Std. Acetate
900ío. LP Acetate
52ìn. 1.200ít. LP Acetate
..
..
,
.
7Ì0n 1,200ft. Std. Polyester..
5in. 1,200ft. DP Polyester ..
710. 1,800ft. LP Pulyestet ..
5'In.
710.
8/8
10
/-
12/8
12 /8
15/-
1..001t. DP Polyester .. 22 /6
2,460fí. UP Polyester .. 25 /P. 1/- per reel. 4 or more reels
P. &
POST FREE.
ETCH YOUR OWN
PRINTED CIRCUITS
complete kit of parts to
make your own printed circuit
board to your own specification, 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.
A
*POSITIVE
MEDIUM AND
EARTH.
*SIZE
7 x 2
x 7in.
LONG WAVES. *12 VOLT
*Push Button Wave Change.
Ready ballt complete with 7 z 41n.
speaker fitted to baffle fixing brackets,
all nuts and bolts and fitting instructions.
Optional Extras: Chromium plated weatherproof telescopic aerials. Type
1, 22In50nL, 19/8. Type 2, 1210.%4310, E9 /6. Type 3, fully retractable
Depth
wing.
14in.. 39/6. AU plus P & P. 2/6
and locking lm.150in.
below
if purchased .separately.
9 2 Gns
P.
&
P. 5/-
LIVERPOOL
Tottenham Court Road, W.1 MUSeum 5929/0095. Halt Day Saturday.
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.
19
23
NOW ALSO OPEN AT:
220 Edgware Road, W.E. PADdington 2607 (New-Max).
CROYDON
12 Suffolk House, George
Street, MUNIcipal 3260, Halt Day Wednesday.
Street, Brletot
NEW CENTRE
Opening
Shortly at
EASTOWN
HOUSE
LINCOLN ST.
NOTTINGHAM
BRISTOL
26 Merchant
ANOTHER
1.
Bristol 20281. Open
6
days a week.
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.
December, 1965
PRACTICAL
SURBITON PARK RADIO
MARTIN
AUDIOKITS & RECORDAKITS
Cash 212.17.8
F.M. TUNER i. N11 S Nos. 15. 16 and 17
(H.P. Price £13.17.6)
Or Dep. 51/6 and 12m. pyrnts. of 18/10
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
(H.P. Price £15/7/0)
Or Dep. 57/- and 12 m. Dimas. 20/10
For 15 Ohm Speaker, Cash 215.0.0
(H.P. Price £16.12.0)
Or Dep. 62/- and 12 m. pymts. 22/6
All above Include Front Panels, Knobs and Instructions.
TWO TRACK RECORDAKIT AMP. (Valve) FOR STUDIO
Cash 211.11.0
DECK, 6 valves, controls, self powered
(H.P. Price £12.11.0)
Or Dep. 47/- and 8 m. pymts. 25/6
COLLARD STUDIO DECK 3 speed latest Two Track Cash 210.19.8
(H.P. Price £12.0.0)
441- and 8 m. pymts. 24/6
Or D
Cash 229.19.8
COMPLETE KIT with case, saki... tape and mIo
(H.P. Price £32 8.0)
Or Dep. 1201 - and 12 m. pymts. 44/Cash 212.12.0
FOUR TRACK AMP. as above
(H.P.Price £13.12.0)
Or Dep. 52/- and 8 m. pymts. 27/6
FOUR TRACK COLLABO DECK Marriott "X" Series heads
Cash 213.19.8
(H.P. Price £15.2.0)
Or Dep. 56/- and 12 m. pyrnts. 2016
COMPLETE KIT with case, spkr., tape and mie.
Four Track Cash 233.19.8
(H.P. Price 136.14.0)
Or Dep. 136 /- and 12 m. pymts. 49/10
TAPE PRE-AMP for Studio Deck, self powered
Two Track Cash $8/8/0
(H.P. Price 19/9/0)
Or Dep. 34/- and 6 m. pymts. 25/8
Four Track Cash £9.9.0
TAPE PRE -AMP as above
(H.P. Price £10.9.0)
Or Dep. 39/- and 6 m. pyrnts. of 28/4
.
We are leading stockists for all Martin Constructional Kits
AMPLIFIERS TUNERS
Selection
WIRELESS
651
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
watt
WHARFEDALE SUPER 8 /RS /DD
WHARFEDALE SUPER 10/RS /DD
FANE
012 /10
heavy Duty
Cash £5.5.0
Cash £8.14.3
Cash £10.18.0
(H.P. Price 111.18.0)
Cash £17.10.8
H.P. Price 118.1.8.6)
121n. 20
Or Dep. 44/- and 8 m. pyrnts. of 24/3
GOODMANS MAXIM
Or Dep. 70/6 and 12 m. pyrnts. 25/8
MOTORS PICK- UPS Selection
Cash £5.10.0
GARRARD SRP10 Mono
Cash £7.10.0
GARRARD Model 1000 Mono
Cash £8.10.0
GARRARD Model 2000 Mono Large Table
(H.P. Price 15.10.0)
Or Dep. 34/- and 6 m. pyrnts. 26/GARRARD Model 3000 Stereo Lightweight arm.... Cash £11.11.0
(H.P. Price £12.11.0)
Or Dep. 47/- and 8 m. pymts. 25/6
Cash 212.10.0
GARRARD S.P,25 Less cart.: Single player
(H.P. Price 213.10.0)
Or Dep. 50/- and 8 m. pymts. of 27/6
Cash 213.0.0
GARRARD at 60 Less cart.: Heavy table
(H.P.
Price £14.0.0)
Dep.
Or
52/- and 12 m. pymts. 19/Cash 222.10.0
GARRARD A 70 De Luxe changer, Less cart
(H.P. Price £24.6.0)
Or Dep. 90/- and 12 m. pymts. 33/Cash 227.10.0
GARRARD LAB 80 Push button Oper., less cart
(H.P. Price £29.14.0)
Or Dep 110 /- and 12 m. pymts. of 40/4
GARRARD 401 Transcription Table. No arm
(H.P. Price 135.2.0)
Or Dep. 130/- and 12 m. pymts. 47/8
Cash 211.11.0
GOLDRING G66 Mono Single Player
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.)
-
Cash 227.10.0
ARMSTRONG 22210-10 watts Stereo. Amplifier
(H.P. Price £29.14.0)
Or Dep. 110 /- and 12 m. pymts. 40/4
ARMSTRONG 224 F.N. TUNER Powered
as 222.10.0
(H.P. Price £24.6.0)
Or Dep. 90/- and 12 m. pymts. 33/Cash £28.15.0
ARMSTRONG 223 AM/FM TUNER Powered
(H.P. Price £31.1.0
Or Dep. 115/- and 12 m. pymts. 42/2
Cash 228.10.0
ARMSTRONG 127 MONO 5W with AM /FM
(H.P. Price 128.12.0)
Or Dep. 106/- and 12 m. pymts. 38/10
SURBITON PARK RADIO LTD.
.
The New Picture- Book'wayof learning
ELECTRICITY(5voL.$)
IC
S ELECTRONICS (6voLs)
-
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.
You'll find it easy to learn with this outstandingly 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.
f'fff
I1111 MIN M1111.1111111MNI1.1MN
To Selray Book Co.
The series will be
of exceptional
value in training
mechanics and
technicians in electrici y, Radio and Electronics.
WHAT THIS MONTH'S
ENTHUSIASTIC READERS SAT
EVERY DAY WE RECEIVE LETTERS PRAISING THESE
BOOKS, HERE ARE A FEW FROM THIS MONTH'S POSTBAG.
-a
"Thank you
casual glance through the books was enough/
A truly excellent publication, not in the least complicated
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
it." K.L., Oxford.
in
IN
.
1111
in
wills III
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
parts), 81/- (Basic Electronics
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
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Signature
NAME............«..«..
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www.americanradiohistory.com
21, signature of
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4
.
December, 1965
WIRELESS
PRACTICAL
652
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII! IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIf! IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII11111111111111111
Heathkit models offer
outstanding performance plus
highest quality - at lowest cost
O.ST.OM
The easy -to- follow instruction manuals issued with
a Heathkit model.
kit -set show you how. You will be proud of the professional appearance and performance
Anyone can build
each
of your finished model.
A KIT FOR EVERY INTEREST
FOR HOME, WORKSHOP, SERVICE & TEST DEPTS.
.
"AMATEUR" EQUIPMENT
TEST INSTRUMENTS
AMATEUR BANDS RECEIVER
OSCILLOSCOPE Model 10.12U.
Laboratory quality at utility oscilloscope
Sin.
Model RA -I.
tuned R.F. amplifier :tage.
£39.6.6
£35.17.6
PORTABLE 'SCOPE Model 05 -1.
Covers all amateur
bands Irons 160-10 re. Half lattice
8 valve. "S" meter.
crystal filter.
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
Kit
A
compact portable oscilloscope, ideal for
Printed
servicing and general work.
circuit board. Case P. e 4, x 12 in. long.
L30.8.0 Assembled
Kit
150 w. d.c.
all amateur bands 160 -10M.
with power supply. Modulator. VFO
£22.18.0
VALVE VOLTMETER, Model V -7A.
I
in.
£35.8.0
Kit
Model DX -40U. Covers
£
419.18.6 Assembled
DX-40U
RECEIVER RG -I.
A high performance low cost receiver for the discriminating listener. Freq. coy. 600
kc;s -1.5 Mc/s and I.7 Mcis to 32 Mc /s.
Send for details.
Kit
V -7A
453.0.0 Assembled
Other kits
E39.5.0.
TRANSISTOR
DE
TESTER. Model IM -30U. Many
special features. Provides complete
d.c. analysis of PNP, NPN transistors and diodes.
435.10.0 Assd.
HARMONIC DISTORTION METER.
Freq. coy.: 20- 20,000
£24.15.0
Model HEW -I.
TV ALIGNMENT GENERATOR.
3.6 to 220 Mc,ls fundamentals.
447.10.0 Assembled
SIGNAL GENERATOR. Model
fundamental, 200 Mc /s harmonics.
RE -IU.
Up to
bands.
MULTIMETER. Model MM-1U.
Ranges: 0.1
a.c. and d.c.; 150µA to 15A d.c.; 0.212 to 20010.
418.11.6 Assembled
41
HI -FI SPEAKER SYSTEMS
Kit
COTSWOLD STANDARD MODEL
£
output on all
13.8.0 Kit
-5
v.
Acoustically designed enclosure "in the white"
26 x 23 x 155in., 12ín. bass speaker, elliptical
middle speaker, tin. pressure unit. Covers
30-20,000
I
£ 1 2. 18.0 Kit
111111111111111111111111111111111111111111111111111111111111111
DAYSTROM LTD
Dept. PWI2 GLOUCESTER, ENGLAND
c /s.
Complete kit with all controls.
to 1,500 v.
in. 50µA meter.
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
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
1.+.1-..-.14
Kit
Up to 100 Mcls
100 enV
¿19.18,0 Assembled
Wide range of models under American Mail Order
.-11-
Covers
£37.18.0
SB -IOU
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.
Kit
IM -12U.
Model
Adaptor
Variable freq.
I 1U
L8.5.0,
Scheme.
c s.
L34.0.0 Assembled
RF
£24.18.0
£39.1 6.0
in the amateur range include: SSS
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-
R.F. and H.V. probes available as extras.
LUXE
TYPE
COMMUNICATIONS
Model
DE -LUXE 6in. VALVE VOLTMETER.
1M -130. Similar spec. to model V -7A but with improved accuracy. Larger meter. Unique gimbol mount.
426.18.0 Assembled £18 . 1 8.0 Kit
-
Kit
Assembled 445.8.0
Kit
18.6
80 -10 m.
£33.19.0
The world's
13.
it
Power inputs 75 w. C.W.. 60 w.
peak C.C. phone. Output 40 w. to
aerial. Prov. for VFO.
Measures up to 1,500 volts
best selling VTVM.
(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.
£79.10.0
AMATEUR TRANSMITTER
10 -12U
I
Covers
input, self contained
Assembled L104.15.0
REGULATED POWER SUPPLY Model IP -20U. Transistorx 6_ x
RA -I
Model DX -1000.
AMATEUR TRANSMITTER.
?.
ised, 0-5-50 v. D.C. Up to 1.5 amps. Compact: 9!
447.8.0 Assembled
Kit
Assembled L52.10.0
P
SSU -I SYSTEM
practical solution to the problem of a
moderately priced speaker suitable for Stereo
Mono amplifiers where the equipment has to
Two speakers, balance control,
be compact.
ducted port reflex cabinet.
Horizontal or vertical (with matching legs).
Incl. P.T.
£ 12.1 2.0 Kit
A
December, 1965
PRACTICAL
IIIIIIIIIII! III111111111 (1(IIIIIIII1111111!IIIII(ill
IllIII111
WIRELESS
(111111111(11111111111! 111111111111111 '111111111I(!'1(IIlI(
653
IIII IIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII III1111!IInI
MODELS FOR HOME, TEST AND WORKSHOP.
BRITISH HEATHKIT MODELS USE BRITISH COMPONENTS
il'nllllll
.,..u.I .i
DAYSINOM
HI -FI AMPLIFIERS
.1111.
DE -LUXE
ALL TRANSISTOR STEREO AMPLIFIER, AA -22U.
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.
At last,
Kit
(less cabinet) 439.10.0.
Cabinet £2.5.0.
Brackets and trim for panel mounting 41.18.0.
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
TRANSISTOR MIXER, Model TM -I.
enthusiast.
£11.16.6 Kit
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
recorder inputs. P/B selection.
L38.9.6 Assembled
£28.9.6
roiligtt-
*
Kit
S-33
Send
for full spec. of any model
TRANSISTOR RECEIVERS
"OXFORD" LUXURY TRANSISTOR
DUAL WAVEBAND RECEIVER.
The
S-99
HI -FI TUNERS
Model FM-4U.
Tuning
range
88 -108 Mc's.
Tuning unit (FMT4U) with 10.7 Mc /s. I.F. ([2.15.0
incl. P.T.).
I.F. Amp. (FMA -4U)
ideal domestic
or personal portable
receiver. 10 Semi -conductors. Solid leather
case. Send for full details.
Incl. P.T. £14.18.0 Kit
complete with cabinet and valves
(413.13.0). Total
£16.8.0
TRANSISTOR PORTABLE. Model
OXR -I.
Prealigned I.F. transformers.
6
Printed circuit, 7in. x 4in, high flux speaker.
Real hide case. Very easy to build.
Incl. P.T.
A must for the Tapa
(16.17.6 Assembled
£12.11.0
Kit
Kit
Assembly can be arranged.
FM -4U
AM /FM TUNER. Covers
900-2,000 m.
FM 88 -108 Mc /s. A.M. 16 -SO. 200 -550,
Tuning heart ((4.13.6 incl. P.T.), and I.F. Amp.
(L22.11.6).
Total
Send for leaflets. Assembly can be arranged.
"MOHICAN" GENERAL COVERAGE
RECEIVER.
£27.5.0
Kit
EQUIPMENT CABINETS
Model GC -I U. Excellent
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.
portable
A
large range,
in kit form
or assembled
and finished, available to meet most needs.
Illustrated details on request.
,6
Prices from
to
£8.8.0
(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.
£46.4.0
PUBLIC ADDRESS AMPLIFIER,
PA -I. 50 w. Amplifier, two heavy duty
speakers, variable Tremolo.
Ideal for
use with guitars, etc.
Kit
(74.0.0 Assembled
Legs optional extra 17'6. Set of 4.
£54.15.0
SO W POWER AMPLIFIER, MA -50
A WIDE RANGE OF BOOKS ON ELECTRONICS AND
Ideal for PA work, electronic organs etc.
RADIO. PLEASE SEND FOR LISTS OR PRICES.
¿27.18.0 Assembled
£ 19.18.0 Kit
Many other models covering a wide range of equipment
for HOME, OFFICE or Workshop.
STARMAKER '33. Transistorised PA /Guitar Amplifier.
SEND FOR FREE BRITISH CATALOGUE
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'
American Catalogue sent for I'- post paid
deep. Kit 444.19.0. Assembled 459.10.0 available shortly.
'JIIIIIIIIIIIIIIIIIIIIIIIIIIIII) IIIIIIIIIIII111111I11111111111111111111111111111
To DAYSTROM LTD. Dept. P.W. -12, GLOUCESTER ENG. I
FREE
Please send me FREE BRITISH CATALOGUE (Yes /No)
I
CATALOGUE of the
Full details of model(s)
BRITISH HEATHKIT RANGE
Gladly sent on request
.
..
aasa
NAME
ADDRESS
-------
PRACTICAL
654
December, 1965
WIRELESS
1.
15 x 7 1 1 #fn. A.C.
e VALVE 15 WATT PUSH -PULL AMPLIFIER,
bass and
Mains 200-250 volts. 4 inputs with controls for same andExtra
treble lift controls. Tapped for 3 and 15 ohm speakers.7 gm. P. H.T.
& P.
and L.T. for F.M. Toner aupplies etc.. built and tested.
13/6.
ALL TRANSISTOR
2. CYLDON AM FM PERMEABILITY TONERS FOR manufacturer.
A.M.
OPERATION. Size 2; x 21in. approx. By famous from 1620 ¡Kc /,-5.25
1.F. 470 Ho¡e, F.M.-I.F. 10.7 Me /s. A.M. coverage
216. FREE
diagrams
Circuit
88Mc
/s.
Kc /e. F.M. coverage 108 Mc /4F.M.
4th
and
2nd,
3rd
with Tuner, 1st, 2nd and 3rd A.M. I.F.'e, let,
above are the R.F.
I.F.'s V.H.F. Oso. choke, A.M. I.F. trap. All the
radio etc. The above Items 22.I0.0.
end of an A.M. /F.M. receiver
or
chassis 81 x
3. AMPLIFIER HIT. 3 to 4 watt Amplifier Kit. Comprising
Double wound mains transformer, output transformer,
21 x lin.
etc. Valves 6t'8.
volume and tone controls, resistors. condensen
4/6 P.61'.
ECC81 and metal rectifier. Circuit 1 /6. free with kit, 29/8 plus
RECTIFIER
a
&METAL
VAL ¡VE PUSH-PULL AMPLIFIER
4.
FIER.
T 6
8and mikes.
r L.P. records, musical instruments, all makes of pick -ups
treble
and
bass
Separate
distortion.
total
cent
at
5
per
watts
8
Output
Output
lift control. Two inputs, with contrele for gram. and mike.
transformer tapped for 3 and 15 ohm speech coils. Built and tested.
28.19.6. P. A P. 8 / -.
GEC Choke size 81 x
6. 40W FLUORESCENT LIGHT HIT incorporating
A P. 4;6.
li x lain. 2 bi -pin holders, starter andss. starter holder. 11/8, P.GEC
choke
Similar to
older 17/8.
starter holder,
starter
x Il a 11in.W bin-pin
size
P. A P. 5/6.
Push -pull X
8. OSCILLOSCOPE for D.C. and A.C. APPLICATIONS.
Scan Wave form
amplifier: Fly -back suppression; Internal Time -base
TV line
available for external use; pulse output available for checking
C.R.T.
O/P Tranformere, etc. Provision for external-1 /P P.and
R P. 10 / -.
Brightness Modulation. A.C. mains 200- 250v., 218.18.0. and
TUBE.
VALVES
FULL 12 MONTHS'. GUARANTEE INCLUDING
in metal
7. FIXED FREQUENCY SIGNAL GENERATOR. Crystal controls
ease, size 10 z 6 x bin. Incorporating two FC13 valves. mains transr
former, metal rectifier. choke, indicator lamp, crystal
Originally
components. Modulated and unmodulated output socket.
used for I.T.V. frequencies. Brand new. 89/6, plus 71- P. A P. A.C.
mains 200 -250 volts.
paid.
SILICON RECTIFIERS. 250v. PAN., 750mA. Six for 7/8 poet
9
and
i
S. SencHET MULTI-METER.
0
0 O.P V. on Sboth 3A.C. and D.C.
D.C. current 0- 150mA.
0 -15, 0 -150, 0- 1,000.
21
1
fin
A.C. and eD.0 volts.
Resistance 0-100k O.
Soldering Iron
FREE GIFThfer limited period only. 30 )watt Electric
value 15/- to every purchaser of the Pocket Multi- Meter.
from 174.
9
Cover
Valves rrequired PCF80 and PCC84
BBC and ITA ranges. Also Police, Fire and Taxis, etc. Brand new
by famous maker, 10/ -, P. A P. 3/ -.
8, CHANNEL TUNER
R
12
incorporating
maire transformer, rectifier and condensers. 230/250 A.C. mains
Output; 9v.. 100MA. 10/6 plue 3/- F. A P.
plays 10
11. B.S.R. MONARCH 0A14 WITH FULL FI HEAD, 4- speed,Intermixes
records, 12in.. 101n., or 7in. at 16. 33, 45 or 78 .p.m.
manual play
7in., loin. and 12in. records of the same speed. HasSpace
required
position; colour brown. Dimensions: 121 x 101in.
above baseboard 41in., below baseboard 21ín. Fitted with full Fi
turnover crystal head. 26.19.6. P. & P. 7/6.
10. POWER SUPPLY HIT in metal case. size 31 e 21 x 210.
10
&
TV
12. FIRST QUALITY PVC TAPE
Sin. L.P. 850ft.
9/51in. Std. 850ft.
3in. T.P. 80ft.
.. 11/6
7in. Std. 1200ft.
5in. T.P. 1800fí.
.. 4/3in. L.P. 240ft.
51ín. T.P. 2400ft.
.- 11/6
51in. L.P. 1200ft.
7in. T.P. 36001).
18/6
L.P. 1800ft,
Free.
Post
P. & P. on each 1/6. 4 or more
10 /0
10,6
25/0
82/6
42/6
18. MAYFAIR 5-TRANSISTOR TAPE RECORDER
Capstan -driven, battery operated, 71 and 31 i.p.s. Precision made.
-pull circuit.
Push-button controls. High quality 211n. speaker. kcPushFast
rewind.
/s.
Output: 400 mw. Frequency response: 200 -7,00
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.
etc. Five or six eleCan be used for wash boilers, washing machines, watts.
Size 51 a 11,
ments can be used in parallel to give 250/300
copper enclosed. 2/6 each. P. & P. 1/-. 4 or more Post Paid.
RADIO & T.V. COMPONENTS (ACTON) LTD.
21b High Street, Acton, London, W.3.
Envelope.
All enquiries Stamped Addressed
outside U.K.
Goods not despatched
p.m. Early closing Wednesday
Shop hours 9 a.m.
-6
December, 1965
COMBINED
PRACTICAL
PORTABLE &
CAR
WIRELESS
655
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. ONLY
Ferrite -rod internal aerial
I.F. neutralisation on each
Plus 616 P. & P. Parts
**
*
**
£4.4.O
*
* with
D.C. coupled output
separate A.C. negative
-POWER
* All components,
ferrite rod
tuning
mounted
printed board.
** Operated
from
battery.
comprehensive instructions
** Car
Fully tunable over medium
long waveband.
-to -point wiring diagrams.
aerial socket.
after
service.
* point
Printed circuit board,
printed with
component
list
stage 460 kc /s.
2/6.
stage
& circuit diagram
FREE with parts.
feed back.
and
assembly
SPECIAL OFFER
SUPPLY KIT to purchasers of
"Elegant Seven" parts, incorporating
mains transformer, etc. A.C. mains 200 -250v.
Output 9v, 50mA. 716.
on
PP9
Full
and
and
back
Full
values.
all
-sale
All enquiries Stamped Addressed Envelope.-1
RADIO & TV COMPONENTS
Open 9 a.m.
-6
p.m. including Sots. Early closing
(ACTON)
Wed.
LTD
2IC High St., Acton, London W3
Goods not despatched outside U.K.
Terms C.W O.
FREE -T
THE LATEST EDITION OF ENGINEERING. OPPORTUNITIES
Have you sent for your copy?
ENGINEERING OPPORTUNITIES WHICH IS YOUR
PET SUBJECT?
is a highly informative 156 -page guide to
the best paid engineering posts. It tells
Mechanical Eng.,
you how you can quickly prepare at home
for a recognised engineering qualification
and outlines a wonderful range of modern
Home Study Courses in all branches of
Engineering. This unique book also gives
full details of the Practical Radio & Electronics Courses, administered by our
Specialist Electronics Training Division
the B,f.E.7'. School of Electronics, explains
the benefits of our Employment Dept. and
shows you how to qualify for five years
promotion in one year.
-
Electrical Eng.,
Clvll Engineering,
Radio Engineering,
Automobile Eng.,
Aeronautical Eng..
Production Eng..
Building, Plastics,
Dre ughtomanehip,
Television, ate.
GET SOME
LETTERS AFTER
YOUR NAME!
"ENGINEERING
OPPORTUNITIES"
today-FREE.
EQUIPMENT
Basic Practical and Theme.
tic Courses for beginners in
Radio, T.V.,
Electronics.
Etc.. A.M.LE.R.E.. Cils &
Guilds
Radio Amateurs' Exam.
R.T.E.B. Certificate
P.M.O. Canniest.
Practical Radio
Radio &Television Servicing
Practical Electronics
Electronics Engineering
Automation
INCLUDING
TOOLS!
The specialist Elea
ironies Division of
NOW
offers you a
real laboratory train
int at
home with
practical equipment.
Ask
for details.
BIE.Ta
SCHOOL OF
ELECTRONICS
A.M.I.Mecb.A
A. M. t.
C. E.
A.M.I.Prod.B
SATISFACTION OR
REFUND OF FEE
Whatever reer age or experience, you cannot afford
to miss reading thU famous book. ti sou are earning
less
than FRO a week, send for your copy of
PRACTICAL.
A &1.1.21.1
Please send me your FREE 156-page
"ENGINEERING OPPORTUNITIES"
e.se.
(Write if you prefer not to cut page)
A.M.I.E.R.e.
City & Gelido
Gen. Cert. of Education
Etc, ek.
BRITISH INSTITUTE OF ENGINEERING
TECHNOLOGY
(Dept. SE /2I ), 29 Wright's Lane, London, W.8
THE B.I.E.T. IS THE LEADING
NAME
T
J
ADDRESS
SUBJECT OR EXAM
THAT INTERESTS
ME-- __._........._ .... ...,.._
SE /2I
ORGANISATION.' OF-ITS KIND' IN THE WORLD
PRACTICAL
656
December, 1965
WIRELESS
Offer the Finest Value and
HOME CONSTRUCTORS
value on the home construcWe consider our construction parcels to be the finest
to build the set, you may return
tor market. If on receipt you feel not competent
it as received within 7 days when the sum paid will be refunded less postage.
The "REALISTIC" Seven
Superhet. * 350 milliwatt
* 7- transistor
output into 41n. high flux speaker.
*
All components mounted on a single
printed circuit
THE "SKYROVER" RANGE
GENERAL SPECIFICATION
Full madboard.
2 diode superhet, 6 waveband portable
turn and long wave
receiver. Operating from four 1.5 v, Loch batteries.
Plastic
cover.
*
The SKYROVER and
-941 M
cabinet with carryShortnWavebancover
ranges. 13M,
ing handle, size
and also 4 separate switched band- spread
accuBlue/
for
Tuning
10
x
38ín
7
x
Band
Spread
with
16M, 19M and 25M,
--and tuning heart
Grey or all Grey.
rate Station Selection. The coil packwired
and tested.
Socket for car
*
is completely factory assembled,completed
in
I.F.
*
aerial.
frequency 470 Kc /s.
threeremainingrm our easy Lob òllow tage y stage
* Ferrite rodOperates from PP) or
instructions.
internal aerial.
battery. * Full data supplied
SKYROVER Mk edgewise similar
NEW
A simple additional circuit
All coils and I.F.'s etc. fully wound ready
cabinet,
coverage
redesigned
with
supplied
Now
assembly. Any outstanding
immediate
for
cabinet.
(ncluding
11ÓÓ/1á950M, a
controls, black and chrome plastic
receiver.
1500 M. Light programme).
Size 10 x 61 x 311n. with carrying handle. el19.g Post
(An be built for
V
5
Al) components and defor
built
be
now
('an
4/6.
tailed construction data.
dep and ll months at 15)9. Total Post
H.P. Terms:
PP9 Batt. 3/9. Data and Instructions
P. Price 27/separately 2/6. Refunded if you purchase
Only10/-extra F:.7(
the parcel. All parts sold separately.
This conversion Is suitable The SKYROVER DE LUXE
for both models that have Tone
constructed.
lin.,scoverred REALISTIC Seven DE LUXE
already been
size,19 x 6} x and
abinetincorporated
o
In a wCircuit
carrying With the same specification as standard
a washable material with plastic trim
Data for Receiver 2/6 extra. with
model -PLUS a superior wood cabinet
fitted.
socket
aerial
Car
Refunded if you purchase the handle.
Terms:
3a3)-19/2. in contemporary styling with full vision
H.P.
now be built fora
parcel. Four U2 batteries */3 Can
at
ONLY £1 EXTRA
extra. All components available Post 5,£10.19.6 aotal R.P.P. 19)2. circular dial.
7
transistor plus
1
---
.
Ill
-The
f .19. 6
Li
separately.
STOP PRESS ITEM!
363 TAPE DECK
The Very Latest MAGNAVOX -COLLARO
track heads. Features
i track or
3 Speed model -11, 31, 71 i.p.s., available with either and
new 4 pole fully screened
rewind;
forward
include: pause control: digital counter; fast
deep below unit
Size of top plate 131 x llin. x 51ín. fully
induction motor; interlocking keys.
guaranteed
plate, For 2001250v. A.C. mains, 50 c.p.s. operation. New. unused and
LASKY'S PRICE with } track heads £10.10.0 pacffinge 7/6
extra
LASKY'S PRICE with }track heads £13.19.8
TAPE DECKS
STUDIO
COLLARO
STOCKS:
LIMITED
I
}
200/250v. A.C. mains, 50 c.p.s. model -with
Carriage and packing 7/6 extra.
213.19.6.
track heads 210.10.0: with
}
track
heads
ELIZABETHAN LZ27 PORTABLE TAPE RECORDER
unused and fully guarSpecial Bargain Offer-brand new,
34 i.p.s.: 2
anteed. Brief specification: 2 speeds-7i and
track; 31 watt output; inputs for mic. and radio; outputs
or monitor; built in
for ext. speaker and additional amp.
7 x 41n. speaker; tape position and record level indicators;
also
fast forward and rewind. Volume and tone controls A.C.
For 200/250v.
superimpose facilities. Takes 7in. spools.
mains. Attractively styled cabinet with carrying handle
Complete
detachable
Price27 Gnsl
m tape an empty spool 1 Maker's
LASKY'S PRICE 18 Gns. and Packing 10/-
25.19.6
25.19.6
lin.
Message tape, 150ít.
Message tape, 225ít
Message tape, 300ft.
Triple play, 600ft., Mylar base
Triple play, 900ft., Mylar base
Double play, 1,200ft., Mylar. base
An.
Long
81n.
Sin.
Sin.
S }in.
On.
Sin.
Ilse.
play, 900ft., Acetate base
Standard play, 600ft., PVC base
Triple play, 1,800ft., Mylar base
: }in. Double play 1,800ft., Mylar base
£5.19.6 carriage
n
p!a
£6.9.6 5 exckitrga.
Famous Amoebae Brand -Fully Guaranteed
54in. Ling play. 1.20011., Acetate base
8
54in. Standard play, 850ft., PVC base
4 1
51in. Triple play, 2,400ft., Mylar base
7
,
Acetate
....
...,
....
base
12
11
45
10
7in.
7in.
Standard play, 1,200ft., Mylar base
10
71n.
Double play, 2,40011., Mylar base .... 25
8
85
22
Standard play,
1.200ft.,
Long play. 1,800ft., Mylar base
U.H.F. TUNERS
LASKY'S PRICE
15
17
15
7in.
stock the complete range of Sinclair
Super-miniature Kits.
59/6
THE MICRO -6 pocket radio
49/6
THE SLINLINE pocket radio
£7.19.6
THE X-20 Amplifier
19.19.6
Ready bu It and tested
£5 19.6
'111E X -10 Amplifier
16.19.6
Ready Built and Tested
27.19.6
THE X-20 Amplifier
1,9.19.6
Ready built and tested
See our Practical Wireless November '65 advertisement for fuller details.
Only a few available. Complete
with PC86 and PC88 valves. We
regret no circuit or data is available. Knobs included.
GARRARD AT5 AUTOCHANGERS
INTERNATIONAL TAPE
2fist
SINCLAIR MINIATURES
UA16 9 v. battery model
ÚA20 4 speed mains model
Add 5/- carriage and packing on each
SPECIAL OFFER!
19/6
We
AUTOCHANGERS-BRAND
mains model -brand new and fully guaranteed.
LASKY'S PRICE with mono crystal cartridge
LASKY'S PRICE with stereo cartridge
29/-
2/°6! t
LASKY'S PRICE
STEREOPHONIC FILTER. This is aa
frequency divider/mixer for use with
Stereo amplifier. Its function is to combine
a
the bass frequencies up to 300 c.p.s. into
single bass speaker for both channels and to
divide the frequencies above 300 c.p.s.Itinto
can
two separate mid /top range speakers. for
a
also be used as a 300 c.p.s. crossover
mono system. 1511 imp. Rated at,25 watts
(British). In wood case 10 x 41 x 3in. New
LASKY'S PRICE
REVER PR ICES EW
Brand new and fully guaranteed-complete with cartridge
and stylus.
£4 9.6
ÚA14 4 speed mains model
£4.19.6
ÚA16 4 speed mains model
4
HALF SEITION CROSSOVER.
1511
For use with bass and treble speakers.
at 25
imp. to crossover at 750 c.p.s. Rated
watts (British). In wood case 61 x 4} x 4in
New and unused.
X111750
and unused.
i
B.S.R.
GOODMANS OF ENGLAND
CROSSOVER UNITS
..
....
....
12
19
15
Long play, 1,800ft., Acetate base
7in.
58
7in.
Triple play, 3,600ft., Mylar base
P. & P. 1/- extra per reel; 4 reels and over Post Free
7,9/i6
ost
ii.
GORLER UT 340 FM/VHF
TUNING HEART
to 108 Mcls.
Permeability tuned -covering 87
For use with one ECC85 valve. In metal case.
size 3 x 21 x 11in. Circuit supplied.
LASKY'S PRICE
ECC85 valve 91- extra.
19/11
LASKY'S FOR D.I.Y. CONSTRUCTION BARGAINS
December, 1965
PRACTICAL
WIRELESS
657
Service in Great Britain to both
& HI -FI
LASKY'S'
ENTHUSIASTS
TAPE RECORDERS . RECORD PLAYERS . AMPLIFIERS ETC.
COMPLETE MONO STEREO SYSTEMS TO YOUR SPEC.
NEW COMMUNICATION
RECEIVERS
MODEL KT 320 KIT
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
Supplied to sub- aeeeoebliee for easy building. Covers
range From 640 %c /s to 30 Mc /s. Ham Band is provided 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.
25 GNS.
LASKY'S PRICE
POST
Also available ready ballt end tested 29 ene.
H.P. Terms available.
a few avallablegt'1
ae odvertieed June '60.
MODEL HE30
33
LASKY'S PRICE
H.P. Terms available.
GNS.
MODEL HE40
£5.19.6
&
P.
THE LATEST ''KUBA"
IMPORTED AM FM
STEREO RADIOGRAM
b1111111:''
CHASSIS
long medium and short waveband cover-
age plus VHF/FM. Piano key wave.ebangeSeparate 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
carriage & Insurance 12/6 extra.
GNS.
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
use to the most expensive electric cookers.
available-brand new and unused-at well belowforproduction
cost.
3
typal
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
Covers medium wave band and 1.6-4.4 Mo /s., 4.811.0 Mc/a, 11.0-30.0
separate switched
band epread wages Controle Include B.F.O. Sensitivity, 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.
Mc/e.
LASKY'S PRICE
19
H.P. Terms 84.0.0 dep. and
MODELHE80
in
GNS.
months at 11.12.0.
Total H.P.P. 221.12.0.
a'll'er sensitive
11
14- °a°°
communication
receiver.
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.
trcq. range
it
and voltage regulated powerpack. "
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.
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 heating appliances as well as tape recorders, radio., lights, eto. Easy to set.
lln. dial. Overall else 6 x 31 x 2fin.
35/-
Poet 2/6.
LASKY'S PRICE
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
Post 2/8
price 59/6
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
TRANSISTORS new & guaranteed
P.
do
P. 2/8
TRANSFILTERS
BRUSH CRYSTAL 00.
GET SI, GET 55. GET S6, 2/6: 873A, 874P,
TO-01B 465 kc/s. f 2 kcfs.
3/8; 0C45 0071, OC81D, 4/6: 0C44, OC70,
TO-01D 470 kc/s, ± 2 kc/s.
076, 0031 (match pair 10/8) 5/8; AF117,
±
7/6 HACH
TO-025
465
kc/s.
1
kc/s.
R$1.
LASKY'S PRICE
GNS.
0075, 0C200 6/6: 0C42. 0C43, 0073
TO-02D 470 kc/s. 1 kc/s.
H.P. Terms 212.19.0 dep. and 11 monthly payment§
0082D 7/6.00201.0020415/ -; 00205, 0C206
TF-0113 465 kc/s. 2 kc/s.
Poet 64.
of 24.18.0. Total H.P.P. 288.17.0.
0028
18/6;
24/8.
TF-01D 470 kc/s. ± 2 kc/s.
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.
59
BY
tt
LASKY'S FOR SPEEDY MAIL ORDER SERVICE
December, 1965
PRACTICAL WIRELESS
658
NEW!
NEW!
Just published end of October
TAPE
RECORDER
SERVICING
Packed with concise
servicing data and facts for
day-to -day use
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
A book to save
you time and
make you profit
concise service data, including
circuit diagrams and numerous layout diagrams and views
of mechanisms and adjustments, 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_
...
the 'gen' at
your fingertips
in one
authoritative
volume !
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,
Makes covered Cossor, Dansette, Defiant, Dynatron, E.M.I.,
from 63
Editor, Ekco, ElizaManufacturers
bethan, Elpico, Elpico-
include..
Geloso, Ferguson,
Ferranti, Ferrograph, Ficord, Fidelity, G.B.C.,
G.E.C., Garrard, Geloso, Gramdeck, Grundig,
H.M.V., Hagen, Kolster- Brandes, Korting,
Peto- Scott,
Murphy,
Magnavox, Motek,
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.
rom your bookseller,
POST FORM TODAY!
or:-
NO SALESMAN
WILL CALL
Sevenoaks, Kent.
To: Odhams Books, Dept. S.F.3, Basted,TO
PURCHASE, "Tape
me, WITHOUT OBLIGATION
book in good condition,
Recorder Servicing Manual ". I will either return the
of 191- eight days
payment
down
send
OR
days,
eight
carriage paid, within
/- each. ALTERNATIVELY,
after delivery, then five monthly instalments of 10charge
days after delivery.
eight
postal
a
small
plus
63/of
I will send cash price
am
/BY TERMS.
Delete words NOT applicable: I wish to pay CASH
resident; (d) single
(a) houscowner: (b) tenant in house or flat; (c) temporary
(e) married; (f) over 21; (g) under 21.
Please
send
1
Your Signature
guardian)
(lb you are under 21, please obtain signature of parent or
BLOCK LETTERS BELOW
NAME
Full Postal
ADDRESS
SF,3.
The book that can repay its
purchase within a few hours
December,
1965
PRACTICAL
WIRELESS
659
BAKER LOUDSPEAKERS
DESPATCH- TODAY ? -PHONE- R.C.S.!
TUBULAR
1/860v 2/2/350v 2/3
4/360v 2/3
8/460. 2/3
18/450v á/32/460v 8/9
25/26. '1/9
TUBULAR
100/25.
.
60/60, 2/-
together
SINGLE PLAYERS
B.S.R. GU7 auto stop
RSA. Junior with lep. P.U.
14.17.6 P.P. 2/6
19.7.6 P.P. 2/6
1516
/tin.
1816
1519
181-
I'?in.
201.
20/6
)kin.
in.
2 4in.
2341
10w. Menti-ratio Push Pull. 18/6.
Standard Pentode 5/6. Mis. bal. o-p
lin. sq. 31/6
WEYRAD
6856
6AT8
6BA6
6BE6
SAS
6J5
6J6
6271;
BKB
8117G
BK86
65731
day Guarantee
90
et- E13/241
5/-EBCBl
5/-EBF80
8/-ECH42
8/- RCH8I
6/- ECL80
6/- 12AU7 6/- ECI.82
9/-11AX7 7/-EF162
4/- 121E7
5/. 2E183
6/- 12K8 14/. EF88
8/-6Q711
8/-68\7
3/-6V6G
7/-8X4
7/- 6X5
8/- 12AT7
7/- 12Q7
5/- 35133
3/- 35Z4
5/- 951
5/- DA1-96
8/-D1096
5/- DK96
8/-DLO6
71- EPOS
9/- ELS4
5/- F.V51
2/- E 1(86
8/- E'L40
8/-EZe0
8/- RZ81
8/-MU14
0/-NABCAO 5/- PC97
6/- EH91
4/- PCC84
8/-'PCL54
6/-PL01
6/-PL83
9/- PY80
9/- PY81
9/- PY82
10/- 81.61
7/. U12
7/- UBC41
10/- UBCBI
5/10/-
9/7/8/7/-
8/7/S/6/5/9/-
8/- UBF89
7/- UCA81
9/- UCL82 10/91- EF89
5/.
5/- EL41
9/7/-UY41
6/.
7/- UY85
7/7/. 111.79
7/.
7/. VR150 ^/8/- W8]
6/-
B.T.H. TAPE MOTORS 113 v. A.C.I
20 w. 12/8 pair. for 200 -260 V. (in sertes)
RETURN OF POST DESPA ICH
1
1
trans 6/9
*RADIO BOOKS* (P.P. 9d.)
Valves, Diodes,' Transistor equivs,
TranslstorAudloAmplitier Manual 10/6
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
PSO
.
COILS
.
.
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
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/C tape up to 60, 29 ¡8
'25.,
pp
AUTOTRANBFO RMERB
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
I.F. TRANSFORMERS 7/6 pair
New R.C.S. VALVES
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
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. 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/.
17/6; Ox4in. 21/ -. Book 2/ -. 3 ohm OPT 10/8
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
465 K/s Slug Tuning Miniatore Can, 8 u 1 }in. dia.
High Q and good bandwidth. Data Sheets,
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.
Ferrite aerial 12/6. Ow. P50 /1AC, 5/6; 1st
P0ri/v2CC
P5Ó/3CC P;
Tr /ansLFDT4, 9/6;
Printed Circuit 9/6; 35 ohm Speakers,
51n.
condenser with trimmers, ferrite aerial, Tuning
dial, Mallard tramiators and power pack components, 13.15.0. Eagle 00402 coil set only, 24/6.
5Z4
7/-
12/-
2916
DOUBLES 42/6. PP1+PP1, PP9 +PP9, PP11
(4 4 ; +4 ;1. Sine as batteries. Also min. 9v. 19/6.
4413
PW TAPE RECORDER TUNER
5E3
8/-
11/8
TRANSISTOR MAINS
ELIMINATOR PP1-6v. PP9.9v.
37/9
All components specified Eagle H402 transistor
coils. 3 455 ko I.F.e and oscillator coil, tuning
5114
7/8
5/6
32 +32/850.
82+22/450.
8+18/450. 879 50 + 60/350v
16 +18/450. 4/3 84 +120 /350v
82 +32 /SSOv 4/6 100+200/275.
,
CRYSTAL MIKE INSERTS
dia. x lin.. 6/6; BM8 1 x }in..
ACOS MIC. insert 111n. die. x }ln.. 7/8;
TANNOY CARBON MIKE complete, 8/8
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,
Test Prods, 2/9. Set Trim Tools, 6/8.
Neon Mains Tester Screwdriver, 3/.
/..
MWtieore Solder, 6d. yd. Dispenser, 25/6.
354
9/-
12/-
10+ 16/500v
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.
1 1in,
384
18 /800.
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,
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
IR5
CAN TYPES
8 /800.
0.1, 2/ -; 0.25, 0.5, 8/-.
2,000v. 0.005, 0.01, 0.02, 2/6; 0.05, 3/6.
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
114
2/8
2/8
2/6
3/8
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.
Itrnetmns
enable as-
185
2/-
250/25v
500/15v
1,000 /15v
8 +8 /460v
PAPER TUBULARB
perfectly.
Special in-
lin.
-in.
lin.
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.
NEW ELECTROLYTICS FAMOUS MAKES
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
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
Long
6
K
L.B.
opiudles.
clime to
3/..
Tracks
Midget
2
Meg
4/8
Stereo LIB 10/8: DP. 14/6
lm log . lm A log. 716
D.P.
i
semi -ati
paced
40 yds. 17 /6.
60 yds., 25/
lis.
6d . y d.
Ideal 625 dues
Low loss 5,111
100ft. 50,1 Mc,al
C.D.F
/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.
BALANCEDTWIN FEEDER. 66. yd., SO or 300 ohms
TWIN SCREENED. 1/- per yard, 80 ohms only.
"INSTANT" BULK TAPE
AND RECORD HEAD
ERASER
10
15
watt
Send remittance and postage, no C.O.D.)
11.5
1
watt}
watt)
to
B.! ohm
:5
W
WIRE -WOUND RESISTORS
10 ohms -4,800 ohms
<
1/9
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
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.
K
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
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lm
6/6;
11 x 71n.. 7/6; 13 a 9in., 9/6; 14 e l
13,0., 15 / -; 11
áls.. 0/8.
e.,e.a. 12 o I.2in., 5/6; 14 x Sin., 4/6:12 x bin
7m.. 2/9; 4 x din., 2/ -; d x Co.. 1/6.
13 x
DEMAGNETIZER 200/250.. A.C. 351.
Panel. 18
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P.P. Charge f'6 Full list It -, C.O.D. 2'6 extra
ever y purchase (Export;
.
-
5
RADIO COMPONENT SPECIALISTS
Written
with
i .Jarantee
.
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
20"x, 4d.; l; w., 8d.; 2 w., 1 /..
l ' I
HIGH STABILITY l w., Ivá, 2 / -. Preferred value,
ln ohms to 10 meg. Ditto 2
to ohm. to 22 nieg., 9d.
,
THE
.
'
CALLERS WELCOME
337
WHITEHORSE ROAD
WEST CROYDON
Telephone
1665
Buses 133, 68 pass door. S.R. Stn. Selhurst
December, 1965
PRACTICAL WIRELESS
660
WHAFtF.dE,p4
E RANGE
were,Wharfedale
If
it
Impossible?
results.
good
obtain
and
pipe
Build a loudspeaker system in a concrete
would not recommend it. The fact is that experimental results of this type of enclosure were so successful
kits
that Wharfedale have produced an inexpensive kit especially for the Do -it-Yourself enthusiast.willThe
need a
come in two sizes-for 8" or 10" speakers and cost £5.0.0 and £6.5.0. In addition you
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.
MFG Princ ole of construction of
The top is fitted with a loose weave acoustic material.
system In concrete column
ONE TO BUILD YOURSELF FROM THE
Anomie Cloth Cover
Foatn
Houk Gasket
a' or 1t
RECOMMENDED UNITS FOR THE WHARFEALE CONCRETE COLUMN AID
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down to 40 c/s. Power handling capacity 6 watts.
57.0.0 (Tax Paid)
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A 10' speaker with double diaphragm, roll surround and powerful
magnet. This unit gives frequency response down to 30 c /s. Power
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WHARFEDALE WIRELESS WORKS LTD.
IDLE
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POST THIS COUPON TODAY;i
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for idly illustrated simple to fallow construction folder
Positioning Blockt (3)
NAME..
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But with Tuning Vents
Dept.
ADDRESS
WHARFEDALE TOWN
COUNTY.
P
PRACTICAL
WIRELESS
DECEMBER
VOL 41
1965
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 commercially 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, transmitters 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 3
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.
page
662, 692
by Mike Fisher
664
by R. F. Farley, G3SSJ
670
by A. Clement
672
by Alan Ford
676
by H. T. Kitchen
677
by John Guttridge and David Gibson, G3JDG 680
by F. G. Rayer, G3OGR
684
by J. G. Ransome
688
by, R. Leyland
690
by A. J. McEvoy, B.Sc.
694
by H. W. Hellyer
698
by Henry
705
by D. Bollen
706
by J. B. Willmott
713
721
All correspondence intended for the Editor should be addressed to: The Editor, "Practical Wireless ", George Newnes
Southampton Street, London, W.C.2. Phone: TEMple Bar 4363. Telegrams: Newnes Rand London. Subscription rates,Ltd., Tower House,
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
662
NEWS ANC..
Competent Constructors
WHEN I first read R. A.
Packer's letter in the October
issue of PRACTICAL WIRELESS, I
felt rather annoyed. On reflection, 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 Constructor have done me the
honour of accepting and publishing 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.
ELECTRICALLY OPERATED TELESCOPIC MAST
A.
Clark
(Engineers)
of Binstead.
Masts a new series called
"Super E ". The unique feature of these latest designs
is that they are arranged to
be powered from a 12V
supply which most conveniently 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
mounted
neat
dashboard
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 electrical connection it is arranged that the mast cannot
remain extended if the ignition switch is turned on.
Nuneaton,
Warwickshire.
Electronic Developments
I MUST disagree with R. A.
Packer's remarks on the future
electronics
in
developments
(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 semiconductor 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 " incompetents" of today are still
enjoying themselves with their
" obsolete" valves and transistors.
Miniaturization is all right for
manufacturer
the equipment
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.
N.
Isle of
Wight, have recently added
to their range of Telescopic
Ltd.,
*
CARRIER FREQUENCY IMPROVEMENT
.
In 1945 the BBC inaugurated high -precision frequency control
of its 200kc's transmission of the Light Programme from
then
Droitwich. The long -term frequency stability, which was
1963 and
within I part 10 , was considerably improved ininJanuary
IO''.
since then has been maintained within 5 parts
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 available for 21 hours daily from 0400 to 0100 G.M.T
"WHICH ?" REPORTS ON RADIOS
in
The September issue of "Which ?" reports on 24 v.h.t. radios ranging
price from L 1 to £42. The panel of experts tested the radios for sound
signals
quality, freedom from interference, ability to receive weak
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.
663
..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 Department, 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 "Lektrokit" plate. The construction is in
the form of an open rectangular
tube so that the natural "chimney effect" assists the cooling of
the heatsink. The shunt- stabilised 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
x 311- 5,-in. x 44.in. and the price is E12.
;in.
more News and Comment
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 speaking, 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, avoiding 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
664
PRACTICAL WIRELESS
A Transistorised L.C.R. Bridge
Part One
By Mike Fisher
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
connected across the
a moving -coil meter,
remaining pair of arm junctions.
The method of operation of the circuit is to
Fig. I:
Simple
Wheatstone
bridge circuit.
December, 1965
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
or. to put it another way, when
when
Rx
RV
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 scalea
of RV is then calibrated in ohms it becomes
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
was
52652 it could be seen that the value of Rx
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
It is therefore general 'practice to
to 1Okft.
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
December, 1965
PRACTICAL
WIRELESS
readings
from 0
to
10MÍ2. To prevent excessive current flowing on
the lower ranges, resulting in overloading of
the supply, a limiting
resistor is connected in
series with the supply
and also acts as a semiautomatic sensitivity control by voltage divider
665
Bridge
Range
Switch
Position \
0-10rc
0-I00Í2
2
0-1kÍì
3
action.
0-10kí2
4
It may be noted that
0- I00ki2
5
several
bridge circuits
0-1 Meg
6
that have been published
0 -10Meg
7
in the past have made
use of a.c. as the power
source for the WheatTo detector
stone bridge circuit, thus
Seven range Wheatstone circuit used on prototype
enabling headphones to
instrument.
be used as the detector
in common with the capacitance and inductance
impedances against one another. In this particular
measuring bridge circuits. The disadvantage of this
case, regarding the chain Rl and Zs and the chain
system is that if the resistance to be measured
conR2 and Zx as voltage dividers again, it can bet
tains any reactive components inaccurate readings
Rl
R2
will be obtained. It would be almost impossible,
=
.
Lt must be
for example, to measure the d.c. resistance of a seen that at balance
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
Fig. 3:
and Rx represent the series combination of
Simple De Sauty
impedance of the unknown capacitor, Rx not, of
bridge circuit.
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
tuning coil or choke with such a circuit. D.C. has
equation. In practice the bridge is balanced by
therefore been used to energise. the Wheatstone
means of both the variable resistor Rs and the
bridge in the instrument described in this article.
main balance control Rl, a null being obtained in
Several bridge circuits exist which may be used
each case.
for the measurement of capacitance but
that
At balance it is then possible to read off both
known as the De Sauty
is generally the most
favoured.
To detector
The circuit diagram of
a simple De Sauty bridge
is shown in Fig. 3 and,
as can be seen, the basic
cx
Bridge
Switch
configuration is similar
9kC1
Range
Position
to that of the Wheatstone circuit. Each of the
0-100µF
`-a )
lower bridge arms is re0-IOµF
Z
placed by a capacitor
0-IµF
3
and series resistor, how0-0IµF
4
ever, and the bridge is
0-0.011,F
energised from an a.c.
source.
In the De Sauty or
any
other
bridge
that
measures capacitance it
is necessary to balance
0-I000pF
0-100pF ;
To detector
Fig. 4 Seven range De Sauty circuit used on prototype.
S
6
:7
December, 1965
PRACTICAL WIRELESS
rR2
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
Rx =Rs.
and
detector
Rx =R1.
and
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
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".
In the Hays bridge a standard capacitor is
connected in the opposite arm to the unknown
Again the bridge works on the
inductance.
As most
principle of balancing impedances.
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 components 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
n
Lx
Rs.
If the frequency of the energising source is
accurately known the loss angle of the inductor
can be worked out from:
tan
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 calibrationis
of R1 as was used for the two earlier bridges.
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 circuit used in the instrument that forms the basis
Switch
Bridge
of this article is shown
Position
Range
in Fig. 6.
The circuit wiring and
100µH
components of a practi2
I mH
cal bridge or any other
3
IOmH
piece of electronic equip 4
I00mH
must inevitably
ment
5
H
inducstray
contain
6
10H
tances and capacitances.
7
1001-1
If 100% accuracy of
readings on all ranges is
to be obtained these
strays= must be either
I
To
Flt. 6:
detector
Seven range
Hays circuit used on prototype.
1
6.28.Rs.Cs.
It may be noted that the Q of an inductance
I
KR
S-
December, 1965
PRACTICAL
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 consideration. 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 minimum, 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 equipment.
WIRELESS
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.
668
PRACTICAL
not otherwise be carried out. The -major disadvantage 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 considerable 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, /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.
1
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 combination 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
December, 1965
WIRELESS
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
December, 1965
i
PRACTICAL
NEXT MONTH
WIRELESS
669
in PRACTICAL WIRELESS
i
16 -PAGE
Pull -out Booklet
SHORT-WAVE DATA
Another vital Booklet packed with at-aglance 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
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ISSUE
ON SALE
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4
PRACTICAL WIRELESS
670
December, 1965
by R. F. Farley, G3SSJ
A Thumbnail History of Radio
PART
3: WIRELES1
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 improvement 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 amplification 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
the
"'R" type valve and the " V24", although
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.
FOR ENTERTAINMENT
possible due to the ionisation effects although grid
current was considerable.
On the field of battle the problem of transporting 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 broadcasting was started experimentally by the Westinghouse 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 locating 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
in
after graduating in Stockholm he settled of
America, where he later became chief engineer
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 development engineering because of its mechanical
at high
problems, for its armature had to rotate
speeds and its mass was great. This meant that
bearing wear would be very high unless the
of
bearings were machined to fantastic degrees
accuracy. There was also the problem of centrifugal force. Since frequencies of many kilocycles
were required the armature had to be driven
no
through a step -up gear -box; there were then
motors to operate directly at these speeds. There
alteris an excellent example of Alexanderson's
a
nator in the Science Museum, together with
wonderful collection of historic wireless instru-ments.
In America the first regular broadcasting station,
KDKA, succeeded the experimental station of the
December, 1965
PRACTICAL WIRELESS
671
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 Northcliffe 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 throughout 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 manufacturers. 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.
Fig. 3: The Reinartz circuit.
References were required before licences could be
pany started a regular series of broadcasts in
granted to "approved persons " for experimental
February, 1922, which are unique in broadcasting
purposes only, although the Wireless Society of
London fought hard for better facilities. The history. From a hut at Writtle the brilliant Peter
Eckersley, supported by a wonderful young team,
Wireless Society of London later became the
showed what the microphone could do. The power
R.S.G.B. Amateur transmitting licences were also
issued for powers generally not exceeding 10W.
at Writtle was only 200W and even this was
almost strangled by legislation.
Some amateurs found it necessary to broadcast
Following each three minutes of broadcasting a
frequent programmes of gramophone records.
period of three minutes' silence was demanded, so
Particularly well known at the time was Station
the obvious choice of material was gramophone
ZAZ at Guildford, owned and operated by
records. But enterprise thrives in the face of
Mr. William Le Queux, the novelist. Less
fortunate amateurs contributed their skill to ZAZ, adversity and one evening Eckersley began improvising in fropt of the microphone. He was
which provided them with an outlet they could
immensely witty and his inventiveness enabled him
not afford themselves.
After a short time the broadcasts from Chelms- to use the absurd restrictions to advantage. Before
long the whole staff at Writtle were contributing
ford were banned by the G.P.O. because they were
interfering with cross -Channel air communication, programme material of a largely impromptu
nature. At the end of every broadcast Eckersley
but after further negotiations the Marconi cornimprovised 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 oldtimers. 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 provinces 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
l
lOQ9o0,
.9000
hand. Its prime object was public service. Its
Fig. 2: The Armstrong "Super Regen". Used by the more
first Director of Programmes was Arthur Burrows,
adventurous to receive weak amateur transmissions
a man of serious temperament, which distinguished
below 200m.
-continued on page 675
-
--Y
PRACTICAL
672
December, 1965
WIRELESS
Guitar
Magne tic
Pick-up
Unit
A
BY
A. CLEMENT
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 whenconsidering the coiled string numbers 3 to 6 tape
wound type are recommended.
Magnets
These magnets, obtainable from any good ironmongers, are known as Eclipse " button type " the
size used is in fact the smallest in the particular
range. See Fig. 1.
Fig. I:
Eclipse
Details of the
magnets
as used in
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.
"button- type"
the
pick -up.
Oa. .V'shaped
notch
hole
Fig. 3: Coil formers showing
Base
Perspex or similar plastic }in. thick is used for
the base and the holes for mounting the magnets
on
are drilled as shown in Fig. 2 and countersunk
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
in
fastening ensures that the nuts are held locked for
place. A suitable adhesive could also be used
mounting the magnets, although this means has not
been tried.
2%.
i-
11/2; dia.
holes
_Or
-
.-`l
1/8' thick
f g. 2:
terminals
board
Drilling details of the }in. thick plastic used for
the base.
"v"
Small
hole
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
small
placed in position and wired in series. Twoused
to
brass terminals cemented to the base are
the
anchor the two free ends of the windings acid
lead to the amplifier is taken from these two points
through the hole in the cover.
December, 1965
PRACTICAL WIRELESS
LAFAYETTE HA
673
63
NEW MODEL!
LAFAYETTE HA -230 AMATEUR COMMUNICA-
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
TIONS RECEIVER
Supersedes model HE -30. 8 valves
+ rectifier. Continuous coverage
on 4 bands. 550 Kc/s-30 Mots. IncorpDora tes 1 RF and 2 IF stages, Q
Multiplier, BFO, ANL, 'S' meter,
electrical
Aerial trimmer, etc. Supplied brandread,
new and guaranteed.
for full details.
Also available in Semi -K
m25 Gn98AE
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,
OS /8B /U OSCILLOSCOPES
solid state power supply, adjustable squelch control, slide rule
High quality Portable American Oscilloscope.
dial, built In 4in. speaker and front
3in. c.r.t. T/B 3c /s-50 kc /s X Amp: 0 -500 kc /s
panel phone jack. 220/240v. A.C.
Y Amp: 0 -2 Mc/s. Power requirements 105 -125v.
Supplied brand new and guaranA.C. Supplied in "as new" condition, fully
teed. 19 Gns. Carr. 10 / -.
tested.
£25. Carr. 10/ -. Suitable 230/115v. TransTE-22 SINE SQUARE WAVE
former. 15/8.
AUDIO GENERATORS
CLEAR PLASTIC PANEL METERS
Square: 20pc.ps to Kc/s on 4Ou put
First grade quality. Moving Coil panel
meters
available ex- stock. S.A.E. for illustrated
imp. 5000
leaflet. Discounts for quantity. Available as
ohms. 200/
follows. Type MR38P 1 21/32in. square fronts,
240 v. A.C.
,,
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2mA ..
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/8
GuaranBands 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 /
4
,
..
IOmA
50µA
1000.A
200µA
500µA
.. 32/8
.. 29/8
.. 27/6
.. 25/-
50-050µA..
100 -0 -100µA
S0
ÁaPA
29/6
27/6
22/6
ÓmA ..
100mA ..
150mA ..
200mA
.300mA ..
500mA
750mA ..
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1
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22/6
..
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-0-1mA
1A. DC
2A. DC..
22/8
.. 22/6
.. 22/6
.. 22/8
22/6
22/8
22/6
22/6
22/8
20V. DC
1ÓÓV
DC
150V. DC
300V. DC
500V. DC
750V. DC
15V. AC
50V. AC
150V. AC
300V. AC
500V. AC
22/8
22/6
22/8
22/8
22/8
22/6
22/6
22/6
22/6
.. 22/6
22/8
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POST EXTRA. Larger sizes available -sendMeter
r lists.
ILLUMINATED "S" METER
1 "/ ,m.
front. Cal. in S units.
6V. lamp. 29/6. P.P. 1/ -. Ditto Vhein.square
square. 39/8. P.P. 1 /-.
AVOMETERS
TRANSISTORISED
TWO -WAY
TELEPHONE
INTERCOM
Supplied
Operative over amazrecondiingly long distances.
tioned,
Separate call and press
guaranto talk buttons. 2-wire
teed perconnection. 1000's of
fect.
applications. BeautiModel D,
fully finished in ebony.
£8.19.8.
Supplied completewlth
Post & Ins
batts. & wall brackets.
5/ -.
7 gus pair. P. & P. 5/ -,
ERSKINE TYPE 13
DOUBLE BEAM
OSCILLOSCOPES
Timebase 2 e /s:
750 kc/s. Separate
Y1 and Y2 amplifiers. Up to 5.5
Mc /s. calib at 100
kc /s. and 1 Me/s.
110/230 v.
A.C.
Guaranteed
fect. 127.10.0.perCarr. 20/-,
MINE DETECTOR No. 4A
Fully portable. Completmetals.
instructions. 39/6 each. e Carr.
10/-. Battery 8/8 extra.
MAGNAVOX
363
TAPE DECKS
New 3 speed tape deck. supersedes old Collaro studio deck.
2 track, 210.10.0.
4 track, £13.10.0.
Carr. Paid.
-'
.222/6
10V. DC
teed. £15.
Carr. 7/8.
LAFAYETTE
NUVISTOR
LEADER LSG -I0
GRID
R.F.SIGNAL GENERATOR DIP
METER
120 Ke /s-260 Me/s on 6 ranges. Compact true one
Variable R.F. and A.F. outputs. hand operation.
Large clear scale. Size 7} x 105 x Frequency range
4}in, 200/250v. A.C. operation. 1.7- 180Mc /s. 23Ov.
Brand New. £12. Care. 7/6. AC operation.
Supplledcomplete
with all coils and
TWO-WAY RADIOS
I
Instructions. 612,10.0. carr. 5 /-.
Superb quality. Complete with all accesMODEL TE-12
sories and fully g't'd.
3 Transistor
6/30//120/600/1
27.19.8 pr.
4Transistorllgnspr.
9Transistorl9gnspr.
10 Transistor
pr.
Post extra. (S.A.E.
. for full
details).
VOLTAGE STABILIZER
TRANSFORMERS
Will stabilize
MODEL
your mains
S
SILICON RECTIFIERS
..
.. 200mA 2/8 voltage. Ideal
..
650mA 7/6 for TV receiv-
200 P.I.V.
1.000 P.I.V.
800 P.I.V.
400 P.I.V.
400
..
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3
amp
5/6 ers and Indus7/6 trial
equip-
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MFD. 25.19.11.
& P. 2/6.
250 500
DC /
5/10/25/
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28.17.6.
Post
Paid. S.A.E. for
full details.
TE-5I
NEW
MULTI METER
20,0000 /VOLT
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'
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ment.
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December,
WIRELESS
PRACTICAL
674
12.65
CORRESPONDENCE SCHOOLS
I
PEEL CLOSE, DRAYTON BASSETT
Near TAMWORTH, STAFFORDSHIRE
Tamworth
2321
Post only
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 satisfactory. 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-
0
''Bend
up along
dotted lines
1Lead -in
hole
COMPONENTS
Eclipse +in. button magnets.
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.
3
3
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.
Fig.
4: Cover of the pick -up made from non -ferrous metal.
A
Thumbnail History of Radio -continued from
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 earphones from the power received from Continental
stations figured prominently. One firm of loudspeaker 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 righthand side! Another firm manufactured a wonderful 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
675
0
page
671
the days when the field of technical authorship had
a large element of ex-Army men calling themselves captain! An impressive title in those days.
Reflex circuits using valve and crystal combinations 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, published 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
December, 1%5
PRACTICAL WIRELESS
676
role
-"E611,404e
AN EFFICIENT
EARTH SYSTEM
i
BY ALAN FORD
1
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
However, connection from the
is so vast.
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 polythene 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
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.
much greater,
I b: The area of a metal tank is obviously
area
even if the tank was 6in. x 6in. x 6in. The surface
would be 216 sq.in.
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.
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 }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
1
I
2'-y+----
2'
T-} 7
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
p
Z
.I-
AO-
2'2
-1
1
1:2_,.L--
'D'
Four 6BA clearance holes for
attaching chassis to panels
4
1
.?;A
AO
!
2'z
O
"A" Sig dia
"B" To suit co -ax socket
"C
Sedia
Ap-I
i
I
.4".1;11
134;
y
Bend up along dotted
!
k_____4,.]
Bend -up
along
dotted
lines
lines/.
Fig. 5: Front panel (I.) rear panel
(r.i.
t
,
December, 1965
PRACTICAL WIRELESS
9sß
2
'
Bend up
I
T
-1--+i --
r
-
media
Holes Vtdia
'
±Ö'A
--A--O
'A' Holes
/e
for grommets
for B9A valveholders
6BA clear. for bolting
"C' Two holes
"D" Two holes 6BA clear. for bolting
L
I!
4"
c hassis
c hassis
to front panel
to rear panel
1'e
I
OA
o
T
Bend up
Fig. 6: Chassis
drilling dimensions.
by
to its compact nature, should not be attempted
the beginner.
The probe should be built into a metal can to
provide screening. A 35mm film container would
with
be ideal and should be lined internally move
do
insulating material so that if the contentsconnecting
no great damage is done. The cable be good the probe to the oscilloscope should
to
quality low -loss coaxial permanently attached
or quality
the probe, since cables of varying length the
strays
(hence internal capacitance) will alter
and thus affect the " picture of quality ".
Testing
When wiring up is completed the oscilloscope
can be checked for correct operation. After
several minutes warming -up time it should be
possible to resolve a fairly fine trace by adjusting
the
the brilliance and focus controls. Operating up
Y shift control should cause the trace to move if
or down just within the aperture limits, awhilst
slight
the trace is horizontally displaced
R32 or R33
adjustment to the value of either timebase
at its
should centralise it. Operating the
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
Note:Tags marked'MÇ are
earthing points to chassis
Fig. 7:
Wiring diagram of the timebase unit.
December, 1965
PRACTICAL WIRELESS
8: Wiring diagram
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
Fig.
of the
Y- amplifier
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.
unit.
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
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
679
from page 676
Wtndow
Aerial
feeder
Feed -through
terminals
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
Spark gap
Fig. 3: Discharge gap to
Earth
strip
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).
PRACTICAL WIRELESS
680
December, 1965
on the
Short Waves
MONTHLY NEWS FOR DX LISTENERS
All frequencies are
All times are in G.M.T.
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 regardless 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, 19302000, 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 19002200, 4,795 0530 -0900, 1600 -1855; 7,155
1300.
1030-
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; 10001300 (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 transmitters. 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,
Transmitter Building, Forest Side) sometimes uses 9,710 from 0230 -1830. Normally 4,850
is scheduled for use from 1300 -1830.
Nigeria: Nigerian Broadcasting Corporation (Broadcasting House, Lagos) will not QSL through bureaux.
English external service transmissions are at 15001600, 1700-1900, 2100-2200 on 7,275/9,690/11,900/
( Malherbes
15,255.
Somalia: Radio Mogadiscio, (Mogadiscio) has replaced 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 transmission 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.
-
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
cation ag
rang
qualitycommuniranges:
Mc/s-4.2
res) n
11.5
/0
1.5
u. éc/
scales
/me
band calibrated in frequencies plus an additional
scale in degrees. Two speed vernier tuning control with logging
slow tune action. Unique aerial Input stage exclusive reverse
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
Separate B.F.O. stage for
SSE) reception.7Callibrlineup.
te
nall
eenh
illuminated. Automatic
control. Panel phone jack for
ngVolume
'Matcvhing unit optional extra). Superb styling, metal cabinet
finish.
A.0a .Ó av Ready built.lustre
s
t a the fsFor
fantastic low
price of $19.10.0. Carr. 7/6. (Delivery December).
CODAR R.F. PRE -SELECTOR MODEL P.R.30, Considerably 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
Readybuilt complete
plugs and instructions. 4in.
Carr.
R.30X. Self
200-2á0v.
so provides
25mA at 200v. H. T. and 6.3v. 1 amp L.T. forAOther 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
411.15.0. Carr. 3/6. MODEL R.Q.10X. Self poweredinstructions.
for
200-250v. A.C. and also provides 25mA at 200v. H.T. version
and 6.3v. 1
amp. L.T. for other accessories
48.8.0. Carriage 3/6.
newest
compact AtraannsmitttBAND
foor
orr M
mobile useon
160.8Ometres. "The tiny TX with the fixed
BIG voice ". Size only
8t x 5 z 41a. (Base area is less than twothirds of this page!
High stability
to
type calibrated
Mc/s and
4 Mc/s
Airspat
PiPi-net
output, P.A. Plate current meter
plus
indicator. Plate Screen modulator. AM /CW switch and neon
Panel
key
Plug
jack.
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 RECEIVER. 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
eofls, factory aligned.
*Dlais calibrated In frequencies and-indegrees.
*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 ready
switchontandbring theWo be to your one
1w
cost. *Supplied complete with valve, one coil 25 -75at
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.
uo/e
I(rlr;
dé
/ Sablt
55
t
mos
d
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
December, 1965
PRACTICAL WIRELESS
682
EXPRESS ELECTRONICS
SURREY
:Jr
4:III
0110 xm
axu
"Zan 1III
32
Mullard
Telephone: Croydon 9186
FOR THE FOLLOWING BRAND NEW UNITS
AMPLIFIERS
LI5.I8.6
12 watt
TRIPLETONE HI -FI MAJOR
MAINTENANCE
MANUAL
the latest
Service Engineers will find
edition of the MULLARD MAINTENANCE 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:
5 watt
TRIPLETONE CONVERTIBLE
TRIPLETONE GEMINI STEREO 5 watt
3 watt
...
LINEAR
12 watt
...
LINEAR DIATONIC
30 watt
...
LINEAR CONCHORD
4 watt
...
...
ADASTRA 3 -3
14 watt
LEAK TLI2 ...
LEAK VARiSLOPE PRE -AMP
50 watt
...
...
LEAK TL50...
E6.19.6
E15.15.0
E6. 6.0
£ 12.12.0
15 watt
..
QUAD
...
QUAD STEREO /MONO PRE -AMP
LOUDSPEAKERS
...
...
6 watt
GOODMANS AXIETTE 8in.
...
...
10 watt
GOODMANS AXIOM IOin.
...
15 watt
GOODMANS AXIOM 201
BAKERS 'SELHURST' 3 or 15 ohm
...
8 watt foam
...
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JUNIOR 8in.
...
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15 watt
...
STALWART 12in....
...
watt
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25
12ín.
GUITAR
BASS
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STANDARD Heavy Duty 12m. 20 watt
...
25 watt
BASS Heavy Duty 12ín. ...
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watt
35
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AUDITORIUM ISin.
RECORD PLAYERS
£16.16.0
£4.19.6
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GARRARD SRPIO 4 -speed
£6.19.6
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£9.17.6
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Delivered free U.K. S.A.E. enquiries
.
MULLARD LIMITED,
MULLARD HOUSE,
TORRINGTON PLACE,
LONDON W.C.1.
HOME RADIO
SOUTH END, CROYDON,
(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)
expert in electronics. The only tools required are
as
the spanner and a pair of scissors. Build and rebuild the
often as you wish and check circuit at a glance through to
be
purchased
can
components
Extra
transparent panel.
expand sets as required. Adopted by Universities,
for
Technical Colleges, Schools and the Armed Forces
and the
electronics training."
p h one
made, including regenerative receivers f or ear
£5.18.6
KT46 Set No. I. Fourteen different circuits can be
operation.
£6.19.6
Reflex receivers.
KT48 Set No. 2. Twenty different circuits. T.R.F. and
including microphone and pick -up amplifiers and re eiver
KTSO Set No. 3. Twenty -two different circuits,
for loudspeaker operation.
KTS2
Set No. 4.
including
receiver.
a
Twenty-six different circuits,
6- transistor super- heterodyne
£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
catalogue contains five coupons, each worth one
shilling when used as directed.
Please
write your name and address in block capitals
NAME
ADDRESS
ROAD. MITCHAM
HOME RADIO LTD, Dept. PW, 187 LONDON
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 interesting 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
December, 1965
PRACTICAL WIRELESS
684
A SIMPLE
/,
30-BAND
PHONE
TRANSMITTER
II
I.
f
RATER
80IX
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
T
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 #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
The spacing of VC2 is not
spaced plates.
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.
1
Chassis Dimensions
Fig. I t Suitable power supply for the
transmitter.
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
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
WIRELESS
manner.
in Fig. 4.
685
A
suitable power pack-circuit is shown
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. immediately 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
H.T.fR
Aerial
RFC2
V1
eJ5
V2
C3
6L6
O01
yF
5
Transmit/
receive
switch
Carbon
mic
C9
O0O5yF
o
R3
470kL2
R4
toon
C4
50yF
RI
3.3
kn
C2
TSyF
Fig. 2: Simple two -band phone transmitter circuit.
www.americanradiohistory.com
PRACTICAL
686
December,
WIRELESS
1965
14
Crystal
in holder
gdla
3'4 long 20swg.
L2= 4Oturns 22swg.
1Y2dia 2q long
L1= 6turns
2
Chassis.
12"x
i4---1H
'x3
Fig.
3: Dimensions and positions of components.
required input, as shown by the meter, is obtained.
input
If 250V is avail..ble at the anode of V3 an
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. VC1 is
With 160m crystals it will be found that
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//
/
//
c7
ip69Pir:i'ilie,:iqml@I
/3/ /3
Red
Receiver aerial
terminal
meter
the required current by applying the test meter.
prods to chassis and negative on the 100mA
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 loudspeaker 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
// / /
holder
holder
ó RFC2
Fig. 4: Wiring and components under the chassis.
Jf
<
December, 1965
PRACTICAL
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
WIRELESS
687
give
t
Ir
UHF TEST OSCILLATOR
-f
full constructional details1
1,
\C
.,
*
3'
Ir
3
t
Ir,
DOES THE AERIAL
MATCH ?
t
Ir
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
*
*
*
*
*
.JI
SPOT WOBBLE
REPETITIVE FAULTS
JI
TV SERVICING
:.
YOUR PROBLEMS SOLVED
.Jl
These and many other interesting
articles appear in the November
issue of PRACTICAL TELEVISION
ON SALE NOW, price 2¡-
,.
COMPONENTS LIST
Capacitors:
CI
C2
C3
C4
CS
C6
C7
C8
C9
TCI
VCI
VC2
uí
25µF 25V
25µF 25V
0.011.1.F
mica
50µF 50V
2000pF mica
or ceramic
2000pF mica or ceramic
0.0I µF
200pF mica or ceramic
0.005µf mica
30pF beehive air -spaced
500pF variable (not miniature type)
2 -gang or 3-gang 500pF each section
Resistors:
f watt
180k01 watt
R3
470kO f watt
R4
1000 I watt
Miscellaneous:
RI
R2
3.3kí2
VI
6J5
V2
RS
R6
R7
10012 watt
20k0 I watt
330 I watt
6L6
I
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
Chassis 12 x
RFCI
RFC2
wafer
switch.
x Sin. deep.
2.5mH RFC.
2SmH 60mA RFC.
IOOmA
meter.
5
Three knobs. Terminals or socket strips, etc.
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.
A TRANSISTORISED
S.W. CON'V
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
be
should be simple to build and that it should test
easy to set up with the minimum of was
instruments. Over- riding these considerations to
the economic factor in that the converter had
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
in
that two crystals would be needed. However,can
the present design we are lucky in that we
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.
COMPONENTS LIST
Resistors:
470k12
RI
Capacitors:
CI
200pF
5000pF
330pF
C2
C3
VCI
VC2
Semiconductors:
Tr OC45
Tr2 0C44
I
Miscellaneous:
Xtal holder (to suit).
365pF variable
100pF variable
LI.
L2,-1
L3, L4, -See coil table
L5, L6 ,
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
overlap
these two bands, so that there is no scale may
be
and a smooth calibration over the scale
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
the
controlled. the crystal being placed between The
base and collector of the transistor.
L3
collector current of the 0C45 is drawn throughThe
which is tuned to the crystal frequency by Cl.
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
by
purpose of an r.f. amplifier and mixer, and,
current
virtue of the fact that it draws emitter section.
through L4, it is coupled to the oscillator tuned
The aerial is coupled by L2 to LI which is Ll is
by VC2, the tuning capacitor. The tap on
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 capacitance for the lower frequency band. The incomthis
bined r.f. and local oscillator signals are winding
way amplified and appear across L5. this
being tuned by VC1 which is a " peaking" capacitor. L6 is used to couple the converter to the main
set.
Construction
The construction of the circuit is fairly convenhe '
tional and the circuit would appear to
reasonably tolerant as to layout since experience
'
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 proposed 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
3.
template for the circuit board is shown in Fig.has
As can be seen from the layout, no attempt
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, 2.5if the
2.65Mc/s will prove satisfactory. Of course, on
the
constructor is prepared to allow an overlap
receiver scale then crystals of frequencies other
than these may be used -provided that theof final
the
output is within the frequency coverage
main set.
The coil winding details are given as Fig. 4.
VC1
L6
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.
H.T.-9V
The core of L3 is then adjusted
for maximum response from the
converter and VC1 rotated until
Output
the point of maximum response is
found. It should now be possible
to tune over the whole band
Crystal
peaking where necessary with VC1.
The gain over the whole coverage
should be even with no sharp
peaks or drops which cannot be
Jsnnnr
levelled out by adjusting VCI. If
R1
bO
this is not so, or if the whole of
470k11
Tri
the band cannot be covered, then
OC45
L
the core of L2 should be re -set and
the operation repeated. When a
C1
200pF
satisfactory arrangement has been
found the converter should be
to the second band and
switched
C2
repeated.
operation
the
T000pF
It may well be that the
the
of
settings
optimum
722
page
-continued on
circuit.
-
Fig. 2: The theoretical
www.americanradiohistory.com
690
PRACTICAL WIRELESS
December, 1965
CIRCUIT DISGUISES
BY R. LEYLAND
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 waveforms, 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.
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 maintain 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
.
691
PRACTICAL WIRELESS
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
bypass
a
without
resistor
capacitor in the cathode lead or
(a) Groùnded
lead of a
in the emitter
of
is
it
where
transistor,
considerable assistance in controlling 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 transistor, 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
emitter
(b) Grounded collector
Fig. 2: Phase shift oscillators.
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
(a) Basic circuit
3: Compound emitter followers.
Fig.
Tl
(b)
pop-
+ve
pnP
www.americanradiohistory.com
(c)
Pop- nPn
692
NEWS AND.
The Meaning of Amateur
RECENT visits
to Amateur
(Ham) radio stations have produced 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 WIRELESS has produced quite a few
designs of its awn.
ZENITH AM /FM RECEIVER
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, precision Vernier tuning and
A. Heathfield,
Harpenden,
Hertfordshire.
Good Old
I
HAVE
Octals
read in
over the
PRACTICAL
past few
months, various people's views
on the use of octal -based valves
as opposed to B7G and B9A
WIRELESS
based types.
I am surprised that none of
your correspondents has mentioned 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, collectively, 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 dissenter, unanimous in support of
the idea.
Accordingly, I am now arranging for a series of articles to be
prepared by specialist contributors, all with considerable professional experience behind them,
and it is hoped to make an early
announcement on this special
series in the next issue. -- Editor]
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.
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 throughout 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 diameters 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
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 p.m., with the calls averaging
about 18 an hour.
By
I
www.americanradiohistory.com
693
..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 modulation techpique used on
each transmitter. This technique, 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
major export order, worth approximately £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 computer, installed in one of the Qantas
A
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 remaining 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.
www.americanradiohistory.com
Correspondents Wanted
I WOULD like to hear from
P.W. readers in Great Britain or
in any other country who are
of
" Gramdeck "
owners
recording equipment. I am 18
years old.
Henry Raymond.
Duchess of Kent Hospital,
Sandakan,
Sabah,
Malaysia.
I Am interested in communicating with radio fans the world
over, especially the United Kingdom. I am a Detective Constable
and interested in radio experimenting.
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. am 16 years old and
very interested in transistor
circuits and SWL.
David Hendon.
1
Copthorne,
Wix Hill. West Horsley,
Surrey.
T AM interested in short wave
listening and electronics in
general. I would like to correspond 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.
will promptly answer any
I
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 construction 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.
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 converting 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 converted, 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 respect 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
Fig.
\
\ \\o\\\\
\\\\\\\\\\\\\\\\
3
\\\
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 manufacturer, 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 recording 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 connections to the old heads are removed, after taking
careful note of where the wires lead. The new circuitry 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 programme 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 convenient 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 "crosstalk " 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
695
WIRELESS
PRACTICAL
December, 1965
NULLARD "3-3" á
HI -FI AMPLIFIERS
262gn TAPE RECORDER
for ONLY £19.10.
3
care 12/6
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 forward and rew'nd. take 7' reels,
mike and gram input. Straight
through amplifier facilities. Output sockets for ext. speaker.
monitor or external amplifier
Super -imposed switching magic
eye recording level and maim neon indi
404
cater. Volume and tone controls 7° x 4'
Attractively styled cabinet
speaker.
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-
OFFER!
PROFESSIONAL GRADE
DOUBLE -SIDED
SPECIAL OFFER 8' Message
tape 150', 8 /9; 3' L,P, 226'.
4/8; 3' D.P. 300', 6 /6. P. A
teach side coated) 51" reels only
Special price offerw g7,2o, -
P. per reel fid.
post free
7/6; 12'
x 8 ", 8/ -,
Alumin. Sheet,
6' x 9'. 1/8; 6'
416. etc.
etc.
18g.
x 12 ",
6' z 6', 1/ -;
2/ -; 12' x
12',
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.
Ditto, but less power unit, 69.19.8,
L10.19.6
Circuit and construction details, 4/8. free with kit.
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,
575pF,
100pF- 500pF, 11d.
9d.
Resistors -Full
5,000pF. 1 /6.
Range 10 ohms-10 meg, ohms 70%
M.
(Midget
1W.
t and 4W, 3d.,
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
carriage
7 /6.
UNITS.
Designer- approved kit of parte.
4
valves, 20/ -.
FMT1, 5 gus.
FMT2, £7.10.0. 5 valves, 86! -. JTV
MERCURY 10 goo. 3 valves. 2216
4 valves, 28/8.
JTV2 £13.19.8.
NEW JASON FM HANDBOOK, 2/8.
48 hr. Augiment Service 7/8.
JASON
['.
&
FM
TUNER
P. 2 /6.
eram e (Compression
TRIMS ' ' ;.
Type ) -30pF, 50pF, 70p0', 9s..; 100pF/
150pF. 1/8; 250pF, 1/8; 6000F, 1 /9.
PHILLIPS. Bee Hive Type (cons airspaced)- 2-8pF, 1 / -; 3-30pF, 11 -.
KNOBS- Modern Continental types
Brown or Ivory with Gold Centre;
dia.. 9d. each: is /,', 1/- each;
Cone. knobs ivory with Gold Centre
1/' dia. 2/9 per pair. Matching ditto
2/6 ea
l'
LARGE SELECTION AVAILABLE.
METAL RECTIFIERS, 8TC TypesIt 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
51-A
10W 8
BOLLARD "5-19 AMPLIFIER. 5 valves
with
and 15 ohms output. Mullard'a famous circuit
trandormer
output
quality
linear
ultraduty
heavy
and Ind 7/6.
Basic amplifier kit price
Ready built 114 gas.
£9.19.6
fir.
&position
PANEL KIT. Bass. Treble and Vow controls
tape
switch for
Ditto, retry wired.
KIT,
811.19.6.
PANEL
CONTROL
AND
T
AMPLIFIER
£19.19,6.
Based on Mollard's famous 9 -valve (*KEYING
2 -VALVE PRE -AMP. IINIT.
treble and 5- position selector
circuit with full equalisation. with volume, base,Carriage
3/8.
switch. Size 9 z B z 2;In. Ready Rollt 27.19.6,
CONTROL
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/.
8/Midget Driver Trans. 9:1
Midget Output Trans. Push-
DE -LUXE
RECORD
PLAYER
KIT
II-
Pull-3
ohms
mFd.-500
amid
ee-LMISd,
2 / -, 12V,
160
Condensers
mPM.
werldeg:
v.
.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
Incorporating
Sp. Garr. rd
4
6 VALVE AM -FM TUNER UNIT
2
distortion. Bronze escutcheon panel.
11
Jack Plugs. Standard 21' Igranic
Screened Ditto, 8/8.
Type, 2/8,
Miniature scr. 14', 2/8. Sub -min. 1 /3.
Soldering Irons. Maim 200/220V or
230/250V. Solon 25W Inst., 29/6.
Bits. 1/3.
Spare Elements, 5/8.
65W, 29/6. etc.
-3" Amp.
Complete Kit only 26.19.6. Carr.
Wired and tested 88.10.0.
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.
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.
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',
6,.,,,,'"/
ohm output
15
valve, 3 watt 51.6
quality at reasonable cost. Baas Boost
and treble controls quality sectional
output transformer, 40 c /8-26 55 /5
+ 1 dB, 100mV for 3W. leas than 1%
3
Bargain of the Year Offer
-Cancelled Export Contract
ohm &
"5.10"
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.
with
off -white
charcoal -;Crey and
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,
COMPLETE KIT
1
Carr. and ins. 12/8 Ready
3.19.6
wired 30 /-
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
Control
VoL
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
Ost
Ear Plug Phones-La.
tmenta) type aft lead, la* plug
and socket. High Imp- Si, Low
imp., 7/8.
extra.
perspex control panel
ID ®lusted
escutcheon, 7/8 extra. Four contem- Phono Plugs, 9d Phono Sockets (open)
Ditte (closed). 1/ -, Twin Phono
d,
legs
ói0, 10/6; UM.
mounting
porary
Sockets open/. 1 /8.
1116; 12in. 12/13 xtr,
7 VALVE AM /FM RADIOGRAM CHASSIS
Valve line -110 ECC85, ECH131, EF89,
EABCBO, 2184, EM81, EZ80.
Three Waveband and Switched Beam
Long
positions.
HF FM 88 96 Mc
0-- 2,,000
c
New 1965 Model now available
mV
Phillips Continental Tuning Insert with
permeability tuning on FM and com400
bined AM /FM IF transformers.
Re/e. and 10.7 Mc /e. Dust core tuning
Latest circuitry including
all rods.
watt
Three
AVC and Neg. Feedback.
output. Sensitivity and reproduction
of
very high standard. Chassis size
13;x
a etin. Height 7410, Edge illuminated 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:
THO 2188. Terns C.W.O. or O.O.D. Post alud Pontiac
8 / -; b lb. 3/9; 5 lb. 4/6.
www.americanradiohistory.com
9
a.m. -6 p.m.
fa
4 Its.
l/. 1
1
p.m.. Wed'
1/S; 3 D.
696
PRACTICAL
WIRELESS
December, 1965
ADAMIN THERMAL
STRIPPERS
The
new
ADAMIN
thermal wire strippers
allow one-handed operation, using a simple tweezer action.
They strip coverings of
up to about 5/32 inch diameter with absolutely no
risk of damaging the
conductors.
FOR
FOR
PTFE
PVC
use Model 2B24, (illustrated), available
24 volts only.
and similar low temperature materials,
use Model 236, available for 12 or 24
INSULATION
for
INSULATION
volts.
LITESOLD TRANSFORMERS permit
operation from any mains power point.
Free details of the whole wide range of ADAMIN and LITESOLD soldering equipment
In brochure SP 10.
safe
LIGHT SOLDERING DEVELOPMENTS LTD., 28 Sydenham
Surrey.
Telephone:
CRO
Road, Croydon,
8589
KITS WITH A FUTURE
STEREO
AMPLIFIER ASSEMBLY
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
Build for
F.M. TUNER
stage Input Selector
E2.7.6
-amp. and vol. control EI.17.6
Pre -amp. with tone controls 03.2.6
Send for leaflet describing entire range
S
Pr5 e
mRRTin
watt amp. (3 ohms) E5.12.6
watt amp. (15 ohms) (6.12.6
Mains power supply
02.15.0
10
10
3
or
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
MARTIN ELECTRONICS LTD.
Martin Audiokits and Recordakits
are obtainable from good stockists
everywhere. In coses of difficulty
please write direct.
for quality
IS ohm system
Full details
NAME
-- -
1S4 -155 High Street
Brentford Middlesex
of Martin Audiokits please
----
-
I
I
-_
ADDRESS
MARTIN ELECTRONICS LTD., 154/155 HIGH ST., BRENTFORD, M'SEX
Phone: 1SLeworth 1161 ; 2
(Block letters)
www.americanradiohistory.com
-
Pw12
I
697
PRACTICAL WIRELESS
December, 1965
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 mounting 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 optimum 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 discrepancy 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 conditions. 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.
The
Operation is fairly straightforward.
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
2: The Pre -amplifier
circuit used by the author to
Fig.
obtain extra gain from low
input signals.
--f
Slide
switch
j_tesclaL
Erase
Replay
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 potentiometer 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
or
is not therefore such an expensive, difficult
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
The
impedance and raise the input impedance. either
arrangement of Fig. 3b is applicable with
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
by H. W. Hellyer
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
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 timeconstant of the combination: thus for a speed of
7 #in. /sea the original standard was 100psec with
-at
a turnover frequency of 1.6kc /s. With improvements 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 amplifiers 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
When again
humidity tape becomes brittle.
subjected to normal humidity the tape will tend to
www.americanradiohistory.com
Sheet
Paxol i n
sistor projector
Special offer
12 panels 6 x 81n. 5/ -.
Bargain of the Year
complete kit
of parts to build
A
wave
superhet
receiver
at only
`-T
AIRCRAFT
RADIO
3916.
Post
and
Ins. 316.
"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
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 transformerrectifier, smoothing and load resistor, 5000
and 500 mid condensers. zener diode and
Instructions. Real snip at only 14/8 plus
Designed to
¡/
Famous wart me
1NFIIA-RE0
cat's eye rued
Brings sunshine into your
S(NSITIVC LA
home. 150 watts of light for seeing in the
but soez only 40 watts.. dark. This is an
FLUOIIESCENT
Beautiful fittings with infra -red image
6COEEY
cell
glass, not plastic centre, converter
fluorescent tube and with a silver caeschoke control. Made by ium screen which
MENINE WINDOIM
Philips. Will give a lights up (like a
cathode ray tube)
lifetime of service.
electrons
when
Regular price 24.15.0.
released by the infra -red strike it. It follows
Cç
that as light from an ordinary lamp is rich
65
plue 8/6 carriage and insurance.
Special Bargain pries
in infra-red these cells will work burglar
yellow
black,
blue,
red,
Please state colour of glass centre white, pink,
mounting alarms, counting circuits, smoke detectors
or cream. Also whether plug into lamp holder or ceiling.
and the hundred and one other devisee es
model 80 watt model 99/6.
will the simpler type of photo cell. Here
golden opportunity for some
then is
interesting experiments. price 6/- each. Post
3 /.. Data will be supplied with cells if requested.
/
transistor/
2
SNIPERSCOPE
CIRCLE -LITE
Ideal for tran-
6
699
WIRELESS
PRACTICAL
December, 1965
RECEIVER
Speaker Bargain
Type CW 0480 48 D
This is part of the equip-
121a
speaker.
Highflnx
magnet type
with either
S ohm or 15
ohm speech
Will
coil.
handle up to 10
watts Rand new by fsmoas
maker. Price 29/6 + 3/6 post and insomnia.
SPOT OR FOG
LAMP
THIS MONTH'S SN
operate
eine"'"-e%
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 transformer 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
Capacity bridge, electronic
Voltmeter,
megometer, etc., etc., at 27/6 plus 7/6 post,
which is less than the price of the transformer alone.
Orsm or Tape Motor. Made by Garrard for
their best Changers, each one "LAB" balanced. 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
Made by
Tape Recorder
fixing bolt. Remarkable
bargain. Price 12/6 4- P. a P. 318.
and
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
This Months' new Bargains
a
pencil
Luce, Flat
beam. 36 watt Suitable for car.
boat, caravan. etc. Complete
with 6 or 12v bulb, flex, cables
CAPSTAN DRIVER
8/- post.
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
High -
fidelity loud-
ment RU19, American
made equipment for the
Navy. It o a 5 -valve
receiver with a really
beautiful precision tuning mechanism. Brand
new and In original
packing but less coil
units. Limited quantity
only. 19/8 pius 3/6 P. er P.
SELF
ENERGISED
TELEPHONES
require no 'eel,.
terieo: In fact they
have only to be conpair of
nected by
wires. They can thus
These
completely portable,
battery operated instrument at
to
a remarkably low price. So low in tact that you can easily afford
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
and 741 cast rewind time --IV spool gives one
track -twin speed
hour playing with standard tape weight 7 lbs. Size 8 x 11 a 55.
Complete with batteries, microphone-tape spool and instruction
good tape and keep
manual. Nothing to go wrong if you use
heads clean. Demonstration gladly given at One Croydon shop.
special Snip Price This Month. £11.11.0. Post & Insurance 601.
Driven,
7
and
coots
each.
THERMOSTATS
Type 'A' 16 amp for coaecollinv room hostess,
greenhouse. airing cupboard. Has spindle One
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.
INFRA RED
circuits. Rennie
good
extremely
maintenance
nothing.
are
I
15/Handset. only
poet eta 3/6. Two, post free.
bell
are
Iii
TWO -WAVE BAND
pointer knob quickly adjustable from W80°F. 9/6 plus 1/- post. Suitable box for well
mounting. 6/ -. P. a P.
Type
'B'
1
/-.
17ta. long rod
15 amp. This Is
type made by the famous Bonnie
Co. Spindle adjusts We from 90550°F. Internal screw alters the
HEATER
Make up one of these latest
type heaters, ideal for bathroom, kitchen, bedroom. etcWall Mounting Thermostat.' By Satchwell They are simple to make from
intended for use to control tubular or any our easy to follow instructions -nee Mlles enclosed elements designed
type of space heaters indoors or in a green. for the correct infra -red wavelength (3 microns). Price for 750 watt
house- Adjustable over 40 /80 deg. Complete element and metal casing as illustrated, 19/6 plus 2/6 post and hunrwith mounting screws 29/8. plus post 2/9 ance. Pull switch 3/- extra.
(normal price re at least twice this).
Morganite Sealed Pots, Another batch of
Garrard Auto Record
these has arrived and we can now offer quite
Player Model A.T.5
a range namely: 5K, 50K, 100K. 250K,
This le undoubtedly the
{ meg, 1 meg, 2 meg, all at 6/- per dozen per
finest Auto changer made
value, plus 2/9 poet on first dozen, then 1/in f cat its large heavy.
per dozen. Less than one dozen price is 94
nonagnetic. die cast
each, even this is only about one -tenth of the
Wroteb,e and biaa comcatalogue price and this is undoubtedly one
pensated constant pressure
of the bent pots available.
tybne together with its
Tuning Condensers. 2 gang .0005 mFd air
laboratory series motor with
spaced standard size with good length
balanced rotor make It almost
Other
spindle 30/- doz. or 3/9 each, post 2/9 up to
a transcription unit.
sin, 3/0 per dozen.
special A.T.5 features arc:- Will take 8 records which may be
be stopped whilst
-may
adjustable
presume
stylus
mixed
sizesmFd
type
.0005
Bakelite
Toning Condenser.
playing a record without rejecting rune record-fitted with latest
inch eplindle 25 /for tuning or reaction,
pick -rap for playing stereo or mono record,.
per doz. or 3/- each, post 2/9 per doz.
OFFER ED AT THE AMAZING PRICE OF 18.15.0 plus 6/6
OZONE
OUTFIT -for removing smells
Carriage and insurance.
and generally hnproving any oppressive.
Kit consists of Philips
at mosphcre.
Ozone Lamp and mains unit, only needs
box. 19/8 plus 3/6 postage and insurance.
use. 7/8 plus 2/6 post.
AUTOCHANGER BARGAIN
setting so Mk could be a:Wettable
over 30° to 1,000 °F. Suitable for
furnace, oven kiln.
controlling
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
17 Waterproof
Where postage is not definitely stated man
extra then orders over 83 are poet free.
Below 68 add 2/9.
fitted into existing
be
Heater Wir
;de. length 70 watts, self regeelatlag
temperature control. 10/ -, post free.
(CROYDON) LTD
ELECTRONICS
P.W.
LONDON ROAD WEST CROYDON, SURREY
Dept.
Post orders
266
to:
4
Springfield Road, Eastbourne, Sussex
www.americanradiohistory.com
700
PRACTICAL WIRELESS
R.S.T.
211a
0A2
003
111.5
11.05
114501
1115
sea
3Q4
3Q:,
384
3V4
6/. 604
4/9 671
e/- 675G
8/. 6760
4/- 678/2
6V40
8/- 6711
5Y30T 4/6 6713
52407 8/. 6714
6.6.7
6A8G
6.407
SAMS
6A1S
OARS
BANG
6.40
6
6AT6
6AÚ0
6280
15 /-
8/6
8/5/- 606 0
6080
6CD60
2/6 60116
3/8 6CW4
6/6 8D6
818 676
07411
5U4G
6/301.2
10/6
7/6
7/9 61187
8/- 6BW6
7/6 6BW7
e/
165
1T4
18/- 61,23
15/. 606
8/6 6118
3/- 635M
4/6 6350
6/- 6350T
2/8 6.16
2/9 637M
637/2
8/6
1/9
3/9
6/-
22/6
8/-
14/2/9
6/9
9/5/-
4/-
416
12/6
5/-
12/6
9/6
2/8
1/3
4/8
Rqé 6370T 7/a/6 616/2T 5/8/- 6ß7M 6/-
4419
/9--
61170
61.1
61.60
6L18
6Q70
6Q7GT
6817
6807
6807
101.011 10/-
3001
12ÁH8 10/6
12AT6 4/6
9/- 124.17 8/8
7/. 12AUn 5/9
6/6 12.61.17 5/4/. 1:1%7 4/6
%IFS
9/6
7/7/8
2/6
68J7
5/68E70T 4/9
681.701 4/9
687701 4/ß8Q7
6/681£7
1/3
10713
12/8 30017
6/6
6%4
1213.46
121E6
4/9
12ßH7 5/9
120801' 7/6
1.271
10/6
12J50T 2/8
6150
8,6 11807
4/9
787
7Y4
9BW6
1001
1001
1071
1073
1079
10718
ß0L1
18/6
5/.
8/-
9/18/-
19/6
12//-
9/9
9/10/-
128117
11837
1.28 %7
128117
1487
19AQ5
2001
6/8
ATP4
12/- ATP5
9/- AT??
30FL1 10 /6 AU2
301,15
30117
12/. AUS
12/6 2,21
3071.13 12/8 01.33 12/6
3071.14 12/6 CY31
10/35.45
17/- DAC32 7/6
35I.6
5/9 DAF91 3/3
32W4
4/0 DAF96 6/3613
10 /- DC090
7/-
35240T 3/9 DP3:3
3625
5/6 D770
37
42
5/. D791
4/6
5/8 6085
6/6
2/9 3005
6/8
3/9 ß00D6024/9
2/9 501.601' 6/-
6/.
20/- 76
4/6
7/8
DP92
DF96
D1177
DE31
DE81
DE91
DE98
DUO
DLbI
SPECIAL 24 HOUR SERVICE
7B041
EBF89
811L1
2/8
8/8
5/9
17/6
EB1.1110/5
7Cti'40
-/.
E0081
3/3
E0084
5/6
ßtx.v? 5/70063 4/6
80085
5/- E0088
6/- 70980
5/9
8/9
8/6
6/E0221 19/.
6/- E01133 13/8/6 ßCII4'1 BF
EC782
7/9 E01181.
5/5
5/- ECH83 6/6
7/9 E0190
ECL82
EC1.83
8/6
7/4/9
3/6
6/6/6
8/-
10/- 88113
65/20H2
11/- 65A2
8/6 DL93
ß0L1
12/6 19052 11/6 01.04
2074
14/- 16004 1216 01.95
ß0P5
12 /. 801
5/- D198
26.48
6/6 897
D270
6/.
251.60T 4/6 866
10j 01711 7/2ßY5
8/- 964
4/- DY87
7/9
2624
6/3 1625
5/- 78800 14/2535
7/- 4022.411 6/- 7.650
2/2528
8/6 6763
102 EABC40 5/6
28137
6/- 7193
1/8 7.1E49 7/6
30016
9/6 7475
2/6 71341
4/6
OBSOLETE TYPES A SPECIALITY
QUOTATIONS FOR ANY VALVE NOT LISTED
Postage 6d. per Valve.
C.W.O. No C.O.D.
EB91
EBC33
Special 24 Hour
Express Mail
Order Service
Eel.86
6/6/6
9/.
E79
8/6
90/-
E5'39
9/6
5/6/6
E736
EF37A
E741
E760
7780
7E85
2786
EF89
7791
7792
3/2/-
4/5
4/6
6/6
4/2/9
2/6
-Sat.
9
-5.45 p.m.
a.m.
Wednesday p.m.
Open Daily to Callers
Tel. MPTcham 6202
I
3/- E798 10/- 178
6/- F.FI83 6/8 N108
4/6 7E184 6/6 NOTI
M- ESC20 3/6 E131 3/- NGT7
6/- 7E780 5/- 71.33 17/6 0'L4
9/5 EEF83 7/3 EL34
9/6 PC86
119
7/4/6
3071! 10/- AZ31
7/9
30719 14/- 013L1 12/6
8/- 30PL1 11/- CE50'1 5/-
8U4GT 10/- 1227GT 7/3
6030
7/6 12ß70T 8/616M
8/- 12E8GT 8/3
6160 3/6 12Q70T 8/6V6GT 7/- 12877
6/6
6%507 7/6
7B6
11/7117
7/8/6 705
10 /2/6 706
8/4/3 706
8/3/- 7117
5/.
8/6 777
12/-
6ß70T 4/6
68115
62861 8/6
6E80
8/.
esie6 éié 81í80T 8/3
624121 7/8 61125 20 /6Be6
Mon
VALVE MAIL ORDER CO.
STREATHAM ROAD, MITCHAM, SURREY
5/8 61117
5/- 65E8
1A7
11)5
December, 1965
15/16/- PY8800
8/- PY801
25/- R9
4/. 719
10/- R05/500
UC1,69 3/9
5/9 0E41
7/6/3 UF89
6/4/- 01.41
6/9
7/- LTL84
5/4
06180
7/E141
7/8 PC89
0/5
59/- UU6 18/6
71A2
7/6 PC97
7/- 8130
10/- 171.77 10/8
71.84
4/6 7(,`C84 5/4
11879
5/ß190
61- PCC89 9/8 8741
1/6 L'Y21
7/4
EL95
8/- 700189 10/- 8761
1/- UY41
4/6
711:34
9/- PCF'90 6/6 8U'15 1B/6 L`Y8,6
4/0
EM80
e/- PCF8" 6/- 817l15012/5 101197 27/0
7281
-/- P(:F84 8/.
VCR517B
E294
é/. 70786 8/6 TDD4 7%30/781715027/8 PCF901 9/9 TH41 20/- VCR617C
14Y51
P0F80^ 9/9 U10
7/80/7186 6/3 PCF805 10/6 U14
V2P4G 17/72E36
4/9 P07806 12/- 019
30%. VR105/306/E240
6/6 PCB808124 6726
10/. V11150/306/EEO
6/- 7C1.81 6/6 1.726
10/. VT73 12/6
EZ80
5/6 P0193 8/- U78
3/6 VT31 90/7281
3/6 PC1A4 7/. 17191
11/. 17.7111 6/.
G230
9/6 PCLSS 7/4 17261 11/6 P17120 1010239
9/- 701.86 8/9 0301
15/. V17508 26/.
GZ34
9/9 PE1A4 20/. 87403
6/6 W812 517138 28/6 72724 80/. 17801 15/6 %78
28/6
KT61 17/6 PRN45 8/- 0.4134780 5/8 170
89/ET66 12/- FPN46 2/9 U4742 7/. 181-5 9/.
ET81 10/- PL36
9/6 URC41 6/6 %P1-5 5/ET88 m/- PL81
7/. URG11 7/.
ETW61 4/3 71.82
5/- 87B780 5/9 T5É
6
ET241 8/. PL83
6/- 1711789 6/8 3801 4á//2L4 17/6 PL94 6/8 17CC84 8/6 31,77 18/6
161.8
12/6 PL600 14/6 170785 6/6 5(:71
2574 12/8 P%4 18/6 UC788 8/8 CV1596 80/40/.
2014 4/- 7Y38
8/6 87CH42 7/- .4Ca10
2140 12/8 PY81 3/6 1701181 6/8
94.e-0
1137
10/- PY8'2
5/6 UCL89 7/9
117
SETS OF VALVES
DA791, D169I, nx91, DÚ92.01.94 ..
.. Set of 4, 19/DAF96, DF96, D1(96. DL96
Set of 4. 25/BRAND NEW TRANSISTORS
0035
9/6
0072
6/00011)
4/0044
4/8
0081
OC82
4/5/0045
3/8
0081m /Dr 18/9
00890
6/0071
4/8
FULL-TIME COLLEGE COURSE
THE
PEMBRIDGE
COLLEGE
OF ELECTRONICS
PROVIDES TRAINING
IN RADIO
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 receivers 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
Full-time Course in Radio and Television.
Name
AND TELEVISION
Address
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Doe
'701
PRACTICAL WIRELESS
December, 1965
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.
control provision.
Slide projectors can be operated by solenoid and
relay actuated by pulses recorded on tape, or metal
foil strips.
STRAIGHT-THROUGH AMPLIFIER
TAPE
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 superseded by multiplay techniques. In conjunction
with fade erase and variable bias it can be effective 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
TAKE -UP SPOOL
The spool on to which the tape is wound after
passing the head system.
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 0.40.5 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 developments have led to one company marketing a quadruple 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 manufacture. Polyester tape is tough and does not stretch.
It has good temperature and humidity characteristics. 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)
Tape length (feet, in.)
Reel
Size
(ins.)
Std.
LP.
DP.
TP.
3
ISO
175
250
250
450
600
900
1200
1800
2400
300
400
600
900
1200
1800
2400
3600
450
600
900
31
4
300
4;
--
5
5;
600
850
7
8+
1200
1800
I
1200
1800
2400
3600
-
Playing time
at 31 in. /sec.
Std.
LP.
8m.
9.20
13.20
13.20
16m.
24m.
32m.
32m.
45.20
64m.
96m.
48m.
64m.
96m.
-
www.americanradiohistory.com
120.8
(Mins, secs.)
(Single- track)
DP.
TP.
16m.
24m.
32m.
48m.
64m.
96m.
120.8
21.20
32m.
48m.
64m.
96m.
I
120.8
180.12
-
180.12
702
December, 1965
PRACTICAL WIRELESS
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 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.)
TAPE GUIDE
TELEPHONE PICKUP
Flanged or grooved pillars or pins of nonmagnetic material, positioned to guide the tape
into its correct path past the heads.
Induction coil system used near telephone
receiver to pick up and record telephoned
messages.
TAPE POSITION INDICATOR
TEST TAPE
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 consisted 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 tightness of respooling, which can vary greatly.
TAPE PRE -AMPLIFIER
Special type of pre -amplifier, incorporating
equalisation circuits, and, if used also for recording, 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.
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 indicated 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.
TAPE SPEED
(To be continued)
See " Speed ".
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 month27th.
www.americanradiohistory.com
PRACTICAL
December, 1965
703
WIRELESS
LEARN
ELECTRONICS
-AS
YOU
BUILD
CIRCUITS
EXPERIMENTS
TEST GEAR
over
including
.
.
.
CATHODE RAY OSCILLOSCOPE
e
Valve Experiments
Transistor Experiments
Electro- magnetic Experiments
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
Basic Amplifier
Basic Oscillator
Basic Rectifier
Signal Tracer
Simple Counter
Time Delay Circuits
transistors, photo -tube, modern type chassis board; printed circuit board; full range
all hardware, wiring and every detail
resistors, capacitors and inductors; transformers; potentiometers; switches; transistors; valves;
of all experiments carried out. All practical
required for all practical work plus CATHODE RAT OSCILLOSCOPE for demonstrating results
needed.
if
and
advice
Tutor
service
MANUALS.
work fully described in comprehensive PRACTICAL
The full equipment supplied comprises: valves,
carrying out
This complete practical course will teach you all the basic principles of electronics by
all
experiments and building operational apparatus. You will learn how to recognise and handle
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
fields of
ACTUALLY WORK BY USING THE OSCILLOSCOPE PROVIDED. An application is given in all the main
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
SENT IN ATTRACTIVE BOX
COMPLETE
completely NEW up -to-date
experimental
study
home
A
course by
BRITISH NATIONAL
RADIO SCHOOL
Britain's Leading Electronic
-
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REASONABLE FEE -NO EXTRAS REQUIRED
MATHS USED OR NEEDED
NO PREVIOUS KNOWLEDGE NEEDED
O
ADVICE SERVICE
r
POST NOW
BRITISH NATIONAL
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PW 12.65. !
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PRACTICAL
WIRELESS
December, 1965
RETURN -OF -POST
An
integrated
hi-fi turntable
unit from only 11 gns ?
ON CASH OR C.O.D. ORDERS
GARRARD GRAMOPHONE EQUIPMENT
Credit Terwu
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Total
Payments Credit
Model 50 (G0ß Mono PU)
59.19.6
51.19.6 12 of 15/5 511. 4.6
Model 1000 (GCS Mono PU)
28. 9.6
51.18.6 12 of 13/5 59.14.8
Model 3000 (9TAHC Stereo/
Mono PU)
512.15.0
52.12.0 12 of 19/- 214. 0,0
AT80 (GC8 Mono PU)
212.19.6
22.12,6
12 of 19/5
5.8
A70 Deram PU) ..
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228.11,8
LAB80 (Denim PU)
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SP25 (OCR Mono PU)
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MULLARD AMPLIFIER KITS
ha.e full stocks of all components for the Nullard 510. 3-3, Two and
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Seven Watt and Three Valve Stereo Amplifiers all as described
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Nullard OA81 Diodes, 1/6 each.
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Small tag stripe. Assorted packet 2/e. Postage extra on W the above
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MARTIN AUDIO KITS
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 cartridges. 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.
+
+
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£1.12.4 P.T. £11.11.0
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£2. 1.2 P.T. £14.14.0
Goldring Manufacturing Co. (GB) Ltd.,
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Telephone: Leytonstone 8343
MARTIN FM TUNER KIT
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Complete transistorised Hl -Fi Pre -Amplifier and Nain Amplifier comprising Unit 1, (Five -way input selector). Unit 4 (Pre -Amp. with volume,
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LTD
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WEYBRIDGE, SURREY
Telephone: Weybridge 47556
Plano nata; Postal bonnets only tram this nddra-
www.americanradiohistory.com
PRACTICAL
December, 1965
705
WIRELESS
No.16
What's
With Tape?
REMEMBER
word those
association games we once
played? When someone snapped
" Pen " and we answered " Ink ",
" Tree ", "Chair "
" Wood "
" Uncle
" Sit ", " Bottle "
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.
consortium of famous
A
manufacturers. Blue Spot, Grunhave
Telefunken,
dig
and
cassette -loading
a
developed
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" principle -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 beautiful 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
standards
international
to add to the shelf of boxed
tapes that we are always intending to tidy up. And, of course,
to keep up with the Ioneses a
second tape recorder, cassette
version, which was already obligatory, 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 commented : "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".
www.americanradiohistory.com
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 collection 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 walletsvideo 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
I
dollars-less than £350).
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
And
here".
have not mentioned
I
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!
.
.
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
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
250V
Mains
b anstormer
Tri
Mains
h
transformer
500V
R1
01
D1
VR1
225V
200V
AC.
250V
Heat
sink
250V
-6V
D1
0A81
Paxolin
Fig.
1
(above): Method of mounting componenrs.
Fig. 2 (right): Inverter oscillator circuit.
www.americanradiohistory.com
+ve
707
PRACTICAL WIRELESS
December, 1965
BENTLEY
LTD.
ACOUSTIC CORPORATION
LONDON, N.VV.I
Suppliers to H.M. Government.
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NEAREST UNDERGROUND: CHALK FARM.
PLEASE
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5/6
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15/V10115412/11-6103 12/-
LOOSE OR BOXED. BUT MUST BE NEW
WE REQUIRE FOR PROMPT CASH SETTLEMENT ALL TYPES OF VALVES,
R514 12/8. RBI 17/8. 14486 17/13,
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.
18EA.1.1.8.1
16122.2.1.8.1 8/8.
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/,
113/2D 4/8. Q3/4 8/1.
18RA.1.2.8.1 111, 1,0116 13/.. P0124 12/6. 6133 10/& 1.81) 9/, 02E 5/9. C2v 9/-. 031.1 11/, 03B 14/8. 03V 11/-.
60 A 24032715v. 9/8. 100 A 400/275o. 12/6. 100/275, 8/-. 200076V. 4/-.
ELECTROLYTIC'S. Can types: 32 32:450v. N.. 50 x 60/350v. 8/-. 64 x 120/360v. 11/...
4/... 8 x 16/450A. 8/9.
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.
resistance 1/6.
Midget silicon rectifiers. TyPeS =100. Output 250 volts 4 amp. No larger than a shirt button. 6/6 each. Series limiting
32/360v.
3/,
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Term. ol bus/ !WA,- Cash with onier onq,. Pogt Tacking 44. Per dem. Orders ovcr 26 post free. No C.O.D. All ordershitcleared
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HI -FI PROJECTS FOR THE
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METERS (VOM & VTVM)
Demy 8ro
by Robert G. Middleton
Derny 8vo
160 pages
21/.
J
Net
WAYS TO USE YOUR HAM
TEST EQUIPMENT
101
by Robert G. Middleton
Demy 8vo
168 pages
21/.
Net
SOLID-STATE POWER SUPPLIES &
CONVERTERS
by Allan Lytel
112 pages
20/- Net
KNOW YOUR TEST METERS
Demy 8vo
(VOM & VTVM)
Denny
by Joseph A. Risse
8vs
NOVEMBER
first
time
working.
Instruction books
written
by Radio Instructors- anyone can build without
any knowledge of Radio or Maths. Superb alter
sales service facilities. Our designs are to the
highest specifications top quality is put first.
All tito include wire, nuts. screws.
hardware,
etc.
Money
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you feel on receipt
of the kit that you
are
unable to
_- build it, return It
within 7 days and
39/6
.IIII!iìi
li we'll
by
L
George Lawrence
G128
pages
;; }' x 2 }' x 1-. Specially designed
ferrite rod, 4 new Mallard semiconductors,
proper tuning condenser
radio --only
case,
proper plug -in
battery. Special reties plus regen,ra-
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circuit
gives
performance equal
to 6 transistor Radio
(even operates a
speaker). Amazing
power, superb tone
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.
-tunes into station
after station, home
and abroad.
No
or
earth
beautifully
any-
where at all!
II
`\\
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Only 39/8 plus 2/64. p. & p. Everythingincluding 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 semiconductors0A90/91, 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.
All parts available separately.
EDUCATIONAL ELECTRONIC CO. (EEPWS)
77 New Bond Street, Mayfair, London W.1.
TRANSISTOR AF & RF CIRCUITS
by Allan Lytel
by Alan Andrews
96 pages
18/-
Net
241.
Net
by Norman H. Crowhurst
Demy öre
96 pages
16/-
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Demy 8vo
SERVICING WITH DIP METERS
by John D. Lenk
Demy 8vo
128 pages
ABC's OF TAPE RECORDING
DECEMBER
TRANSISTOR SUBSTITUTION
HANDBOOK (Sixth Edition)
Demy 8vo
128 pages
12/6
£7/19/0
Solve your communication
problems with this latest
Transistor Intercom system (1 Master and
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
On/off switch. Volume controL Ideally eatable for
Office, Factory Workshop, Warehouse, Hospital,
Shop etc., to keep instant interdepartmental
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Size 6f in. x 4 }in.
96 pages
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ELECTRONIC SYSTEMS FOR
CONVENIENCE, SAFETY AND
by Edward A. Altslwler
Demy 8vo
256 pages
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Demy 8vo
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Special
The Imperial stereophonic 4 waveband
chassis has the most advanced specifications
yet offered in this country. There is a built in ferrite rod aerial,seven piano key buttons.
Long- Medium -Short and VHF bands. Complete with two 10' loudspeakers plus a
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Chassis only 29f gns.
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144 pages
NEW DEAL FOR AMATEURS
needed -works
RADIO CIRCUITS
S
by Thomas M. Adams
December, 1965
Every component is brand new. Accurate, tested
resistors. condenser+, components to give you
aerial
BASIC ELECTRONICS SERIES
WIRELESS
Modernize your Once. Shop, Warehouse, Workshop.
Surgery, Nursery and Home with this Latest two -way
Transistor Intercom conalnto of two unite, Master
and Sub. in strong plastic cabinets with chromium
stands. Elegantly' designed to nee as two-way Instant
communication system-call /talk /listen -between
two person anywhere Indoors or outdoors. Operatte
on one 9v. battery. Complete with accessories.
Ready to operate. P. & P. 9/8. Outstanding vales.
BATTERY ELIMINATOR & CHARGER, 27/6
The your Transistor Radio or Intercom from domestic A.C. mains and charge dry battery PP3 9v. them
boost battery's life many times. Unbeatable vales.
Save your pounds on batteries. P. & P1/ S. C MO.
lets with Ping, Lead and Snap cord.
Null price re ended Y not stated Is arse lags
WEST LONDON DIRECT SUPPLER! cmir/II
abigasMA 1iYlYS, &WW1 UM
ia
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This fabulous 'Empress' Hi -Fi radiogram
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only 23 gns this is the bargain of the year.
Chassis only 151 gns.
Special terms available of E3.12.6 deposit
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MD radio
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LONDON, N.14. Telephone: PAL 3733/9666
PRACTICAL
December, 1965
709
WIRFLFSS
and the intended application.
Obviously the layout will be
affected if rectifying and smoothing 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 maximum resistance position and a
o
3A meter in the battery lead,
switch on. A hum or low whistle
will probably be heard, due to
the laminations of the transformer vibrating at the frequency
of oscillation. If there is no output reverse either the 6.3V
Fig. 3: Switching for mainsi
winding or the 5V winding
battery arrangement.
whichever is the most convenient
to unsolder. When all is well decrease V R and check both output voltage and battery current
consumption until the optimum
ratio is achieved between the
two. It is emphasised that
with either of the transistors
case it would be necessary to ensure that the 6.3V
specified the input current should not exceed 1.5A.
heater winding was capable of carrying the extra
If the full 250V is not available with a load of
current, which might not he so in the case of some
12k12 then a lower output power must be accepted.
smaller transformers. As a guide it can be taken
The overall performance will depend to a large
that the winding's current handling capacity is the
extent on the suitability of the transformer and it
same as the maximum current available when the
might well be worth while trying various types
transformer is being used in the normal manner.
before the unit is finalised. If maximum battery
Finally it is always preferable to switch off the
economy is required when feeding a reasonably
battery supply rather than to suddenly remove the
constant load, resistance V R can be increased.
For higher outputs, say above 5W, an 0C26 load on the output in order that undesirable
transistor could be substituted. This has a inverse voltage peaks are not developed across the
transistor.
collector current upper limit of 3.5A, but in this
1
1
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 subscription 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.
PRACTICAL WIRELESS BINDERS!
The Pract cal Wireless Easi- binder is designed to
12 issues, but it will accommodate
hold normally
two additional copies quite comfortably.
A new version of the Easi- binder with a special
pocket for storing blueprints and data sheets is now
/6d inclusive of postage.
available. The price is
Order your binder from: Binding Department,
George Newnes Ltd., Tower House, Southampton
Street, London, W.C.2.
www.americanradiohistory.com
I
I
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 themselves -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
=
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.
101
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 condition 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 terminations 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
Slough, Bucks.
160 pages. Size 84in.
& Co. Ltd.,
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 diagrams of commercial American gear. In the 16page 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 construct 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
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.
= PHOTOCELL HANDBOOK
THIS latest publication covering the field of
solar and photocell devices is printed and published in the U.S.A., and therefore covers cells
manufactured in that country. However, International 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
PRACTICAL
December, 1965
K:34
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2/8
5/6
ATP7
AU7
66/BOB
15/-
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8078
DL.96
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B2134
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KM
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28/288CC 12/E90CC 10/E114e
2/6
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80/21524 12/6
EA.50
1/7/2173
F.ABtMO 6/EMS
8/6
EAF42 8/EB84
1
E891
8/EBC23 61013041
7/2BC81 6/RBF80 6/E1415
18Ì201-
086
6684
EPOS
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84
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87/6
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BT79
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2090
CV71
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2C91
110081
E0082
&0088
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ECF82
202142
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1
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Frequency
5 bands. Two Ifs
463 kc /s. Image signal
and
dB up to 30
30-60 Mc /s. Self- checking
Ms
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Carriage and Packing 30/ -,
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8/8 OK8OT 8/8
618
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6405
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VERY HIGH CLASS COMMUNICATION RECEIVER TYPE BRT
402E. 150 kc ¡s-385 kc /s., 510 kc /s-30 me /s.
301 -.
EVERSHED MEGGER CIRCUIT
TESTER. 2 ranges 0 to 1,00052, 10051
co 200,0000. With test leads, leacher
carrying
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12116
2/--Ple 8/0
12J6OT 8/6
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8/12047
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12807
4/12807 8/- 2ti84 1551/..
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128E7
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121.7
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2061
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21"
150-0 -1500 mA
0-500 mV
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3"
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'Projection type.
2
31"
31"
it
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A.C.
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22/6
19'6
45f29f32/6
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17/6
281241-
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together with power supply unit for
200-250v. A.C. Complete two chassis with
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output 2kw, average output 500w. Completely new with valves and manuals E65.
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6080
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THERMAL PLUS MECHANICAL
CIRCUIT BREAKER FOR A.C. & D.C.
I
amp. Protects against shorts
(instantaneous cut -out at approximately.
Current
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 battery receives the charge indication lights
indicate visually the high current or when
incorrectly connected. Meter incorporated. For 6 or 12v batteries. Mains voltage
200/240v A.C. Price E3 P. & P. 436.
A.R. 88D INSTRUCTION MANUALS, 20/-. P. & P. 2f6.
TELEPHONE HANDSET. Standard
G.P.O. type, new I2/ -. P. & P 2/ -.
NEW DHR. HIGH-RESISTANCEHEADPHONES. 14 -. P. & P. If6.
+
AR88D RECEIVERS. Fully reconditioned, 155, rebuilt models E85. Carriage
paid U.K.
Open 9 -9.30 p.m.
724A
9/6 955
17/8
5/8 36T
5/6260 6/- á5W4
6/6-301.0 10/- 3523
6Z4
6- 3524GT 6/7/6 352ß0T 0/4/8 7B7
8/4/3/3/-
7174
6/- 8321
6/- 83'1
8/8
7/8
8/6
6/-
CV1690
80/10/- 3BP1
601- 3FP7
3/- 3E01
161elS61
FP7A
7064
9/9 7158
á/2/7/6/16 /-
C.R. Tubes
B/- VCR617C4(11
128.17
2/8 6AM5
W- 6A1t6
P. & P. S/ -.
Fully tested 260. Carriage
51-
8/-
71- 84
1208
UBF80 6/8
UBF89 8/8
UBL21 11/-
4/8
UABC80 5/6
UBC41 8/1762
8/3
7/8/8
2/- 12BE6
12867
6,16
1802
/- 1902
2/6 60A7
4/- 68A70T 8/6 1903
BAQS
7/- 68K70T 4/- 1906
7/7/- 1907
4/- 6AQ5W 9/- 6807
4/- 68070T 6/- 1901
4/- 6A86
4/- 6A86W 9/- 88FOT 5/8 19111
81- 20P4
4/- òA8741 20/- 68117
6/- 2186
8/8 68.77
6/- BAT'6
7/- BBJ7GT 6/8 251ú0T
8/6 6A D8
60270
6/6 26Yß
5/- 6414
8/4/8 26246
13/- 88K7
4/8 6137
2/6 6BL7GT 6/8 2625
2/- 6B80
8/8 -626GT
4/- 68147
6/- 6BA6
66Q7GT
6/- 261)7
6/81- 6BA7
2/- 30
8/- 6BE8
4/3 0887
7/- 6U4GT 9/8 30012
7/- 6BJ7
6/- 30E5
6BQ7A 8/- 6V6G
3/6BR7
2/6
9/- 6V6GT 7/6 30FL1
81- 30'19
9/- 6VBM
12/6 fiBW6
3/8 30PLI
604
2/- OX4
22/8
8/-
TP25
15/- 1L4
51- iLAB
7/- TT11
6/- TT15
85/. ILCO
6/- TTR31 46/- 1L114
5/- TZ0520 4/- 1N21B
5/- TZ20
16/- 1E43
7/- U81
30/- 1E70
8/- 1E4
10/- U12/4
6/- 1E5
8/6 U17
8/- 184
8/8 U18
11/- 18.5
8/- U25
8/1T4
9/- U'27
71-
8/-
MG
6(60
UF41
6/- UF89
8/- áAAá108A240i- 4080
8/- U1A1
6/- 3A/48J 85/- 60H6
P1.84
8/8 U1.84
7C6
10/6021
80/5/6 3A1167/M
PM24A 6/- UU6
4/7/- 88
8CL6
9/- 708
26/7/PT15
10/- UU9
4/6/- 41MP
61)6
3/- 7C7
8/6 3B7
PT26H 7/6 UY'21
7E17
7/8 44Á/168x
-/8 3B24
6/PT2611 7/6 UY85
80/7/6/3 7Q7
6/- :31)6
4/- 6B5O
ó/6/- 21550
PX4
14/- V1120
4/3E29
60/- 6F6OT 6/9 727
PX26
4/6 501.60T ß/9/- V1507
4/- 7Z4
8/- 6F60
SI3Q4
7/8
"/8 53A
PY33
8122
8/6 V1924 20/- 3QSGT -/8/PY80
6/8 VMP45 12/8/- 37
6380
6/8 9D^6/3/8 68
PY81
6/8 VP23
4/8 9D6
6/9 6E12
8/- .'33v
PY82
6/- VP133 91- 3X2
2/8
5/- 1.246
3/- 6F'13
76
616
6/PY83
6/- VR99
12AH7
5I36/- 6F14
8/- 4L"27
41- 12A118 11/4/- 6F32
PY800 8/8 VR106/306/- 4D1
6/6
31- 12AT7 4/- 77
PZl % 9/- V R150/306/- 5A1730 5/- 65133
2/6 12407 6/- 78
P7.1-76 12/- VU33A 4/- 5.41740 5/- 606G
6/6
1/8 124X7 6/QP21
8/- VU39
8/- 5B261M 26/- 6H6M
10/12AY7
QP26
5/- VX3266 4/- SB264M 40/- 6J4WA 1018/6/- 12846 6/- 89
QP230 6/- VX8122 6/- 5826511 86/- 656
Cathode Ray Tubes and 8psveel Valves. AO U.K. ordere below P1, P. A P, II ; over 61. 3/-:
C.O.D. 2/0 extra Overseas Postage extra at cos
H.R.O. SENIOR TABLE MODEL
260,.
38118
W119
X68
X118
X146
Y63
Y65
P1.83
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 -.
CEIVER,
8/6
1/6
8P61
1/6
8P210
8/8
BT V280 40
PEN2UOA3/PL3B
7/6
from
::alibration (built -in calibrator). Stabilisation of supply and temperature compensation. 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 reception. Facilities for diversity reception.
E;ccellent checked condition, 239. Mains
P.S.U. by P.C. Radio 24.10.0 Carriage 30'20 -40 dB
16/16/8
9/PEN26 4/6 U0085 6/8
PEN46 8/- UCH42
PCL88
Mc's in
kcs, 2nd
protetting over 40
Ist 1.600
8/-
R04/1.250
MARCONI COMMUNICATION
RECEIVERS CR. ISO.
8/2
QVU4/7
6/s
v18124 61- SR46Y 9/7/6/- 6T4
8/- 5U40
4/8
8/8/- BV40
8/6
7/6 5X46
4/8/- 6Y3G
W21
6/- 8U2150A
MHLD810/10/- 1E7G
ML6
8/- T41
8/8 1F2
10641T
6/N78
16/- TP22
5/-
ELMS
RF50
EF52
1181131
11114
8/9
10/-
KL34
DA30 12/6
DAF96
DF,T25 16/-
10/-
8/-
KT88 80/KTW61 4/8
KTW83 2/KTZ41 8/KTZ63 6/9/M8100
M8142 12/-
4/6
6/8
8/9
2/9
8/7/8 FW4/a008/6
20288 10/- FW4/8008/8
1E01.86 10/- 0112360 9/EF38
3/4 01/371K19/11041
4/DBTS
7l- 060/20 6/8/- EP37
DET20 e/- 11E40
8/- 0180/241151-
077
221-
HTfi715;_
EF88
EL88
EL41
81.42
ELM
80/- Qelao/1S
711
WIRELESS
WIRELESS SET No. 52 (CANADIAN)
Complete station consisting of Transmitter. 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 accessories. Export. Price on application.
712
PRACTICAL
HIGH QUALITY
WIRELESS
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.
LOWER COST
BROADWAY ELECTRONICS
92 MITCHAM ROAD, TOOTING, S.W.17
Combine an Armstrong Tuner and Amplifier and you
have all the advantages of separate units, plus compactness, easier installation, and equivalent performance 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
Phone: BALham 3964
(four minutes from Tooting Broadway Underground Station)
l
-
EX- RENTAL TELEVISIONS
r>-
-
,
;'
'
14 in,
E7.10.0
12 months 3
17
in.
EII.I0.0
star Guarantee
* Valves
** Tube
Components
Coloured FREE LIST
Channels for all areas
I9í
Demonstrations daily
from our
large selection
Personal collection or
Insured Carr.,
--
in. 20f-; 17ín. 30/-
14
ONE YEAR GUARANTEED TUBES
REGUNNED
100%
Add IO'- or old tube. 21
Il0° -9916 +
refundable on
OLD TUBE. Carr
All
301-
1016_
Slimline 17 and
19 inch.
Export Postage 301-
In. 99/6
'%
ca.
17 in. 79/6
15,14
59/6
12 In.
EX- MAINTENANCE TESTED TUBES
17ií1. -355-
ARMSTRONG AUDIO LTD - WARLTERS ROAD-N.7
Telephone: NORth 3213
(1,
Most makes and types available.
HANDSET
S6
I Sí6
pair
Name
Address
12
PW 65
I4in. -I5f-
Guaranteed good picture.
Carriage 5f- extra.
TELEPH ONE
VALVES £1 per 100. Assorted T.V. and
G.P.O. pattern, House to
Workshop, Garage, Inter.
Office, etc. Works off any
small battery. P. @ P. 4/6
Phone
ILFord
6001/2/3
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/ -.
DUKE & CO.(LONDON)LTD.
621/3 Rumford Road, Manor Park, 1.12
Liverpool St.-Manor Pk.
mins.
www.americanradiohistory.com
-l0
Stamp
For Free
List
December, 1965
A
PRACTICAL
713
WIRELESS
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 conventional 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
Fig.
II
with a two waveband glass dial
the receiver cabinet, gives station
The on /off switch is combined with
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 carefully 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,
conjunction
mounted in
indication.
the volume
Complete circuit diagram.
E
www.americanradiohistory.com
714
PRACTICAL WIRELESS
All other holes SBA clearance
t
Sfe
7
11
December, 1965
Bend down
along dotted line
713.
Cut-out for
cord drive
_
_
D
E
`P
1"
44
171;
71;
212
Hole sizes t
.Bend
dia hole
A
14.
B
11 dia. hole
C
34 dia hole
dla.
E.
_ABA
hole
clearenee.
214
d wn.
dotted
line
lot¢
Fig.
2:
Chassis
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 manufacturers 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
drilling details.
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
715
PRACTICAL WIRELESS
December, 1965
TI/IAUDIO RDU/TY SffRIO71//RÎY
R.M.S. on each channel
A High Fidelity All Transistor Stereo Amplifier providing IO watts
hate INPUT SENSITIVITIES
retest Slullard Iran +Mors
OUTPUT (per channel)
Incorporation Of 1114. sell, outstanding
performance figures for 10 watts R.M.S. into 15
made possible the really
10 watts R.M.S. Into 15
of this brilliant design. Compare them with other leading ohms)
ohm load.
makes currently asallable.
watts R.M.S. into 3.75
not
NOTE Rated output is m watts R.M.S. (continuous) which should
hm load.
confused with 1.H.F.241. (momentary culses).
TOTAL HARMONIC
DISTORTION
Into
u.1á at 5 watts R.M.S.
0.3% at 10 watt° .15 ohm
load
R.M.S. 1.000 c.p..
DAMPING FACTOR 20
15
FREQUENCY RESPONSE
14 dB 20 -20 000 c.p.s.
HUM AND NOISE -tom.
CROSS TALK -42dB to --53 as
t
MAINS INPUT SELECTION
v 50/
SEMI -CONDUCTORS
(per channel)
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.
AC107
The Pre -amplifier is based
on the Dinsdale Mkll
(W.W. Jan. 1965)
Manufactured and Distributed by LINEAR PRODUCTS LTD.
VALVES
SETS
NEW!
TESTED!
185, 1T4. Y84, OVO DAF91
get of 4 for 15/ -. DAF96 DF96
1115
GUARANTEED!
DF91, DK91. DL93,
DEN
DLO6.
4
r
ÚL94,
24/6.
4/- TY86F 10/6.- 511414
918 ECF82
8/6
5/8 U25
12/8 ECF86 1019 N18
8/9
6/8 U36
7'S EC1135 8/- PC95
U47
8/6
8/9
4/0
ECH81 813 PC084 5/6 1752
3/6 DAF96
184
4/9 9BW6
1154
8/9
PCC89
9/6
613
919 DCC90 6/9 ECL80
8/9 10F1
185
2/6
U78
7/9 ECL82 6/9 PCF80 6/8
1/9 lOLD12 7/8 DF33
1T4
9/9
1/9 ECL86 8/6 PCl/82 6/9 UI91
19/6 I2AT7 3/9 DF91
2P
8/B
3/9 PCF84 7/9 ii281
61- EF39
4/9 DF96
619 O2AU7
3A5
10/9
6/3 PCF86 818 11301
8/8 EF41
5/6 12AX7 4/9 DH76
3Q9
13801
15/PC0801
9/9
4/9
4/- EF80
4/9 12K7GT 8/6 01177
384
5/9
11ABC80
5/- PCF802 9/9
12/8 EF85
516 12K8GT 8/8 UHe1
3V-+
6/8 PCF805 8/- UAF4z 7/9
"If EF86
4/6 12Q76T 3/6 DK32
51140
6/3 UBC41 6/2
412 00132
4/9 EF49
5230T 4/11 19B060 6/9 DK9i
2/6 PCL83 91- UBC81 6/3
8/- EF91
11/9 141C92
52.40/0T6/9 20LI
1/I PCL84 8/3 UBF80 8/6/6 EF92
10/9 11K96
6/30L2 8/9 20P7/6 PC185 81- UBF89 519
3/9 EF97
13/6 DL3:1
6AL5
2/- 20Pt
5/- EF183 8/9 PCL88 818 UCC84 8111,6 DL35
2/0 20P5
6AMr
6/6 PENA4 9/6 UCC85 6/0
4/I EL33
5/6 251.86T 4/8 DL92
6AQ)
5'8 EL38 11/8 PEN383 9/8 UCF80 8/8
41- 25U4GT11/e 01.04
6AT6
8/9 PEN36C15/- UCB42 71"
61- EL41
8/- DL96
4B46
416 30018
4/6 FFL200 17/6 UCH81 6/6
6/9 EL84
8/8 DY86
613E6
4/9 30F5
8/9 1701.82 7/3
il- 30FL. 9/6 DYA7 8/- EL95 5l- PL36
6B116
6/9 UCL83 8/9
8/6 PL81
6BJ6
5/6 301.15 10/3 EABC80 6/- E51:34
6/9
8/8 UF41
519 PL82
E51.44)
7/6
6BW6 7'9 30L17 12/- EAF42
4/6
e/- UF42
PL83
7/3
41- EMU
13/8 EB41
3/8 30P4
6F13
6/8
6/3 UF85
5/9 01284
2/- EM84
7/8 EB91
62'14
91- 30P12
5/9
6/6 PL500 141- UF89
6R76 148 30P19 18/6 EBC33 6/- E5187
U L41
7/3
7/0
PL80]
6/3
EY51
6/6
EBC41
9/6
30PL1
4/8
6K8G
L44
15/8/ PX25 7/9 FiUTA6
eK86T 7/6 30PL13 10/9 EBF80 6/- E Y86
8/6
PY32
8l9
6/9
9/6 300L14 11/. EBF83 7/6 EZ40
6P28
518/0 UL84
6/6 FY33
6Q70
5/9 351,66T 6/3 EBF89 5/9 E7.41
4/9
5/3 UY41
4/- PY80
4/6 ECC40 8/9 EZ80
e8L76T 4/0 35W4
4/5
5/3 UY85
4/6 PY81
6V66
3/6 35Z46T 4!8 ECC81 3/9 F.Z81
VP4B
1115lPY82
FW4/500813
6v66T 5/6 53KU 8/8 E0082 419 07.33 14/8 PY83
3/8
5/9 W76
7/418 ECC33
3/6 80
62E4
2/8/9 PY800 6I6 W77
12/6 ECC84 6/8 6Z37
6X56T 818 6083
24/8
8/8 TH210 9/6 Y70
5/8 KT81
9/3 E0085
10/6 AZ31
7B6
2/
4/6 EnF.O 7/6 M 11140015/- TTl"^;', 6/6 077
7/9 B'te
7B7
1A70T
1H5GT
1N5GT
24
718 7C5
7/3 7C6
7/9 7E17
719 CL33
5l9 CYO
4/9 DAC32
READERS RADIO
TORQUAY GARDENS
COLBERG PLACE, and at
85
STAMFORD HILL
LONDON
N.16. STA 4587
400
l
FOR
FREE-
operation
F.)
EXPORT ENQUIRIES INVITED
Tested
in
to.
satlefactorY
temperature of
50°C. (120
Designed and developed by the
Audio Fidelity Group of Companies.
ELECTRON WORKS, ARMLET, LEEDS:'
REDBRIDGE, ILFORD
ESSEX. CRE 7441
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 Theoretical 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
obtainable to order through any Retail
Newsagent (3s. 6d.)
Is
(Specimen Copy 3s. 6d.)
55 Victoria Street,
London, S.W.1.
valve 9d. extra. On 2 valves or more postage 6d. per valve extra.
Any Parcel Insured against Damage is Transit 641. extra.
Postage on
m.v. 33 ), r.p.m.
m.v. 78 r.p.m.
7
SERVICE
DAY
SAME
3.5
Pick-up Crystal/Ceramic
OR
IN
CABINET
STANDING USE.
IT ELIMINATES THE NECESSITY OF
MATCHED INPUTS & COMPLICATED
SWITCHING ARRANGEMENTS. IT
ALSO PRODUCES CONDITIONS OF
MINIMUM NOISE AT HIGHEST
SENSITIVITIES.
EQUALISATION
Gram. to std. R.I.A.A. characteristic.
Tape head to std. C.C.LR. characteristic.
SIZE 121. 54-x81'
Please send
WEIGHT 1211b.
SAE for
leaflet
FILTER (S.eep Cut)
KO', S Reis t, Kei -.
Pick -up Magnetic
Microphone 5 m.v.
Tape Head 2 m.v.
Aux. (Radio Tuner. Tape Rec.
etc.) 100 m.v. (Above sensitivities 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 employing latest materials and techniques
DESIGNED FOR EASE OF FITTING
)))
100-110- 120 -200-210- 220-240
_0 c.o.s.
be
1
www.americanradiohistory.com
PRACTICAL
716
BRAND NEW AM /FM (V.H.F.) RADIO
GRAM CHASSIS AT £13.13.0 (Carriage Paid)
WIRELESS
December, 1965
.Jft¢
SUPER 6
LONG & MEDIUM WAVE
TRANSISTOR RADIO
A quality radio available as a
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 pushbuttane4 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.
GRAMOPHONE AMPLIFIER
2-VALVE
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.
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
x 4'. Price 60/-. (P. & P. 61-).
i
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
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 foamlined box: motel for presentation. 15/- post la d
*
*
*
-*
*
BATTERY
Ì
ï
4
ELIMINATOR
t
t
t
¿
rectifier. For Coloro studio de.k only. Price 88.14.0 (go- P. A P,)
SELF-POWERLD
V.H.F.
TUNER CHASSIS.
Covering 88.95 Mc /s, Mollard permesbility tuner. Dime. 8 e 8 a 61n. high.
Valves ECC85, EAB080 and 2- EF89's
FULL! GUARANTEED AT RECORD LOW PRICES
MYLAR BASE
7in- Stand. play. 1,'200ft.
Long play, 1,800ft.
12/8
19/8
with metal
541x. Double play. 1,800ft.
22/6
rectifier.
Mains transformer.
Fully wired and tested ONLY 88.17.8
Od.
per yard.
PUSH -PULL O.P. AMPLIFIER
£5.5.0 (6/- Carr.)
Brand new 200 -240 A.C.
mains.
valves RE80. ECC83 and
2 -EL84
asBs, treble and vol. controls, with
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
BSR -17A14
GARRA RD AUTOSLIM
STEREO
AUTOCHANGERS
85.19.8
68.10.0
07.5.0
210.19.0
011.10.0
AUTOSLIM DE LUXE ATO
STEREO
Carr. 5/- each
l
'2,16:
EPSOK 50.000 o.p.v., 145 /- post
/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
71e.
BRAND RECORDING
TAP.:
lin. Double play. 1,200fí
8/8
14/-
22/8
42/8
75/-
..,
.,
8f8
4/11
7/8
GLADSTONE
RADIO
ELMS ROAD, ALDERSHOT,
Hants.
66
(2 minn.
from Stition and Boses.)
Andenhot 22240
CLOSED WEDNESDAY AFTERNOON
CATALOGUE 6d.
Rexret overseas orders cannot be executed
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/
Post
AMERICAN
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)
(cart. paid). Room dipole 12/6. Feeds.
d
IMPEDANCE
Falfy baht. Front panel 12} x lin. Chaavis size
RECORDER AMPLIFIER
105 x 5 x Mn. Valves
EF88, BOLOS and 2EL84. Controls (1) Mic. Vol. (2) Tuner /P.U. Vol.
(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
A
TRANSISTOR
MINIATURE PUSHPULL AUDIO
AMPLIFIER HIGH
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).
TAPE
Ì
*
**
£4.17.6
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
Two units to replace existing batteries.
prie..
For
*
*
*
r
p
p
*
*
for 2 / -.
PLANET INSTRUMENT CO.
NOW IN ITS 11th REVISED EDITION
. .
ELECTRICAL ENGINEER'S REFERENCE BOOK
A revised edition of this comprehensive thirty -three section standard 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 windings and design; electronic motor control; cold- cathode lighting, etc.
The "Progress" section is again entirely new and includes an authoritative 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
2s 1W) DOMINION AVENUE. LEEDS, 7
www.americanradiohistory.com
switch off and again check all wiring and components. 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
717
PRACTICAL WIRELESS
December, 1965
S1
Voiyme
On Off
Tuning
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
A.C.
V
`ì
Fixing bracket
for Cl4apc
mains t'
Fig. 3:
Top
chassis layout and wiring.
TC3
To
C14(b)
TC4
51a
To
C14(c)
Sib
Leads
A.C.
mains supply
black
from
Fixed
plates
L4
to
51
L1,L2
C
yellow
L
V1
0
"-To
A.C.
mains
Fig. 4: Under chassis wiring diagram.
www.americanradiohistory.com
718
PRACTICAL
To V1,pin1j, To
oscillator
pin8 of
(aerial)
pin 8
á
A
.
grid)
To
lr
To pin 8
/v \
COMPONENTS LIST
in 6
L2
S1c
plates VC1b
e
To
pin
1
of L4
To
R
47kí2
I
R2
pin? of L3
fixed
plates
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 protrude 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 searching 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 waveband, 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
LW aerial
until no further improvement
can be gained, when you should
find that the receiver is quite sensitive 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.
(blue range
1)
IOkí2
R7
R8
R9
47052
47k52
100k52
39052
R6
All 0",
10k0
RIO
Ikí2
2.2Mí2
RH
50052
470kí2
unless otherwise stated.
C
0.001µF mica 750V
RS
(oscillator
grid)
anode)
Resistors:
R3
R4
A.
(oscillator
To
pin 6
of Lt
h
(d
pp
t
fixed
aerial
via Cl
(mixer
of L4
To
S1b
To
Sia
aof L3
December, 1965
To pin 8 of L2
Lt
anode
To
WIRELESS
IW
Capacitors:
I
C2
C3
C4
C5
C6
C7
C8
C9
C10
paper
paper
silver mica
0.1µF
0.1µF
100pF
0.1µF
110pF
paper
silver mica 5%
silver mica 5%
paper
350pF
0.1µF
25µF
25V
300pF
CII
0.0IµF
CI 2
CI3
CI4 a,
CIS
25µF
5W
5W
electrolytic
mica
paper 500V
electrolytic
25V
0.005µF paper 500V
b, c 32+32+814.F electrolytic
0.25µF paper 750V
VC1a, b
TCI,
300pF twin gang
2, 3, 4 50pF compression
trimmers.
Inductors and Transformers:
LI dual purpose coil, range Blue
L2 dual purpose coil, range 2Blue
I
Denço
L3 dual purpose coil, range I Red (Clacton)
Ltd.
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
V2
I5D2
8D2
I2A6
V3
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 *in., glass dial, back plate,
pointer, drive spindle (rear drive), drive drum,
nylon cord, tension spring, etc.
I
M.W
aerial
(blue range 2)
LW. osc.
(red range
MW osc.
(red range 2)
1)
8)
Ü
To
x
To
To S1a
To S1 b
Fig.
Sta
To
51b
To
C5'
S1c
To
To Std
6: Details of coil connections.
www.americanradiohistory.com
S1c
To
S1d
To R4,
C5
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
39/6
full medium waveband.
45/BOY'S 4 TRANSISTOR MODEL
6 TRANSISTOR MODELS
In plastic case. 4 x 2¡ x lin. with 21in. speaker.
Uses PP3 type battery Tunable over full medium
59/6
waveband.
2 Waveband (Long and Medium) Model size 5 x 31 a liin..
89/6
cream/black plastic case.
FAMOUS MAKE TRANSISTOR RADIO
THE "STELLA"
7
transistor portable radio. Long.
Med. and Short wavebands. Fitted
tone swatch and sockets for per-
and external
sonal earphone
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.
£9.19.6
P. & P. Sf
WIRECOMP'S PRICE
WONDERFUL BARGAIN FROM RUSSIA
THE "SOKOL"
7 transistor radio covering full Medium and Long wavebands
with exclusive rechargeable battery which can be recharged
on PP3
from any 110/250 v. A.C. mains supply. Can also overate
type dry battery. High quality P.M. speaker. Ivory and black
for
plastic case with metal trim-size 6 x 31 x 1:- in. Socketscase.
real leather
external aerial and earpiece. Complete with
dry battery, rechargeable battery with mains connector, and
personal earpiece.
WIRECOMP'S PRICE
£6.9.6
p. & P. 2x6
AMBassador
7115
Early closing Thursday
323 EDGWARE RD., LONDON, W.2.
All Branches open
all
719
PRACTICAL WIRELESS
December, 1965
day Saturday
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
Receiver
Portable
Transistorised
made to the highest professional standard. Comprises 7 Mullard Trans. '
plus Crystal Diode. 350 milliwatt output 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.
separately
parts
Ail
MAY BE BUILT
£5.19.6
p
FOR
bought,)
p. & P. 4/6 extra. (Circuit diagram 2/6, free if all parts
wood cabinet
Also De Laze Model with superior PVC covered
and full view tuning dial. ONLY £1 EXTRA. AB, parts sold
1
'
ersol
separately. Battery 3/9 extra. P. & P. 4/6.
SINCLAIR SUPER MINIATURE POCKET RADIOS
with
THE MICRO-6. Pocket radio only N /,, x l'l,o x fin. Completeonly.
earphone and detailed construction data. Can be built for
59/6
THE SLIMI.INE. The new 2- transistor pocket radio size
23 x 11 x lt1n. l'an be built for
only
49/6
INTERNATIONAL BRAND TAPE -Fully Guaranteed
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.
15/17/6
-
ACETATE BASE
3in
10 /15/-
8/6
11 /8
am
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
separate
four
mixing volume
I
l
]
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: Historical Outline - The Colour Signal - The
Chrominance Signal - Colour Transmission - Receiving the Colour Signal Domestic Aerial Systems - The Receiver
Block Diagram - The SECAM Receiver
etc. 128 pages. 58 diagrams.
from ALL BOOKSELLERS
16s. by post from George
or, in case of difficulty,
Newnes Ltd., Tower House, Southampton St., London WC2.
NEWNES
controls. High
gain of 10 milli volts makes it
suitable for all
types of guitare
and microphones-
Bopa-
ate Baas and
Treble controls.
i Raster
gain
control. Tremolo speed and
depth controns.
Remote tremolo switch socket. 7.5 and la
by Terence L. Squires, A.M.Brit.I.R.E.
-
12/6
378 HARROW RD., LONDON, W.9. cuN;9530
BEGINNER'S
GUIDE TO
COLOUR
TELEVISION
.
4 /11
7/6
10 /-
..
31n.-300ft.
5in. Long play. 900ft
35/5ifn. Long play. 1,200ft.
22/6
7in. Stand play, 1,200ft.
45/7m. Lon : play. 1.800ft.
12/6
P.V.C. BASE.
lin. Long play 1,800ft.
19/6
5in. Stand play, 660ft.
lin. Double play, 2,400tt. 23/afin. Stand play 840f f.
71n. Triple play, 3,600ft.
58 /8
I'. & P. i/- extr per ree:. 4 reels and over Post Free.
Your complete basic guide devoid of mathematics
and circuitry .. .
I5s.
3/8
150ft.
3in. -225ft
151-
ohms outputs.
50
and
90
watt
valves
ECC83,
valves
ECp83,
;Ziii.
15
watt
ECC83, 50E83. E1.3í, f:I. i,
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
£1,.10,0
watt ess treniolo
816.17.6
watt with tr,m lo
214.10.0
watt less tremolo
613.17.6
15 watt with tremolo
£11.10.0
15 watt less tressais
Descriptive leaflet free, stamp appAdd carriage 10 /- an}, amplifier.
reciated. Suiteble speakers, Bakers 12 Guitar L.B. 0 gns. Bakers 15'
5o
30
30
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.
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720
PRACTICAL WIRELESS
OUR
"TELSTAR"
EVER- POPULAR
I
-VALVE
FOR
December, 1965
VALVES
-
SEMI
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
SEND If- in stamps
FOR YOUR COPY
Trade catalogue available which
is of interest to schools, research
establishments, etc.
SEMI CONDUCTORS
te
Transistor Portable
complete with battery.
The "POP -6"
case and earpiece.
P
Really palls in chose pirate stations.
62/6
&
P.2/6
waveband. No batteries needed. Complete with earpiece.
9/11
ONLY
P.
&
Oliver
ACI13
AC154
AC 55
AC 156
AC157
AD140
ADT 140
AFI14
AFI I5
AFI16
516
40-
I
AFI
5/6
V25fIS/I
f.
10/6
101-
9/6
Y7
AF124
AFI25
AF126
AF127
ASY28
BY100
I
II/-
10/6
10/-
BYIf4
MATI 00
9/6
6/8
7/6
SI-
9/6
IV719
BBC2 (625 LINE) TV AERIALS
fAHOUS FOR THIRTY YEARS for
SHORT-WAVE EQUIPMENT al QUALITY
KITS
9
element
OA6
OA10
0C42
0C43
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SI-
I0161616
21-
0,481
0A9
2/2/2/-
0A85
0A90
51-
4/6
4/3
5/6
16f-
0075
OC76
0077
0081
0033
0014
2/2121-
9151-
OC45
OC70
OC7I
OC72
OC73
5/6
0A70
0A73
0A79
61-
0A95
316
0A200
3/6
0A210
APOAZ203 7/6
OAZ204 7/6
5/6
6t,
9/6
5/6
4/-
0C139
516
81-
OC170
OCI71
OC200
6/6/7/6
OCP71
25/-
K.V.A. ELECTRONICS
PM.)
3b Godstone Road, Kenley, Surrey
LOD 2266
(Dept
technician who
is servicing
electronic organs.
by C. R. Pittman & E. J. Oliver
Postage
Postage 1/-.
TROUBLESHOOTING WITH
TEST METERS (VOM & VTVM),
by R. G. Middleton. 211-. Postage It -.
WORKED EXAMPLES IN ELEC-
TRONICS
CATIONS,
101
TELECOMMUNI-
&
Vol. I, by B.
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TEST EQUIPMENT,
H.A.C. were the original suppliers of ShortWave Receiver Rife tar the amateur constructor. Over 10,000 satisfied customers---.
including Technical Corteges, Hospitals,
Public Schools, R.A.S'., Army Hams, eta,
IMPROVED 1965 RANGE
1 -Valve model "OR", compote kit, Pries 34/6
Customers say: Tiefiuiteiy the best one valve B.W. kit ave:labia at any pries. This
kit contains all genuine Short-Wave components, a drilled chassis, accessories and full
metasctions. Ready to assemble and of
coon, as all our products. Puny guaranteed.
FULL RANGE of other kits atin available
including the famous model 'E'. price 77/ -.
Before ordering rail and inspect a demonairatios receiver or send for a deecripti.r
catalogue and order form to:-
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(Dept. P.W ), 44 Old Bond It., Loadas W.1
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WAYS TO USE YOUR HAM
and Z.
F.M. AERIALS
B.B.C. (Band 1). Telescopio loft 21/ -. External
B/D 30/-LT.V. (Band 8). 3 Element loft array 25/ -. 5
elemen t 35/ -, Wallmoun ting, 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.
VHI1 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.
SERVICING
ELECTRONIC ORGANS
A practical guide for the service
BASICTHEORY& APPLICATION
OF TRANSISTORS. U.S. Army.
ment 70 /-. All high gain units have
special Multi-rod Reflector. Low loss
CO -axial cable 1/6 per yard. VHF trensietor pre -amps from 75/-.
-
0A5
OAZ207 7/6
OAZ208 516
OC35
12/-
8/6
30/-
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 element 72/-; wide spaced high gain, 11 element 80 / -; 14 element 87/6. Loft Arrays,
7 element 32/6; wide spaced high gain, 11
element, with Tilting Arm, 62/6; 14 ele-
ITV
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103 LEEDS TERRACE, WINTOUN ST,
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SHORT-WAVE
BBC
8/6
MATI20
MATI21
NKTI42
(OC44)
NKT404
(OC35)
ALPHA RADIO SUPPLY CO.
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Export Trade Enquiries Invited
Mast Mounting Arrays,
MATIOI
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R.C.S. PRODUCTS (RADIO) LTD.
Il
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READY TO USE POCKET RADIO
Covers Medium
RECTIFIERS
56 PAGES
ALPHA
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The ideal economical and safe way of running any Transistor
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ith special adapp]
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reactivate your existing
All "Power Pius" units are cornPP3 type bah
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pletely isolated from mains by
tery.
double wound transformer ensuring 100% safety.
P. & P. 2/6.
6
METAL
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NOW AVAILABLE
speaker use. Total Building
All parts Costs 35/P. & P. 2/available separately
42/6
CONDUCTORS
by
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TRANSISTOR RADIO SERVICE
MADE EASY, by W. Lemons. IS / -.
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HANDBOOK,
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25f -.
1%.
WIRELESS FOR BEGINNERS,
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181 -.
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TRICAL REPAIRS, by R. C. Norris.
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COMPLETE CATALOGUE
It-.
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19 -21
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Open 6 days 9-6 p.m.
December, 1965
PRACTICAL
WIRELESS
721
No.2
PLYMOUTH RADIO CLUB
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
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 beginning 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 .callsigns. 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
T
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 Morse
chewing" and informal discussions.
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
-
Le; t to right Clan "D" Wavemeter,
Club station
CR100, K.W. Geloso Converter, K.W. Vanguard.
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
Basically the receiving side
the photograph.
comprises a " hotted-up" CR100 running from a
KW /Geloso -converter at 4.6Mc /s and the trans-
www.americanradiohistory.com
722
PRACTICAL
WIRELESS
December, 1965
specially selected sites high up on
Dartmoor during a few weekends.
The clubroom itself is situated
in Virginia House Settlement,
where we have our own accommodation. 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 BarbiA recent quiz between Torbay A.R.S. and Plymouth R.C.
can and, indeed, inside the original walls of the old " Sudtone "
milting side a KW Vanguard. However, a great
which appears in the " Domesday Book " (a little
deal of work has been put into designing the
before radio!) and within easy walking distance of
station to our exact specifications. The console
the " Hoe" and we often go up to see Drake
operating position was built with ease of operating playing bowls when operating /m!
over long periods in mind and all operations can
So much for the past and present but what of
be performed by using the fingertip controls immethe future? Plans have been drawn up for a new
diately in front of the operator. The transmitter/
building with a radio shack and station drawn up
receiver set -up has been modified for full break on by the architects to our specifications. A lattice
c.w., with switching handled by " Londex " relays,
tower will be built into the roof, an earth mat into
and for single switch control on 'phone-sidetone the floor and the shack will be separated from a
is, of course, incorporated for the former mode.
laboratory by a glass partition through which
The "Skywire" arrangements comprise a G5RV
measurements and readings can be made on the
fed with open wire tuned feeder for the " 34' downtest equipment on the laboratory bench. The
lead" section and then with low loss coaxial present station will be used to train novices, whilst
cable. For the h.f. bands there is a G4ZU beam
the new equipment will probably be on the lines
fixed on the east.
of a Collins "S" line or its equivalent in about
Operations are roughly half 'phone and half five years' time, when we can reasonably expect
c.w. and there is a great deal of activity on all
these plans to materialise!
bands, especially in contests during the winter DX
In the meantime we intend to fit s.s.b. to the
season. The R.S.G.B. National Field Day is a
existing station by purchasing an SB10U which
must every year and a highlight in the Club
will be built by our technical committee and will
calendar. A certain amount of other portable enable the call -sign " G3PRC " to be broadcast
activity is indulged in-the station is operated at even further than the five continents and some 80
the aforementioned annual picnic and also from 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)
L2
L3
L4
L5
L8
tap 13t
from
earth
at
50t
5t
150t
lot
34
'34
34
34
42
34
L1
swg.
Wound
over
L1
7Ç
Wound
over
L3
dia iron cored coil
Wound
over
L5
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 transistor radio which is screened by placing it inside
a biscuit tin!.
www.americanradiohistory.com
PRACTICAL
December, 1965
INCREASE YOUR EARNING
POWER AND JOB SECURITY 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 complete 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. Includes 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
No. 400.
VALVES
NEW
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.
PL36
8/8
1/9
OA2
3/9 E1391
PL61
6/6
6/3
1115
4/- EBC41
PL82
5/1S5
5/9
3/3 EBF80
PL83
5/11
5/9
1T4
1/9 EBF89
PL84
8/ECC81
3/3
3S4
4/3
PY32
4l6
8/6
3V4
5/- ECC82
PY33
8/6
4/6
61C7G
1/3 ECC83
PY80
4/9
5/3
6101G
3/3 ECC85
PY81
5/5/9
607G
5/6 ECF82
PY82
5/9
4/9
6V6G
3/- ECH35
FY83
5/3
7/9
20P3
10/6 ECH42
PY800 5/11
20P4
5/6
13/- ECH81
U25
8/201'5
11/6 ECI.80 5/11
U26
8/6
816
30FL1
9/3 ECL82
9/6
FCL86
81 11191
30L15
9/9
10/6
'30PLI3 10/- EF39
3/6 U301
0801
14/9
5/9
35L6GT 5/6 EF41
85A2
5/9 EF80
4/3 UABC80 5/AF
12
6/11
EF85
416
CL33
8/6
UBC41
6/DAC32
6/6
6/9 EF86
UBF80
5/6
DAF91
4/3
3/3 EF89
UBF39 5/9
2/8
DAF96 5/11 EF91
DF33
6/9 UCC84 7/11
7/8 EL41
UCC85
6/FL84
4/6
DF91
1/9
UCF80 813
EY51
DF96
5/11
5/11
UCH42
7/DK32
516
7/- F.Y86
UCH81
6/5/6
DK91
4/. F'7.40
UCL82
7/3/9
DK92
7/9 E780
UCL83
8/6
DL96
6/3 EZ81
4/3
UF41
6/6
DL33
5/6
6/6 PCC84
UF89
5/6
DL35
9/8
4/9 PCC89
UL41
7/6/3
DL92
4/3 PCF80
UL84
4/9
DL94
815/- PCF32
UY41
3/11
PCF805
DL96
8/5/11
UY85
419
DY 86
6/3
6/3 PCL82
ll9
DY87
9/- WTT
7/3 PCL83
Z77
2/6
7/8
EABC80 5/6 PCL84
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.
world of electronics!
extra.
Office address. no
ELECTRONICS COURSE
45/-
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 resortThousands M readers
ing to comic strip methods.
of this magazine have taken this coerce and enjoyed
Why not you? Clip this
every minute of
coupon for your free trial offer now!
A
723
WIRELESS
BERNARD
GERALD
83
caner,.
rPLEASE GIVE,'
I MEASOLON I
ELECTRIC
SOLDERING I
IRON FOR
I
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
Solon are the best soldering
4
- irons. They last for years and
all parts are replaceable.
But remember, do say Solon
Ç
-'§
al
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.
-
,
OSBALDESTON ROAD
STOKE NEWINGTON
LONDON Nib
D
it...
-
The 25 watt
Solon is a good
standard iron for
radio and
electronic work,
being light and
easy to handle.
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 standard reference. Features 264 pages, 157 illustrations,
bound in cloth. An excellent book now offered for the
1ìr -t
N
'
UNCONDITIONALLY GUARANTEED TO
GIVE COMPLETE SATISFACTION
mss t" returned within
Aug .,,sire o
to
du,
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l
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chase price.
IF YOU SEND CASH WITH ORDER WE WILL
7
O
INCLUDE A FREE BOOK worth 4/6 to 5/- if
bought separately. By sending rash you reduce
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* * *
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No. 19
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commencing not ater than 10 days after delivery.
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money if I am not 100;, satisfied and I return the book within 10 days.
Please send me the free book(s) I have ticked.
Electronic Gadgets Book
Oscilloscope Book
Transistor Book
Name
HOLE PUNCHES
Instant Type
" diameter
Screw -up Type
...
B8A, B9A...
B7G
a-
...
...
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diameter Int. Octal...
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.,
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-rub"
2y"
6110 ea.
...
44" diameter Toggle switch
816
816
91.
916
1012
,.
,.
i
1314
1612
in the U.K.
Radio Instrument Book
LONGMAN
GIPSY ROAD
&
LTD.
WEST NORWOOD, S.E.27
Tel. Gipsy Hill 5000
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T
A 65 watt model
with a round
pencil bit for the
handyman,
especially
suitable for
wiring
connections
18110
2118
2414
3312
Now supplied by:
TOMPKINS
1
I0'8
II18
...
...
Complete Set £9.3.6.
No extra charge for postage and packing
Meter
237
Address
.
"''
and similar
lightwork.
i
'SOLON
724
PRACTICAL
WIRELESS
December,
1965
ANOTHER SINCLAIR
The world's first
pocket -size FM
Tuner! Receiver
COMPLETE WITH
TELESCOPIC AERIAL
POLISHED AND
BRUSHED TWO -TONE
ALUMINIUM FRONT
PANEL
SPUN ALUMINIUM
TUNING CONTROL
ONE OUTPUT FOR
TAPE AND HI -FI
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.
ONE OUTPUT FOR
PERSONAL LISTENING
ANYONE CAN BUILD
THE - SINCLAIR MICRO FM
All you need is a small electric soldering iron (preferably 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
www.americanradiohistory.com
COMB
T&
PRACTICAL
December, 1965
725
WIRELESS
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
Ilse
7 TRANSISTOR SUPERHET FM TUNER/RECEIVER
TECHNICAL DESCRIPTION
THE SINCLAIR MICRO FM
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 -contained receiver. A.F.C. "locks" on each station automatically. THE SINCLAIR 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 HIGH LEVEL AUDIO OUT contained standard battery.
PUT-9V peak to peak
TUNING RANGE-87.5 to 108
CONSUMPTION -5mA
Mc/s
SENSITIVITY -Typically 3 microSIGNAL TO NOISE RATIO
volts
30dB at 30 microvolts
is a seven
it as-
AN P. M. TUNER
FOR YOUR TAPE
RECORDER .d
-
AUDIO OUTPUT -300mV
prox. from 25K ohms
ap-
THE GREATEST VALUE
AUDIO
FREQUENCY
PONSE-10 to 20,000 cis
IN QUALITY
THE COMPLETE KIT OF PARTS for building the
SINCLAIR MICRO FM including extend ing aerial, 7
transistors, case, tuning dial, aluminium front panel,
lightweight earpiece, plugs and sockets and instructions costs only
GUARANTEE
RES-!-
Id8
FM EVER
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
www.americanradiohistory.com
AS A SELF
-
CONTAINED
POCKET P.M
RECEI VER..
PRACTICAL
726
December, 1965
WIRELESS
MORE UNIQUE DESIGNS
FROM
BRILLIANT PERFORMANCE ADVANCED CIRCUITRY EASY
SINCLAIR X-20
WATT
INTEGRATED 20
MODULATED AMPLIFIER
20
PRE -AMP
AND
OUTPUT
powerful hi -fi amplifier for its
R.M.S.
WATTS
The most
size in the
WIDTH
PULSE
world
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 refreshingly 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
By the use of Pulse
ventilating problems.
** Output
transistors
- silicon
epitaxial
square wave
* Constant
* amplitude
95% conversion efficiency
output
quality
re* Superb
liability
IdB
* Totalto harmonic ±distortion
watts
** -0.1
Input sensitivity - ImV
into
ratio* better to
* Power atrequirements
mA
12
stage
planars
at
and
20
20,000 c/s
% at IO
R.M.S.
5k13
Signal
SIZE
f8l4 1 x 3 z"
4
x1'
noise
than 70dB
36V d.c.
700
ohms
into
* Output
watts R.M.S. music
7.5
20
power
IS watts R.M.S. con -
ti
into
ohms
* Output
watts R.M.S. music
1S
15
value
IO
watts R.M.S. coo-
ti
guitar or
* amplifier
low-pass filter
* Built-in wide
tolerance
output
* Add
volume
control, mono or stereo,
to choice
* built evening
P.A.
Makes ideal
ensures
load at
cone
system
Easily
and
in an
SUPERB QUALITY AND POWER
FOR SUCH VERY SMALL OUTLAY
weight
only
£7.19.6
Complete kit of parts including
transistors and X-20 manual
in sealed carton
X-20 Power Pack
Built and tested with
sufficient to drive
7
X-20 manual in
two X-20's
sealed carton
41 ozs.
-'
£9
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.
sinlair
-6
£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.
COMBERTON, CAMBRIDGE
www.americanradiohistory.com
COMBERTON
r
682
Decem7er, 1965
727
PRACTICAL WIRELESS
SINCLAIR
TO BUILD
GUARANTEED
SI CLAIR MICRO -6
smallest radio
of its kind in the world
The
flow about you ?
Everybody's building it
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
SIX -STAGE
CIRCUIT
LUXEMBOURG
COMES IN LIKE
A LOCAL
FANTASTIC RANGE
AND POWER
medium waveband for easy reception of Luxerrvbourg, 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.
Amazing 6 -stage circuitry
A.G.C.
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.
In
EASILY BUILT IN
AN EVENING
PLAYS ANYWHERE
L
Ist A.F.
Amp.
2nd R.F.
Amp.
5
CELL
Type ZM.312 (2 required) each /II.
Pack of 6 10/6.
"Transrista" Black nylon strap for
wearing Micro -6 on your wrist 7/6.
1
J2nd A.F.
Amp.
Amp.
R.K., Preston, Lancs.
FULL SERVICE FACILITIES AVAILABLE TO ALL SINCLAIR CUSTOMERS
GUARANTEE ORDER FORM`
ADDRESS
I
3rd A.F.
Micro -6 builders write
Ouarant¢¢
Should you not be completely
satisfied with
L
-
I
NAME
value
Detector
"I
little instruments."
Please send me
for which
ej
I
All parts including M.A.T.s, case, dial,
lightweight earpiece and beautifully
detailed easy -to- follow 8 page instructions come to
MERCURY
Amp.
ans highly satisfied with this kit which receives most stations on the medium wave with
remarkable volume apart from the fact that this is
M. A., Sheffield G.
signal area."
a bad
"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.
am no longer the youngster that assembled radios before
W. J. R., Warwick.
the B.B.C. was born.
"Performance easily surpassed expectations. Luxembourg and
AFN were loud and clear and many continental stations could be
R. S., Northumberland.
heard at adequate strength including Moscow.
"Having been a transistor fiend for the last eight years, must say it is the finest
little set I have ever constructed. Please send one more of these marvellous
WEIGHS LESS
THAN I oz.
MALLORY
let R.F.
enclose Cash /Cheque /Money Order
s
d.
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
AERIALS
ALL TYPES OF TV /FM AERIALS
AVAILABLE
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.
BBC
1
J. R. R. BAKER
35
St. Mark's Road, Windsor, Berkshire.
TAPE RECORDERS,
TAPES ETC.
-
caster.
SOUND RECORDINGS
Buy top brand
A UNIQUE TAPE.
lin. 2,400 ft. 25/, 51in. 15/. P. and
p. 1 at 2/-, 2 at 2/9, 3-6 at 3/6. Bargains in all sizes. S.A.E. for list.
E. C. KINGSLEY & CO. LTD., 93
Tottenham Court Road, London, W.I.
RECEIVERS & COMPONENTS
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
(continued)
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.
50
to
Advertisement
addressed
Manager. "Practical Wireless,"
Tower House, Southampton SL.
London W.C.Y.
RECEIVERS & COMPONENTS
(continued)
MARCONI CANADIAN RECEIVER NO.52
Broadcast. Magnificent 10valve
rein
ceiver
three swit.0
ched wavebands covering 1.7516 Mc
(19
/s
-
170
u
s
TRANSISTORS, new, Red Spot and
White Spot, 28/. per 100 (minimum
metres).
G3LMR, 113 Groby Road. Gleaneld,
stal cali-
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,
TREASURE HUNT!
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.
packete post free. Relays, thousands
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.
4
of
R RADIO
NABEl?
&
T V SERVICE
Dept. P.W.
STREET, RAMP,
Telephone 465
LAM.
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 enSALVAGE VALVES
quiries
&ehiset M
Baasisllo Sr
%eyl
I
3
valve cry-
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
goods
CANADIAN MARCONI 52
Few only at 09.10.0
RECEIVERS
Carr.
20/-
MAINS POWER UNIT 02.10.0
Supplied with Outer Case, Handbook and
Range 1,75 -16 Mc /s.
Circuit.
Set has Crystal Calibrator, Speaker, etc.
V.H.F. RECEIVER. PYE P.T.C. 114
65 -100 Mc¡s 12 Volt D.C. Supply
is an
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
I
I
Receiver or Transmitter, exceptionally
good for Mobile Top Band use. This
American version being well noted as
far superior to any other. GUARANTEED BRAND NEW, only 20/ -, Post 7/6.
Instructions supplied.
JOHN'S RADIO
OLD CO.OP WHITEHALL ROAD
DRIGHLINGTON, BRADFORD.
SPEAKER REPAIRS, cones fitted.
L.
Satisfaction guaranteed.
S.
REPAIRS, Pluckley, Ashford, Kent.
20.0 -20
2tin. movement.
DIRECT TV REPLACEMENTS LTD.,
2.5 mA. full scale
UNMARKED, UNTRANSISTORS,
TESTED, 40 for 10/ -, p. and p. 1 / -,
&
p
paid.
Leicester.
Guaranteed Brand New in original carton
Shipping
Amateur, This
RECEIVERS & COMPONENTS
Post
GDPsy Hill 6166.
as -new
to
condition. Receiving 3/- each, transmitting 4/-. Post 6d. per valve.
Restore performance of your equipment at minimum cost. Send stamp
for leaflet. G IM I IOTT, 3 Sandgate
Ave., Tilehurst, Reading, Berks.
EUSton 6500.
quantity either type).
'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.
REACTIVATED
VALVES
New H.fgh -level
TAPE TO DISC
Cutters, 45 r.p.m., 21/ -. S.A.E. leaflet.
DEROY, 52 Hest Bank Lane, Lan-
R
December, 1965
PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS
728
d-fiectlon, 3 stud
switch
controls
0.10. 0400 ohms,
0 -Ind.
Complete
In carrying case
with Instructions,
45/.. Post Si-.
Tubular steel
TELESCOPIC AERIAL MASTS.
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
largest stockists of TV Components
in the U.K. Line Output Transforme 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,
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
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
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
www.americanradiohistory.com
West Norwood, S.E,27.
1
only)
Telephone:
Worthing 9097
40/42 PORTLAND
ROAD. WORTHING
December, 1965
PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS
RECEIVERS & COMPONENTS
WANTED
FOR SALE
(continued)
(continued)
MIN. JACK SOCKETS, 5/- doz. Coaxial 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.
.nlinuedl
SOLDERING -IRON
ELECTRIC
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
GNS.
4
LEE ELECTRONICS
400 Edgware Road. Paddington 6521
liar, *fai)e
Send for Free
at abash
IIAM:11EItI'l'E
*
and over
9,6
WANTED
VALVES ONLY
Must be new and boxed
Payment by return
WILLIAM CARVIS LTD.
TRANSISTORS
Il- each. Red or White
I
or
Olive,
m
Metallic Black.
Mon. to Fri.
direct from the
27- each.
0A90,
103
North Street, Leeds
7
Spots.
240rn° ELECTRIC POWER
®from
Wl,)
OC 169, 0C200.
ANYWHERE
41- each. AFII4, AFII5,
AF 117, 0C170, 0C171,
AFII6,
XA 103,
XAII6, XBI02, XBI05, XCI21,
XU6I I.
Walt it 15015 271wBt
In mlvleox.
roll) 10015 In1 rl)
uni,nsil ar/DC IIICnitlt Inuirmilitylus
wasteful Halo. 1,11, o1218 s scrrnlitt.
Sen/
µ'
01e51 enclore
lut 91111lelnlsl
'SOIxrinC ?AMDDCll,
XA 102, X8103,
0C430,
0C44, 0C45, 0070,
0071, 0081, OC8ID, XAI51,
XBI04,
XCIOI,
XCIOIA,
all
Irpn 11t smut
101,
MISCELLANEOUS
31- each.
CAR BATTERY
AMERICAN DYNAMOTOR UNIT
12
XA
XAIII, XAII2,
V10 /IS.
FINNIGAN SPECIALITY PAINTS (PW)
Mickley Square. Stocksesid. Northumberland.
!'boor: Nihl.k,t!eld '1_ISB
W
P.W.)
heal.
P.W.
219.
Blue.
Return of post service.
From yon, component shop
manufacture,:
LTÜZ
60
*
-
CnSoare:
Tape Recorders and Tapes, Watches,
Toots, any quantity. S. N. WILLEITS,
16
New Stree-.
West Bromwich,
Stalls. Tel 2392
Pawsons Road Wed Croydon.
WANTED: Old Eddystone Short Wave
Components and Battery Sets. Box
With 41ft. Safety 3 -Core
Indispensable for
every
home
handy - OVL
man. A boon to model
makers and a necessity
for every wireless enthusiast.
Offered to P &
you at this new amaz1/mg price.
C. H. SERVICE,
(Dept.
Limes( 11511 Lane. Tatsnelrl.
use.
flex.
URGENTLY WANTED: New modern
Valves. Transistors, Radios, Cameras,
DAMAGED AVO METERS wanted,
Models 7 and 8. Any condition. Any
quantity. HUGGETT'S LTD.. 2 -4
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
HAYNER PATTERN BRUSH PAINT FOR
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THE PATTERN IS fN THE TIN
ALL YOU DO Is BRUSH IT ON!
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3/6
35/ -s
i gallon
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I gallon
68/
7/6
('sent by road)
I pint
16/Carriage: Orders no to 5l- 9d.. up to 10(.
729
each.
0C139, OC I40,
0C204, ORP60, XA70I, XA703,
GET7, GETS, GET9, XC 14
BYI00, 0A21 I.
107- each. 0C19, 0C22, 0C25,
0C26, 0C28, 0C35, 2S013.
NOT
WORKING
TV
SETS
20
35 I_
CONLYRS
OR 20 FOR E25
EACH
PALMERSTONE ROAD
READING, BERKS.
EARLEY
Sr-
Built
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I
MORSE
a
EASYE
The famous RHYTHM RECORDED
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One student. aged 20. took only 13
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Moose easily and naturally please
enclose 8d. in stamps or two international reply coupons for full
explanatory booklet
,
ZENNER DIODES
4.7v. to 30v., kw. 316, 1.5w.
7w. 61- each.
51 -,
-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
Classics and Swing.
Write NOW for free leaflet and further
details to C.
S., 20 Maude Street,
Darlington, Durham. Send 3d. stamp.
r
Plus many more. Send 6d. in
stamps for full list and eq. chart
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78
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Amplifiers, Records Car & Transistor
Radios, Components etc. Send s.a.e.
to EDDY'S (NOttm.) Ltd., 116 Alfreton 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. Wolverhampton.
RADIO
De-Luxe, Pocket Sized model with Sony
transistors, plus Hide Case, Personal
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g
ONLY 22 -19-6 COMPLETE
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INDUSTRIAL SUPPLIES
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WE BUY New Valves,
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A
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SURPLUS HANDBOOKS
19 set Instruction Handbook 3/8
1155 Instruction Handbook 3/6,
p/p 6d.
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,
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December, 1965
PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS
730
SITUATIONS VACANT
SITUATIONS VACANT
SITUATIONS VACANT
(continued)
(continued)
RADIO-A.M.I.E.R.E., City
TV AND
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
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and Electronics write for 156 -page
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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
CENTRAL ELECTRICITY
GENERATING BOARD
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(RADIOMOBILE) LTD.
Goodwood Works
S.
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0171
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Amateur's Licence, R.T.E.B.,
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from BRITISH NATIONAL RADIO
Applications are invited for the following SCHOOL, Russell Street, Reading.
position at Hinkley Point Nuclear Power
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SERVICE SHEETS
Maintenance Craftsman
(Instruments)
ability
Please apply te:
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FULL -TIME TECHNICAL EXPERIrequired for
SALESMAN,
ENCED
Write, giving full
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details of age previous experience
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HENRY'S RADIO LTD., 303 Edgware
A
Applicants should preferably have had
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A knowledge of Conventional Power
Station instrumentation would be an
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The conditions of service will be in
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After two years service
a
further 8s. 6d.
per week is paid.
Applications on Form AE /6M, which may
obtained from the Station Superintendent, Hinkley Point Nuclear Power
Station, near Bridgwater, Somerset, should
be completed and returned by 4th December, 1965, quoting ref. P.W.
be
SERVICE SHEETS for all makes of
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S.A.E. inquiries. Catalogue of 6.000
Valves, modern and
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obsolete. Radio /TV Books. S.A.E.
lists. HAMILTON RADIO, Western
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SERVICE SHEETS, Radio and Television, 41 post paid. VEST AND
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SERVICE SHEETS. Radio, TV, 5,000
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Bank.
11
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SERVICE SHEETS, Radio and TV. by
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SERVICE SHEETS
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RADIO RENTALS
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(Required)
TELEVISION
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& RIGGERS
Clean driving licence essential. Permanent position
with superannuation and sickness benefit scheme.
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Apply by letter or telephone our local branch or
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We have the largest display of Service Sheets for all makes and types
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enclose remittance of
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PRACTICAL WIRELESS CLASSIFIED ADVERTISEMENTS
December, 1965
EDUCATIONAL
PADGETTS
Ist and 2nd Class P.M.G. Certificates and B.O.T. Radar Maintenance Certificate.
Conversion Course (2nd Class to
Ist Class).
R.T. Courses (for Full or Restrict.
Telephone: Cleckheaton
Licensed Aircraft Radio
Engineers
,
full -time
course
for
A.R.M.E. Licences, categories A &
B, and 6 months' courses for
Radar Rating in association with
above.
2-year,
Training given on the latest types of Marine and Aircraft Equipment
in the newly equipped Laboratories at
THE SCHOOL OF MARINE RADIO AND RADAR
write to:
THE REGISTRAR
BRISTOL TECHNICAL COLLEGE
ASHLEY DOWN, BRISTOL 7
RADIO OFFICERS see the world.
and Shore appointments.
Our many recent successes provide
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
Satisfaction or refund of fee "
Thousands of passes
For
seta C s of modern cou -ses in ail
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/+
Post 2/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 rom 12 or
b volts. 101 -, post paid.
Bush (2ln. TV 24 C 13 channel TV. Complete
and tested with good tube. only wants cleaning, 55 / - carriage 10/ -, G.B.
VALVE LIST
when
1/6
2l5/313/2/8
5/4/8
90.
4/-
ELBO
EL84
ECC81
ECC82
EY51
EY86
EBF80
ESN
ECC83
EL38
EFbI
replying,
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20L1
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PY81
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local stamp OK for literature. "GLOBE,
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8/6
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1/6
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6CR8
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ARP12
50
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PCL85
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"PRACTICAL WIRELESS"
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U801
U281
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Few JAP earpieces complete with lead and
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EL91
METAL
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additional trainee vacancies during chassis racks
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Orants available. Day and Lions. PHILPOTTS
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for
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WIRELESS COLLEGE. LTD Chapman St., Loughborough.
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AW43180. 30/ -. MN 43/6, 301 -. MW43/69, 30 /
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101-
I
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Reeialmed Tubes. 51x months' guarantee.
ed Licence).
For details
HALL
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BRISTOL TECHNICAL COLLEGE
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Marine Radio Officers
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RADIO STORE
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I
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Contains lull details of colour codes;
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ve pages. illustrated, over 62 pages of
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lac. 80. FROM ALL BOOKSELLERS
or, in case of difficulty 118.6d. by post from
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NEWNES
PRACTICAL
732
10/14 WATT HI -FI AMPLIFIER KIT
stylish
finished
A
monaural
amplifier
ith
SINGLE PLAYERS
812.10,8, Carr. 5/6
GARRARD SP25 De Luxe
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
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88.8.0
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Super rep-
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Standard GARRARD Autoslim
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GARRARD AT8....810.10.0, Carr. 8/6 on each.
All the above unite are complete with t/o mono
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both
music and
speech
with negligible hum.
Separate inputs for mike and gram, allow records
and announcements to follow each other. Fully
shrouded section wound output transformer to
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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).
P.
19.6'.Á
8/6
All parts sold separately. ONLY
Also available ready built and tested complete with
P.
8/8.
P.
&
standard input sockets. 88.15.0.
Carrying Case for above 28(8, P. & P. 7/6
£6.
SPECIAL HARVERSON OFFER ! ! !
BRAND NEW HEAVY DUTY Lean. SPEAKERS
Response 45 c /a -13 Ke /a ltin. voice coil. Available
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HIGH GAIN 4- TRANSISTOR
in
PRINTED CIRCUIT AMPLIFIER KIT
Typo TAI
THE NEW HARYERSON KIT FOR THE HOME
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ONLY
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dropper
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Heavy duty double -wound mams transformer
Separate Baas, Treble
with electrostatic screen.
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Heavy
negative feedback loop over 2 stages ensures high
output at excellent quality with rely low distorSuitable for use with guitar. microtion factor.
phone or record player.
Provision for remote
All
mounting et controls or direct on chasms.
this builds onto a chassis sire only 7 4-ins wide x 4in.
All components and
deep. Overall height 41ím
Very olear and concise
valves are brand new.
Instructions enable even the inexperienced amaSupplied
teur to construct with 100% eaccess.
complete with valves, output transformer (8 ohms
only), screened lead, wire, nuts, bolts, solder etc.
PRICE
QUALITY
RECORD
top -quality record
79/6
PLAYER
AMPLIFIER
player amplifier.
She
e
A
maker.
Guar-
anteed
non-drift
Per meabili tytuning
Frequency coverage
88 -150
Mc/e
Balanced diode output.
discriminator.
Two I.F. stages and
Attractive maroon and gold
SPECIAL PURCHASE!
FI
MANUFACTURERS
watt OUTPUT TRANSFORMERS to
match pair of ECL88's in push -pull to 3 ohm
output. ONLY 11/ -. P. & P. 2/6.
watt ULTRA LINEAR OUTPUT TRANSFORMERS to match pap of ECL82's in push pull to 3 ohm output. ONLY 15/ -, P. & P. 216.
SPECIAL MAINS TRANSFORMERS to match
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250v. 80mA half wave and 6.3v. 2 save.
ONLY 12/8. P. A P. 2/6.
7-10
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. Absolutely complete.
TRANSISTOR AND DIODE
SUPERHET
first-class
2
waveband transistor superhet
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
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
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Bet of Mollard 8 translators 0044, 2-0045 OC81D
matched pair 0081 26/ -, ORP12 Cadmium Sulphide
dial (7 x 3in. glu).
Self- powered using a good
quality mains transformer and valve rectifier.
Valves used: ECC85, two EF80's and EZ80
Fully drilled chassie.
Sire of com(rectifier).
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 instructions 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. &
Sloe approx. 9} x 61 x 3 9in. Suitable for above
using 3 }In. speaker. 25 / -. P. A P. 2/6.
SPECIAL PURCHASE TURRET TUNERS
By famous maker. Brand new and unused. Complete
170 HIGH ST., MERTON, S.W.19
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).
FROM LEADING
HI
7-10
CABINET
Printed circuit panel (size 85 x 2/ in.).
3 prealigned IF transformers. High -gain Ferrite Rod
Aerial.
All First -grade transistors.
Car aerial
All parts supwinding.
Push-pull output.
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).
famous
1
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
F.M.
head by
el /PLAYER
for
filaments
if required. 2/6 extra.
P.Aé/-
double -wound mains transformer, ECC83, BLS4,
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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
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QUALITY PORTABLE
x
high
overall.
Tan. w. s 21-1n. d. z 5 }fm h. This amplifier (was
used In a 28 gn. record player) employs heavy duty
tuning
wldes-2in
3 }In
ELS4, EZ80
VALVES
Special features ine-
A
I
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.
8 VALVE 4 WATT
USING ECC88
ago extras to Dn
HARVERSON'S F.M. TUNER Mk.
ance. 200 /230
v.
shaded pole motor
with 90 v. tap for
valve heaters. High
gain crystal pickup with turnover
LP /78 head complete with sapphire etylii.
deep
all
Comprehensive circuit diagram, practical layout
and parts list 2 /S. (Free with kite).
Peak output in excess of 1} watts.
All standard
Built on printed circuit
British components.
Generous she Driver and Outpanel size e x SinOutput transformer tapped for
put Transformera
Transistors (OET114)
3 ohm and 15 ohm speakers.
or Bl Mollard OC81D and matched pale of 0(81 o/pa
Everything supplied, wire,
9 volt operation.
Comprehensive easy
battery clips, solder etc.
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.
69/6 grf
ONLY
lin. metallturntable
Low flutter perform-
really excellent
purpose A.C.
mains 200 /240v.
AMPLIFIER
KIT
TYPE HSL `FOUR'
A
1965
LATEST MODEL B.S.R. TU;I2
4 -SPEED PLAYER
AND PICK -UP
4-SPEED PLAYER UNIT BARGAINS
All Brand New in Maker's Original Packing
B.B.R. G07 with unit mounted pick -up arm.
an
output of
14
watts
of
December,
WIRELESS
COIL AND TRANSFORMER SET
FOR TRANSISTOR SUPERHET
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.
3
Cell 10/8.
EDIBWAN MAZDA
PXA101 6 /6; XA103 6/6.
R.F.I. Pack: 1- PXA102 Mixer; 2-PXA 101
10/6
I.F. Amp. (Equiv.0044 and 0045)
PXA102 Osc.:
PXA101 I.F.
R.F. 2 Pack;
12/8
1- PXA102 Mixer
Matched
L.F.6 Pack: Consisting of PXB113 Driver
pair P1171 mounted complete with heat sinks
12/6
(Equiv. OC81D and OCR)
ALL TRANSISTORS POST FREE.
2-
1-
HARVERSON SURPLUS CO. LTD.
CHErrywood
Early closing Wed. I p.m.
A
Open all day Saturday
few minutes ¡rom South Wimbledon Tube Station
3985
(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
www.americanradiohistory.com
BEE
RIGHT
HAND
PAGE
FOR
MORE
ITEMS
y
Dec ember,
PRACTICAL
1965
AMPLIFIERS
-VALVE AUDIO AMPLIFIER
MODEL HA34
SPEAKERS
NORTHCOURT "FIVE" AMPLIFIER
3
ueaiguod i
lit -Pi
..e'produrtiou
oi
A.C. Maint
operation.
Ready
on
plated
burn
heavy gauge metal
tine
chassis
741u.
w. x 4in. d. a 411u. h.
Incorporate. EtiC83
11I.84, ELBU valves.
Heavy duty (ionisewound 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 controls The HA34 has been 'morally designed for us
and our quantity order enablesa4us pto utter them
complete with knobs. valves.
P. A P.
etc. wired and tested MI only RA
u
..
/0; I/fin.
3
a/" .. n
OHM SPEAKERS
Nin 21 / -; IOin., 25/ -:
15 / -t
15 ohm, 30/ -1, 10in. x gin.. 26/ -.
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.
12
27/6; 112in.
121n.,
E,M.I.
1311
x
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/ -.
output amplifier
incorporates
separate volume,
treble and
controls.
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 photographic 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,
size
Inc. tterminal.uWhite 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 CABINET 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.
socket inputs
are fitted. Twin
speakers
1
give
exceptionally
realistic reproduction 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.
P.A.
EQUIPMENT CABINETS
DISTINCTION
OF
EXTENSION SPEAKER
Suitable for radio
and record players. Size: Length
10in. Height Tin.
Depth Sin.Fitted
in durable industrial
finished
wood
cabinet,
attractively fin-
Imperial
grey.
Speaker
front covered in Vynair. Price 29/9 Retail.
As above fitted with volume control. 35/9
Retail.
P.A.
,
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
,
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,
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.
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
TRANSFORMERS
UPRIGHT
350-0 -350 100mA 6.3v. 4A C.T. 0-5v. at
3
300-0 -300 IOOmA 6.3v. 4A C.T. 0.5v. at
3
amp. 29/6 Retail.
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,
v¿
PUDSEY, Yorks.
Designed
NEW LEWIS
RADIO CATALOGUE
THE
to
ansiar
cour
011010e
u:
Cabinet.
The New Lewis Radio Cabinet Catalogue -the most comprehensive ever
prepared. Sent absolutely FRRRI
Please send your PitRE 24 puoi cabinet
catalogue.
N.S. KITS
-
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).
No Soldering
NAME
ADDRESS
(Dept. 125)
Capitals please
G. A. TAYLOR LTD.
21
1 Harverson Surplus Co. Ltd.
Illustrated in this advertisement are
TWIN EXTENSION SPEAKER
t
T.C.C. SUPPRESSOR CONDENSERS. 250v. A.C.
.005
.005 z .1. to tubular can fm. long r
fin. die. '2 for 3 / -, poet tree.
TRANSISTOR DRIVER and 0/P TRANSFORM(Tapped 3 ohm and
ohm
R 4 suitable Translators giving approx. 11 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
plug. Suitable for F.M. or TV 12/6. P. A P. 2/
bass
Two jack
ished in mottled
TAPE DECK
8.SR. MONARDECK.
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIillll
Suitable for guitars, grams and
radios.The 5 watt
a
records
BRAND NEW
733
WIRELESS
HYDE ROAD, DENTON
MANCHESTER
www.americanradiohistory.com
s
L
100 Chase Side. Southgate, London
lei Palmers Green 3733/9666
N.14.
e
December,
PRACTICAL WIRELESS
734
1965
MEnts
MORE PRACTICAL
HOUSEHOLDER
SPECIAL
KNOW -HOW FOR
ea
+
EEE
THIS ISSUE
tEaca£s Ist )àa
fL
8t7f8
ü?ats &fa ïs h*ee i[.){3
Ft (!shB8i8t Wafer Egcg
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
....
ilEttii
tr a
PRACTICAL WIRELESS.
riTel
1
PRACTICAL
HOUSEHOLDER
Britain's first and foremost
magazine,
do-it-yourself
covering 101 jobs about the
home. Monthly 1/6.
PRACTICAL
MOTORIST
PRACTICAL
MOTORIST
F
E
'+
`
guide in
Winter
Motoring
Shows motorists how to do
their own repairs, maintenance and overhaul, and save
pounds on garage costs.
MONTHLY 2/
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
735
WIRELESS
RADIO CLEARANCE LTD.
TEST METERS
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.
/mired.
w.
to
inrlw New
7000
7000
7000
7000
8600
7000
7000
6500
6000
7000
21
2f
2f
3
38
31
5
5
s
5
6
8
ö
x
x
x
x
x
x
x
9000
7000
9000
9600
8500
9600
9500
3
3
3
3
4
4
4
Site
Gauss
in.
in.
inches lined
Maw Pries
35
60
80
9/6
8/8
6
19/-
38 7000
38 9600
31 9500
4 9500
9500
4
4 10000
4 12000
9
3
8
10 /8
3
11
4
35
0
10/9/6
86
12 /-
3
3
3
8
3
36
4
4
9/8
3
16
8/8/8
9
10 /121-
7
7
7
x
7
7
7
x
x
7
x
x
x
x
.isms Pried
3
10/8
35
4
incises frees
4
9500
5
7000
5
7500
9500
5
9500
5
8500
68
7000
10/6
19 /8
11/9/0
11/8
11 /6
50
35
35
5
60
36
15
Gauss
/raped.
ohms Price
25
11 /6
3
15
26
8/8
9/10/8
12/8
10/8
3
11/-
12 /21 6000
3
5
3
3
9/6
9/10/22/6
10 x 8
10 x 6
6
U/8
25
23/8
3
/-
12/8
12/6
16/6
3
3
x
x 21 7000
x 2J 9500
10 x 6 11000
9/8
110
80
plMdytitn
8
8
11000
11000
krif
eters
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.
Little Newport Street, London, W.C.2
(adjoining Lisle Street)
o
LISTEN
J
è
4.1
WORLD'S RADIO AMATEUR
3, AND BROADCAST STATIONS WITH
THE GREATEST OF EASE
1!!
G
2
We HAVE SOLVED your aerial problem for
WORLD -WIDE RECEPTION -NO MATTER
WdERE YOU LIVE ! ! !
World Expert Radio Amateur WIBB
(U.S.A.) claims the
"JOYSTICK"
aerial- easier to read stations than with
his massive 520' YEE aerial 70' high.
ZL4GA, who is probably NEW ZEALAND'S best known Radio Amateur,
has scrapped his outstanding 300' 45'
high aerial and has WORKED ALL
CONTINENTS on the JOYSTICK in
under 12 hours ! I !
"CQ" the Rodio Amateur's journal
OYSTICK better for recepclaims
tion than the world popular DIPOLE
(four different receivers used to confirm
this decision).
(Standard system), 17.7.6 (De -luxe system)
including carriage and packing.
Money Back if not Delighted
£2
*
On your OWN TRANSISTOR PORTABLE!
Plugs -No Connections' Just. place Dewtron
Wave Trap near radio!
Boosts 'Pirate' and
No
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
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 VOLTMETERS. 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
x 38in. high. 95.6.0. JASA 6 watts, ize
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"
7
YOU CAN BE THE PROUD OWNER OF THE
WORLD'S MOST VERSATILE 8 COMPACT
"JOYSTICK" COMPLETE RECEIVING SYSTEM
FOR AS LITTLE AS
system), 66.6.0
15.5.0 (DX- MAGNET
POST FREE
.
40
AND ENJOY THE
À
-
J
on.
7000
9500
6000
7000
7500
9000
9500
9500
si
8/-
Size
imps
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
Amplifiers
tecell
R3/2D-D3-2-1-Y, 2/each
ready to switch
aRecorder
79/8:
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 / -.
12
t
ow
a,
Gauss
convinced? Then send for
brochure and showers of testimonials
Not
to:-
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
30
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
LONDON,
PARTRIDGE ELECTRONICS LTD
(Dept. P.W.)
CAISTER HOUSE, PROSPECT ROAD
BROADSTAIRS, KENT
I.R.C. Exhibition Stand No. 26
www.americanradiohistory.com
Telephone:
TL-
ROAD,
W,C.1
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 Holborn (Chancery Lane Station) and 5 mint. by bus
from King's Cross.
PRACTICAL
736
44A WESTBOURNE GROVE
6//- 6AH6
BAJS
BAKS
11/8/8/8/5/-
OA3
OB2
OB3
003
0133
6AK6
CART
6AL5
CARO
1A60T/05%- 6AN4
1A70T 8/- 6A1N5
1AD4 10/- 6AN8
1B30T
1U50T
7/- 6AQ4
8/- 6AQ5
1D5
7/8 6AQ6A
7/- 6AR5
7/- 6AR6
1060T
1H50T
1L4
1L8
10/9/6/8
7/-
1V
1v2
1R2A
1122
8/6/8/6/10/7/-
8/-
6AV8
e/IiAW9A 14/-
BA14GT1
6A116t1
8/-
12/8
7/- 8137
5/6/- 6138
7/2A40 80/- 6B80
2/6
2026A 5/- BBeOT 5/2061
18/- 6BA6
5/2C52
12/- BBA7 16/2063
50/- 61304 17/6
20W4 18/- 613E6
5/8
21321
e/- 613060 15/2E22 25/- BRFB
6/2224 40/- BBHS 7/8
2E26 80/- BRJB
8/2021 12/- (IRJ7
7/212
8/- 613114 85/82.a
4/- BBK7A 9/32.6
7/- 8BL7OT 9/3117
6/- 6BN6
7/8
22
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807
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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.
dla tseree7
P.
/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 /- eSmall quantity available of second hand anentbites, °hacked, in perfect order .-, 8/9 sa,
F. A P. S/S Per eel.
PHOTCEL
O
0813
Camel=
am 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
-,
,.
Packing and postage 9d.
12/6
PRACTICAL
December, 1965
PRACTICAL
WIRELESS
iii
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
Plow
The Strand Amplifier ..
The PW Signal Generator
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:::}
sr-
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The Tutor
51-
The Citizen
...f
5 1-
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}
7,6
The PW 35 -watt Guitar Amplifier
61-
The Mini -amp
sr-
The PT Multimeter
The Berkeley Loudspeaker Enclosure (
...
The Luxembourg Tuner
The PW Troubadour ...
...
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The PW Britannic Two
The PW Mercury Six ...
:::}
Beginner's Short Wave Two ...
...
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:::}
Beginner's 10 -watt Transmitter
Transmitting and Aerial Data...
:::}
PW "Sixteen" Multirange Meter
.._}
Test Meter Applications Chart
The Celeste 7- transistor Portable Radio
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Transistor Radio Mains Unit ...
...
7 Mas Transceiver
...}
}
...
...
The Autocrat Car Radio
sr-
The Beginner's Short Wave Superhet
51-
The Empire
5f-
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
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(a) We cannot undertake to design equipment or
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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
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MW LW POCKET SUPERHET RADIO
TO BUILD
**
-
¿_
-
`
Easy
Full MED and long waves.
5 x 3 x I }in.
P.P. 21- (Battery 2'6, Phone 51 -)
Amazing sensitivity and
selectivity.
85/-
NEW
*SHORT
i
The only FULLY tunable 3Waveband Radio available to
Constructor
Home
the
I
watt output.
Printed circuit.
Car aerial
tuner.
Geared
socket with special circuits.
Push-button unit. 6- transistor
high gain superhet design.
I
.
£0196
.
Size
x
11
Case
in.
31
71 x
fabric covered with chromed
front and fittings. All parts
P.P.
sold separately and TOTAL COST
316.
TO BUILD
fully guaranteed
Waveband
Two
advertised.
previously
as
'CONVAIR"
Portable to Build, still available. Total Cost £7.19.6. P.P. 2'6.
P.P. 316.
factory built assemblies -lust interconnect,
** Supplied
-pall design.
transistor
-full tuning range.
** button wavechange
car-chromed front dial.
in. -fits
superhet circuit
*** Full
Units available separately.
Guaranteed high performance and quality.
as
push
6PushSize 7 x 4 x 2
"GLOBEMASTER"
!
WAVES
MEDIUM AND
LONG WAVES
*
1
TWO WAVEBAND ALL TRANSISTOR'
CAR RADIO TO ASSEMBLE
TOTAL COST
TO BUILD
*
*
output.
printed circuit.
Slow geared tuning.
Push-pull speaker
* Moulded cabinet
TOTAL COST
TO BUILD
PROVED and TESTED DESIGNS
FULL AFTER SALES SERVICE AND GUARANTEE
UNBEATABLE FOR PERFORMANCE AND VALUE
DETAILED LEAFLETS FREE ON REQUEST
6- transistor plus diode.
*
*
*
December, 1965
WIRELESS
PRACTICAL
iv
£8.19.6
*
any
WATT AND
IO
I
20
I
Prebuilt
Collaro
-
-6
valves
equipment
studio decks-portable
-8
x
Cabinet with
output.
MSNiYBIYfse
£26
*Cabinet
Four Track deck £13.19.6. P.P. 5' -. Amplifier
and speaker 5 gns. P.P. 316.
11
£30
or SPECIAL PRICE
#
P.P. 816
gns. P.P. 316.
12
Redesigns.
spouse 40 c;s
kc:s.
20
to
100 mV sensi-
tivity.
Unit
FOUR TRACK
I.
For
1215 ohm
speakers, 40 volt supply. PRICE
VHF FM TUNER TO BUILD
4- diodes.
1
volt.
to ohms.
Unit
* transistors,
BUILT
circuit superhet.
* Printed range
Stereo
(Mains units Mono
Mc's.
to
* Tuning
*
PREAMPLIFIERS -MONO AND
double tuned
*
inputs, I} mV to
2. For 3
j6
87
IFT'S
-9
volt
mA oper-
9
ated.
All parts sold separately.
*
* Output to volt.
2}
*
(complete with front
extra.
Cabinet Assembly
*panel)
up
Size 4 x 34 x
P.P. 216
TOTAL COST£6.19.6
TO BUILD
.-d
c
\/
*
I
BUILT
201-
I; WATT
PACKAGE AMPLIFIERS
push -pull
circuit designs.
Peak output 10 watt and
6- transistor
Size only 2} x 2 x
5
watt,
18
Output for
7 mV into
WATT
65/_
11
9
1
12
P.P6
5
volt.
79/6
WATT
-
built with Front Panel,
SlltflfA
I
10 '1p
BUILT
316.
3
panel 1216).
VHF FM TUNER TO ASSEMBLE
prebuilt
* Supplied
aligned units
work just interconnect.
** to to Kohmtuning.
* output.
transistor printed circuit.
*(AllSuperhet
units available separately).
as
plus
and
metal
108 Mc s. FM
100
100 mV
88
6-
design.
HENRY'S RADIO LTD.
open Mon. to Sat. 9 -6
303 EDGWARE RD., LONDON W2
a
VGIUMF
function preamplifier.
P.P.
Size 9} x 2f x 2in.
BUILT £5.10.0 21(Brown: Gold front panel. 816).
651 -. P.P. 116.
Unit 4. Simplified version of Unit 3. Price built
amplifiers.
Unit 5. Stereo preamp Idler for use with two power
Gold
PRICE
Size 9 x 31
7' 6 P.P. (Brown
P.1P.
FM
Send
-FILttP
Unit
PRICE
7916, P.P.216.
PADdmgton 1008 9
Let us quote for
--
IP BII - -BASS
use
POCKET RECEIVER KIT £5. 19. 6.
built,
SINCLAIR. Micro -6, 59'6; X10 Kit. £5.19.6; X100.19.6.
£6.19.6; X20 Kit, £7.19.6; X20 built,
NEW
VERSIONS.
of
Mono full
3.
STEREO
-
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.
to 5 ohm speakers.
Kohm. 30 c,s to 16 kc's.
3
Unit
-
P.P.
216
LOW
watt.
3
in.
range
Complete
controls.
x lá in.
printed
volt; I} watt,
I
with If or 5 watt Amplifiers.
inputs, separate treble vol. bass controls. Price
NEW PREAMPLIFIER for
switched
in.
WATT AND
S
*
**
*
I
-
8
K to
300 m V at
500 Kohm. Response
kc's
20
30 es to
-- - -
6916)
5916
105
RF stage and
2,6
£5.10.0
4
5
P.P.
£3. 9.6
BUILT
5-
6
20
peak.
watts
6- transistor
10
or SPECIAL PRICE
P.P. 816 TWO TRACK
\s
watts RMS
power
music
°
gns. P.P. 51 -.
P.P. 316.
speaker, 5 gns. P.P. 3'b.
i I
I
and 2
I
10
5
*Amplifier
Two track deck
gns.
Units
AMPLIFIERS
in. speakers.
Complete recording and playback.
cabinets
WATT AMPLIFIERS
PRE -BUILT
ALL TRANSISTOR
TWO AND FOUR TRACK PORTABLE AND
TESTED UNITS
TAPE RECORDERS TO ASSEMBLE
Thurs.
1
p.m.
Open all day Saturday
Parts for your circuit.
list for quick reply.
r
Size 94 x 34 x 4 in.
TOTAL COST
TO BUILD
COMPONENT
12.1
7.6
P.P. 216
CATALOGUE
Fully detailed and
illustrated
pages. All
catalogue. Now 96
types of components and
at competitive
prices. Price 216 post paid.
equipment
www.americanradiohistory.com
NEW 12 Page
CATALOGUE, S00 Transistors and Devices, Heat
Sinks, 1000 Crystals, 800
Valves, etc., etc. Lower
Prices. More Types. Ask
for Your FREE Copy.
FREE
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