Collins 830B 1A 250 Watt FM Broadcast Transmitter Manual ..

User Manual: Pdf Collins 830B-1A 250 ..

Open the PDF directly: View PDF .
Page Count: 127

Download
Open PDF In Browser	View PDF

Collins Radio Company

I Dallas,

STEAM POWERED RADIO.COM

Texas

t .

GUARANTEE
The equipment described herein is sold under the following guarantee:
Collins agrees to repair or replace, without charge, any equipm1rnt, parts, or accessories which are defective as to design, workmanship or material, and which are returned to Collins at its factory, transportation
~ _,; ..

prepaid, provided

(a) Notice of the claimed defect is given Collins within two ~)+Year from date of delivery and goods
\ ·are returned in accordance with Collins' instructions.
(b) Equipment, accessories, tubes, and batteries not manufactured by Collins or from Collins' designs

are subject to only such adjustments as Collins may obtain from the supplier thereof.
(c) No equipment or accessory shall be deemed to be defective if, due to exposure or excessive moisture
in the atmosphere or otherwise after delivery, it shall fail to operate ina normal or proper manner.
Collins further guarantees that any radio transmitter described herein will deliver full radio frequency
power output at the antenna lead when connected to a suitable load, but such guarantee shall not be construed
as a guarantee of any definite coverage or range of said apparatus.
The guarantee of these paragraphs is void if equipment is altered or repaired by others than Collins or
its authorized service center.
No other warranties, expressed or implied, shall be applicable to any equipment sold hereunder, and the
foregoing shall .constitute the Buyer's sole right and remedy under the agreements in this paragraph contained. In no event shall Collins have any liability for consequential damages, or for loss, damage or expense
directly or indirectly arising from the use of the products, or any inability to use them either separately or
in combination with other equipment or materials, or from any other cause.

HOW TO RETURN MATERIAL OR EQUIPMENT.

If, for any reason, you should wish to return

material or equipment, whether under the
including the details listed below, insofar
particulars
full
giving
us,
notify
should
you
otherwise,
or
guarantee
as applicable. If the item is thought to be defective, such notice must give full information as to nature of
defect and identification (including part number if possible) of part considered defective. (With respect to
tubes we suggest that your adjustments can be speeded up if you give notice of defect directly to the tube
manufacturer.) Upon receipt of such notice, Collins will promptly advise you respecting the return. Failure
to secure our 9 dvice prior to the forwarding of the goods or failure to provide full particulars may cause
unnecessary delay in handling of your returned merchandise.
ADDRESS:
Collins Radio Company
Service Parts Deparrrnen t
Dallas, Texas 75 207

INFORMATION NEEDED:
Type number, name, and serial number of equipment
Date of delivery of equipment
Date placed in service
Number of hours of service
Nature of trouble
Cause of trouble if known
Part number (9 or 10 digit number) and name of part
thought to be causing trouble
(H) Item or symbol number of same obtained from parts
list or schematic
(I) Collins' number (and name) of unit sub-assemblies
involved in trouble
(J) Remarks

(A)
(B)
(C)
(D)
(E)
(F)
(G)

HOW TO ORDER REPLACEMENT PARTS.

When ordering replacement parts, you should direct your order as indicated below and furnish the
give you better replacement service, please be
to
us
enable
To
applicable.
following information insofar as
sure to give us complete information.
ADDRESS:
Collins Radio Company
Service Parts Department
Dallas, Texas 75207

STEAM POWERED RADIO.COM

INFORMATION NEEDED:
(A) Quantity required
(B) Collins' part number (9 or 10 digit number) and description
(C) Item or symbol number obtained from parts list or
schematic
(D) Collins' type number, name, and serial number of
principal equipment
(E) Unit sub-assembly number (where applicable)

523-0166000-002 43A

2nd Edition, 1 January 1967

•

.••

~

COLLINS

~
instruction hook

830B-IA
250-Watt FM Broadcast Transmitter

-

This manual includes:
SP -183 830B-1A 250-Wott FM Broadcast Transmitter
523-0755439
TD-536 A830-2 10-Wott Wide-Bond FM Broadcast Exciter 523-0755303
TD-53 7 786M-1 Stereo Gen erotor (optional)
523-0755304
52:3 -0755596
TD-538 B830-1 250-Wott FM Power Amplifier
~

Co llins Radi o Company 1962, 1967

~-.
Collins Radio Company

I Dallas,

Texas

P r inted in U.S. A .

STEAM POWERED RADIO.COM

---_,_

830B--1A 250-Watt"°FM. Broadcast Transmitter

523-0755439-002439

STEAM POWERED RADIO.COM

System fustructions

SP-183
523-0755439-002439
2nd Edition, 1 January 1967

~

COLJ_,INS

~
system instructions

830B-1A
250-Watt FM Broadcast Transmitter
CJ Collins R adio Company 1962, 1967

Collins Radio Company

I Dallas,

Texas

Pri n ted i n U. S. A.

STEAM POWERED RADIO.COM

,,/

I
table of contents
Page

Section
1

GENERAL DESCRIPTION .

1-1

1. 1

1- 1
1-1
1-1
1- 1
1-1
1-1
1-1
1-2
1-2
1-2

1. 2
1. 3

1. 3. 1
1. 3. 2
1. 4
1. 5
1. 6

1. 6. 1
1. 6. 2

2

INSTALLATION .
2. 1
2.2

2. 3
2.4
2. 5
2. 6
2. 7
3

General
Starting the Transmitter in Normal Operation

2-1
2-1
2-1
2-1
2- 1

2- 2
2-2
2- 2
3-1/ 3-2

3-1/ 3-2
3-1/ 3-2

PRINCIPLES OF OPERATION

4-1

4.

4-1
4-1
4-1
4-2
4-2
4-2

1

4. 2
4.3
4.4
4.5

4.6

5

Unpacking and Inspecting
Transmitter Location
External Connections
Internal Connections
Remote Control
Frequency Change .
Starting the Transmitter in a New Installation.

OPERATION.
3. 1
3. 2

4

Purpose of Instruction Book
Purpose of Equipment .
Description of Equipment .
Physical Description .
Electrical Description .
Equipment Supplied
Accessory Equipment .
Equipment Specifications
Mechanical
Electrical

General .
A830-2 10 W Wide-Band FM Broadcast Exciter
B830- l 250- Watt FM Power Amplifier
Harmonic Filter
Control Circuits
Plate Contactor and Plate Power Supply

MAINTENANCE .

5. 1
5. 2
5. 3
5.4

5.5
5.6
5. 7
5.8

STEAM POWERED RADIO.COM

General .
Normal Tuning Procedures
Modulator and AFC Discriminator Adjustment Procedures
Distortion Testing Procedure
Audio Frequency Response Measurements .
FM Noise Measurement
AM Noise Measurements
Trouble Shooting

5-1
5-1
5-1
5-2
5-2
5-5

5-6
5- 6
5-6

list of illustrations
Figure
1- 1
2- 1
2- 2
2-3
2- 4
4- 1
5- 1
5- 2
5-3
5-4

5-5

/
Overall View, 830B- 1A 250-Watt FM Broadcast Transmitter (B502- 187- Pb)
Outline and Installation Diagram, 830B- lA 250- Watt FM Broadcast
Transmitter (C848-02-5).
Transformer Details (C848- 15- 3) .
Wired Remote Control Panel (B502- 192- 4)
Plate Cavity Tuning Chart (C848-12-X)
Block Diagram, 830B-1A 250- Watt FM Broadcast Transmitter (C848-22-5).
Distortion Test Setup (C848- 18-3) .
Audio Frequency Response Test Setup (C848- 19 - 3)
Audio Frequency Response L imits (C847- 04- X)
FM Noise Test Setup (C848- 20- 3)
AM Noise Test Setup (C848-21-3)

Page
1-0
2-3/ 2- 4

2-5
.
2- 6
. 2- 9/ 2- 10
4-3/ 4-4
5- 5

5-6
5- 7
5-8
5-8

list of tables
Table
1-1
1- 2
1-3
2- 1
5- 1
5-2
5-3

Page
Unit Instructions.
~quipment Supplied .
Accessory Equipment
Crystal Part Numbers
Abbreviated Tuning Procedures
Distor tion Checks
Normal Transmitter Meter Indications

ii
STEAM POWERED RADIO.COM

1- 1

1- 2
1-2

2-7
5-3/ 5-4

5- 5
. 5-9/ 5-10

general description

C,

Q

L

!... I

...

S

. - - -- - .

Figure 1- 1.
1-0
STEAM POWERED RADIO.COM

(

Overall View, 830B-1A 250-Watt FM Broadcast Transmitter

section

1

general description
1.1

PURPOSE OF INSTRUCTION BOOK.

This instruction book is a guide for installing, adjusting, operating, and maintaining 830B-1A 250-Watt FM
Broadcast Transmitter.
1.2

PURPOSE OF EQUIPMENT.

The 830B-1A 250-Watt FM Broadcast Transmitter is
used for continuous monophonic or optional stereophonic FM broadcast service on a single frequency in
the range from 88 to 108 megahertz with an output
power of 250 watts.
1.3
1.3.1

DESCRIPTION OF EQUIPMENT.
PHYSICAL DESCRIPTION.

The 830B-1A 250-Watt FM Broadcast Transmitter,
shown in figure 1-1, is contained in a single cabinet
that is 38 inches wide, 76 inches high, 27 inches deep,
and weighs approximately 638 pounds. All transmitter
operating controls are l ocated behind the doors on the
front of the cabinet. The filament and plate on-off
controls and four monitoring meters are located at the
top front of the cabinet. The meters may be observed
easily while operating the tuning controls. The transmitter uses eight tubes and 20 transistors, all of which
are accessible from the front of the transmitter. The
bottom front of the transmitter cabinet is removable
to allow access to components on the bottom of the
inside panel.
Large doors at the upper rear of the cabinet allow
access to the upper part of the transmitter for servicing and maintenance. The lower rear half of the
transmitter cabinet is covered by a removable panel
that contains a ventilating fan and a permanent-type
air filter. Operating personnel are protected by both
electrical and mechanical interlocks on the rear doors
and panel. These interlocks ground the transmitter
high-voltage circuits when the doors are opened or
the panel is removed. The power amplifier platetuning cavity is located in an interlocked compartment
at the front of the transmitter.

connected to the transmitter output is suspended from
the top of the cabinet.
Cooling air for the transmitter is drawn through a
permanent-type air filter at the rear of the cabinet
by a low-speed, high-volume fan, and exhausted through
a shielded opening in the top of the cabinet. An
individual pressure blower supplies cooling air directly
to the power amplifier tube.
1.3.2

ELECTRICAL DESCRIPTION.

The 830B-1A 250-Watt FM Broadcast Transmitter is
composed of two electrically-connected subunits: (1) a
wide-band exciter that furnishes a 10-watt FM output
to drive (2) a 250-watt power amplifier. Unit instructions covering the exciter and power amplifier used
in the transmitter are listed in table 1-1. They are
supplied following section V of this system instruction book. The unit instructions contain detailed
descriptions of the two transmitter units.
1.4

EQUIPMENT SUPPLIED.

Table 1-2 lists equipment that is supplied as part of
830B-1A 250-Watt FM Broadcast Transmitter.
1.5

ACCESSORY EQUIPMENT.

Table 1-3 lists accessory equipment that is available for use with 830B-1A 250-Watt FM Broadcast
Transmitter. Information on 786M-1 Stereo Generator is contained in Unit Instructions TD-537 (CPN
523-0755304).

TABLE 1-1.

UNIT INSTRUCTIONS

PUBLICATION

A830-2 10 W Wide-Band
FM Broadcast Exciter

PART
NUMBER

TD-536
523-0755303

Inside the transmitter, heavy iron- core components
are at the bottom of the cabinet. The exciter portion

B830- l 250- Watt FM

of the transmitter is mounted on a 19-inch rack on

Power Amplifier

TD- 538

523-0755596

one side of the cabinet. A harmonic filter that is
1-1
STEAM POWERED RADIO.COM

general description

TABLE 1-2.

EQUIPMENT SUPPLIED

EQUIPMENT

COLLINS
PART NUMBER

A830-2 10 W Wide Band
FM Broadcast Exciter

522-2714-000

B830-l 250-Watt FM
Power Amplifier

549-2008-000

250-Watt/lKw Harmonic
Filter

549-2010-000

TABLE 1-3.

ACCESSORY EQUIPMENT

EQUIPMENT

COLLINS PART NO.

786M-l Stereo Generator

522-2914-000

1.6

Frequency Range:
88 to 108 MHz
Exact operating frequency determined by frequency of crystal in heterodyning oscillator.
Excitation Source:
Crystal-controlled high-stability oscillator using
plated, nontemperature-controlled crystal, controlling an LC modulation oscillator to provide
automatic frequency control. The modulation
oscillator is then heterodyned up to the station
operating frequency by a second high-stability
crystal-controlled oscillator.
Carrier-Frequency Stability:
(
Within ±1000 Hz of specified carrter frequency
over ambient temperature range from +10°C
(55°F) to +55°C (131°F) and line-voltage variations of ±15 percent.
Harmonic and Spurious Radiation:
Any emission appearing on a frequency removed
from the carrier by between 120 kHz and
240 kHz inclusive, is at least 30 db below the
level of the unmodulated carrier.

EQUIPMENT SPECIFICATIONS.

1.6.1

MECHANICAL.

Weight:
638 pounds (approximate)
Size:
38 inches wide, 76 inches high, 27 inches deep
Ventilation:
One ventilating fan, one blower

Any emission appearing on a frequency removed
from the carrier by between 240 kHz and
600 kHz inclusive is at least 40 db below the
level of the unmodulated carrier.
Any emission appearing on a frequency removed
from the carrier by more than 600 kHz is at
least 67 db below the level of the unmodulated
carrier.

Ambient Temperature Range:
+10°C (50°F) to +55°C (131°F)

Modulation Characteristics:
Wide-band direct FM modulation
Standard audio pre-emphasis is incorporated
in modulator.

Ambient Humidity Range:
Up to 95 percent relative humidity

Audio Input Impedance:
600 ohms, balanced

Altitude:
Up to 6000 feet

Audio Input Level:
+10 dbm ±2 db

Shock and Vibration:
Normal handling and transportation

Audio Frequency Response:
Complies with standard FCC 75-microsecond
pre-emphasis curve.

1.6.2

ELECTRICAL.

Power Source:
200 to 250 volts, 60-hertz, single-phase
Maximum Power Requirements:
900 watts
Power Output:
250 watts
Output Impedance:
50 ohms, unbalanced
Maximum swr 2:1
1-2
STEAM POWERED RADIO.COM

Audio Frequency Distortion:
50 to 100 Hz, 1.5 percent maximum
100 to 7500 Hz, 1.0 percent maximum
7500 to 15,000 Hz, 1.5 percent maximum
FM Noise Level:
Not less than 6 5 db below 100 per cent modulation
(±75 kHz)
AM Noise Level (rms):
Not less than 55 db below equivalent 100 percent AM.

section

2

installation
2. 1

UNPACKING AND INSPECTING.

Be careful when uncrating the transmitter and components to avoid damaging the equipment. Inspect the
transmitter carefully for scratches, dents, or other
physical damage. Check for loose screws and bolts.
Inspect all controls, such as switches, for proper
operation as far as can be determined without applying
power to the transmitter. Examine cabl es and wiring,
making sure that all connections are tight and clear of
each other and the chassis. File any damage claims
promptly with the transportation company. If such
claims are to be filed, retain all packing material.

a. Connect the audio input to the transmitter. Bring
the audio signal through the bottom of the cabinet on a
shielded twisted pair. Connect the two audio leads to
terminals 1 and 2 of TB305. If the optional stereophonic operation is employed, the left audio leads are
connected to TB305-1 and 2 and the right audio leads
to TB305-4 and 5. TB305 is located about half way up
the cabinet on the left side as viewedfrom the rear of
the cabinet. Connect the shields to terminal 3 of TB305.
b. Connect the FM monitor to the monitor output
on the top of the cabinet. Refer to figure 2-1. Use type
RG- 58U coaxial cable to make this connection.

Note

Before installation check all transistors
for proper placement. The transistor location tab must be pointing to the transistor socket locating mark placed adjacent
to the transistor socket.
2. 2

TRANSMITTER LOCATION.

Plan transmitter and wiring placement carefully before
starting installation work. Refer to figure 2- 1, the
transmitter installation diagram. This diagram shows
the location of all wiring openings in the transmitter
cabinet. As will be noted, several alternate wiring
arrangements can be used. Select the combination that
best meets the station requirements.

!

Allow adequate clearance both in front and back of the
transmitter. There should be a minimum clearance of
3- 1/2 feet beh ind the transmitter to provide sufficient
room for se r vice work.
2. 3

Before making the antenna connection, be
sure that the transmission line and antenna
present a nominal impedance of 50 ohms
and an swr of not more than 2: 1 at the
transmitter operating frequency. If the
transmitter output is improperly matched,
the transmitter will not operate properly
and maybe damaged. THIS IS IMPORTANT.

EXTERNAL CONNECTIONS.

Refer to figure 2-1 for assistance in making the
following external connections.

WAR'.\I'.\G

I

Disconnect the transmitter 230- volt ac
power from the fused cut- out box before
making any connections to or within the
transmitter.

c. Connect the antenna transmission line to the rf
output connector on top of the 830B-1A cabinet.

ct. Make sure that the PLATE circuit breaker on
the front panel is set to OFF before making the power
connections. Connect the power input cable to the
transmitter. This power cable should be broughtfrom
an external fused cut-out box rated for 10 amperes.
Use AWG #12 wire or larger to make this connection.
Connect the power wires to terminals 1 and 2 of
TB301, located at the lower left corner of the transmitter cabinet as viewed from the rear. Connect the
neutral wire to terminal 3 of TB301. The power cable
may be brought into the transmitter through holes in
either the top o r bottom of the cabinet.
2.4

INTERNAL CONNECTIONS.

The 830B- l A 250-Watt FM Broadcast Transmitte r
pl a te and control circuit power transformers are
fitted with adjustable taps to compensate for line
voltage variations. These taps compensate for line
2- 1

STEAM POWERED RADIO.COM

installation

variations from 200 to 250 volts in 10-volt steps. To
adjust transformers T301 and T303 for line voltage
variations perform the following steps.
a. Measure the line voltage at the transmitter fused
cut-out box.
b. Remove the solder lug from T301, terminal 4,
and move it to the transformer terminal labeled
nearest the voltage measured in step a. Do not move
the solder lug from transformer terminal 5, because
this terminal supplies 230 volts to the cabinet fan for
all line input connections. See figure 2-2 for transformer terminal numbers versus input voltage.
c. Remove the solder lug from T303, terminal 5,
and move it to the transformer terminal labeled
nearest the voltage measured in step a. See figure 2-2
for transformer terminal numbers versus input voltage.
d.

Equipment is available that will completely control
and monitor transmitter operation from a remote
location through standard telephone pairs. When
such remote control equipment is used, necessary
installation and connection information will be supplied
with the remote equipment.
2.6

If the transmitter operating frequency is changed,
the following components will have to be changed
or adjusted. These components are ( 1) the exciter
power amplifier heterodyning oscillator crystal (2)
and the plate cavity slider.

Table 2-1 lists the channel frequency versus crystal
frequency and the Collins part number for each
crystal. Figure 2-4 shows the distance the plate
cavity slider should be positioned from the deck plate
(tube socket mounting plate) for each frequency within the 88- to 108-MHz range.

Tighten all transformer terminal connections.
2.7

The following connections on TB304 should be
checked to ensure that the plate on and filament off
functions will operate; TB304-1 to TB304- 2, TB304-3
to TB304-4, TB304-10 to TB304-11.
If the optional stereo generator is installed in the

field, the 18-db audio pad will have to be removed
from the audio circuitry of the exciter.
2. 5

FREQUENCY CHANGE.

REMOTE CONTROL.

Wired remote control of 830B-1A 250-Watt FM
Broadcast Transmitter can be accomplished by
connection to terminal boards. Figure 2- 3 shows the
terminal board connections and remote functions.
Remote ON switches should be the normally open,
momentary type. Remote OFF switches should be
operation, set the LOCAL-REMOTE switch, in the
transmitter cabinet, to REMOTE. With the LOCALREMOTE switch in the REMOTE position, the transmitter may be controlled ·from the wired remote
control panel or the transmitter panel switches.
For simplified ope ration, the FILAMENT ON and
PLATE OFF switches may be eliminated. The PLATE
ON switch starts a sequence of operation which turns
the filaments on and the plate voltage on after the
filament time delay has been completed. The FILAMENT OFF switch shuts down all transmitter functions.

STARTING THE TRANSMITTER IN A NEW
INSTALLATION.

Before starting the transmitter for the first time,
read section II of the unit instruction books to become
familiar with the location and function of the various
transmitter controls. Then, perform the following
procedure:

WARNING

I

Voltages are present in this transmitter
that are dangerous to life . Observe safety
precautions when making any transmitter
adjustments. Do not reach inside the rear
of the transmitter cabinets whenever high
voltages are applied. Do not depend on
door interl ocks. Always shut off transmitter power at the external cutout box
and ground all capacitors with the shorting
stick in the transmitter cabinet before
doing any work inside the rear of the
cabinets. When working in the power amplifier cavity, remember that 115 volts ac
is present on one side of the cavity compartment interlock. Keep metal tools away
from all transistor cases.

a. Complete the entire transmitter installation
procedure as directed in this instruction book.

If an optional stereo generator is employed in the

830B-1A, remote control of t he stereo mode may be
accomplished by a ground on TB302-7. If the ground
is present, the transmitter will be in the stereo mode.
If the ground is removed, the transmitter will be in
the monaural mode. Local control of the stereo mode
is also available at the transmitter.

2-2
STEAM POWERED RADIO.COM

b. Close the doors at the rear of the cabinet. Open
the doors at the front of the cabinet and remove the
lower front panel so that the entire inside panel is
exposed. Check that the plate cavity slider conforms
to the distance specified in figure 2-4 for the operating frequency. Close the cover on the plate cavity
compartment.

installation

7

.-----

-

A

7

I
0

= =

= =

0

~~

-I~

....

• I

-

ie

2 DIA KNOCK-OUT FOR
~lE WITH HIGHER POWER

-

38! I

16

r

2

~

•

3

1s DIA KNOCK-OUT ALTERNATE INPUT
LOCATIONS

-0

-

©

-1 ..

l

_J

~L~~
64i '·
19 ...L

31 :~

64

33¾:~~

4R

.

64 7

12':k
_j_ is
~

~
-1~'--

I '-....

+ I -I ~
RF OUTPUT
,.._,CD+ I
~
TYPE "N" SERIES
CONNECTOR

1_1

I

I

- -~- - ~

~~--'

' ""'- MON TOR OUTPUT

tOWER INPUT___,,,-~
I D GROMMET)

~ ALTER
FOR PiWAETR
E

I

~ID GROMMET- - ·

R~MOTE CONTROL LINE GROMMETS QTY- )

( 2 ID

~

::Jr

lz

,,, .,,

I

0
I

_/

'

II

I

I

0

I

'

-

2

- -

___,,,
_ _

----------,__ 3½ DIA KNOCK

OUT

\

_ ___j

LOCATION
INPUT

VIE
A-A
( OP)

-

Figure 2-1.
STEAM POWERED RADIO.COM

Outline and Installation D.
830B-1A 250-Watt FM B iagram,
Transmitter
road cast
2- 3/2-4

installation
HIGH VOLTAGE
T303

T301
250V 7 --...._
240V 6 - - 230V 5 - - - <
220V 4 - - - <
210V 3 - - 200 V 2 - - " "

[ 8}

250V
240 V
230V
220V
210V
200V

115 V
4.25 AMP

7 --6 ----<
5 ----<
4 ---<
3 ----<
2 ----<

9

Figure 2-2.

2100 V
250MA
DC OUTPUT
FROM FILTER

Transforme r Details

c. Set the PLATE circuit breaker on the front
panel to ON.
d. Press the FILAMENT ON switch. (Do not push
PLATE ON switch.) The green indicator lamp at the
top left of the cabinet should light. This means that
all transmitter tube filaments and cooling-air blowers
are operating.
e. Connect a VOM to TP301 and TP302. Set PA
FIL ADJ resistor R325 for an indication of 6.0 volts
on the VOM.
Note

A three (3) percent decrease in filament
voltage will extend the life of a cathode
fifty (50) percent.
When new, the 4CX250B tube will operate
satisfactori ly with less than 6.0 volts on
the filament. Initially set the filament
voltage for 6.0 volts at TP301 and TP302.
When the 830B-1A is properly tuned,
reduce the filament voltage to the point
where power output decreases, then increase it slightly.
As the tube ages, the filament voltage may
be increased to more than 6.0 volts.

f. Place the proper crystals into the exciter
sockets. The 14-MHz crystal is placed into the Y501
socket. The heterodynin g crystal is placed into the
Y426 socket. Turn on the exciter and allow it to warm
up for at least 15 minutes. The exciter POWER switch
should be left in the ON position at all times.
Turn SlOl to the 14 MC REF B position and

g.
check Ml0l for an indication in the B meter range.
Turn SlO l to the AFC KEY B position and check MlOl
for an indication in the B meter range.

Note

When Sl0l is in the AFC KEY B position
the meter pointer will not hold steady but
will pulse at the 5-Hz keying generator
rate. This pulse is an indication of normal
operation.
Turn Sl0l to the MOD OUTPUT B position and check
MlOl for an indication in the B meter range. If all
meter indications for the three Sl0l positions fall
within the B meter range, proceed with the following
power amplifier tuning procedures. If any of the
meter indications fall outside of the B meter range,
the modulator and afc discriminat or are out of adjustment and will have to be adjusted according to the
Modulator and AFC Discriminat or Adjustment Procedures in the Maintenance section of this instruction
book.
h. Switch SlOl to the MIXER GRID A position. Set
POWER OUT resistor R454 to its midposition . Using
a nonmetallic screwdriver type tuning tool adjust the
BUF TUNE control for a peak indication on meter
Ml0l.
Note

The MIX BAL control, R438, should be
placed in its midrange position. No further
adjustment of this control is then ne cessary
unless the transmitting frequency falls
within the range of 97 to 100 me. See step n
if the transmitted frequency falls within
this range.
i. Switch SlOl to the V428B position. Adjust L429
and L430 for a maximum indication on M 101.

j. Switch SlOl to the V429B position. Adjust L431
and L432 for a maximum indication on Ml0l.

2- 5
STEAM POWERED RADIO.COM

installation

FILAMENT ON

-t

TO TB303- I
SI
TO TB303-2
TO TB302 - 8

FILAMENT

O F F i S2
TO TB302 - 9
TO TB303 - 3

PLATE ON~

S3
TO TB303-7

PLATE

OFF

i

:

TO TB303-4

S4

T O TB303-5

TO TB302 -7

STEREO ON I OFF

~

CAUTION
SEE NOTE I

S7

•

FILAMENT O N ~ OS I

6.3V AC

~II~

TO TB303-2

:
:

TO TB303-I

115VAC

TO TB304-8

TO TB304-5

PL ATE ON ( 9 j~_
o_s_2_

II

__
G_.3_v_A
_c
~ ~ ~~11_s_v_A_c_ _ _ __

TO K302-IO

INCREASE

S6
POWER CHANGE

"'>------------------

TO TB334-4
TO TB334 - 2 SEE NOTE 2
TO TB334-5 SEE NOTE 4

DECREASE

TO TB303-8

4700

Ml

PLATE VOLTAGE
SE~ NOTE 3

TO TB303-10
TO TB303-9
4700
IOK
PLATE CURRENT
SEE NOTE 3

M2
TO TB303- IO
FORWARD
IOK

TO TB333-4

S5

t
POWER OUTPUT
SEE NOTE 3

O
REFLECTED

• TO TB333-5

M3

.01

TO TB303-IO

NOTES
I. CONNECT S7 ONLY IF STEREO GENERATOR
786M-I IS USED . IF CONNECTED TO AB30-2,
TURNING 57 ON WIL L SHORT THE 27 VOLT
SUPPLY
2.

IN THE

3.

MI, USE CPN 099 - 2323 -000
M2, US E CPN 099 - 2324 - 000
M3 , USE CPN 458 - 0638- 000
CONNECT $6 ONLY WHEN OPTIONAL OUTPUT POWER
ADJUST MOTOR IS INSTALLED

4.

8830 - 1, JUMPER T8334 -3 TO T8334- I

Figure 2-3,

2-6
STEAM POWERED RADIO.COM

Wired Remote Control Panel

installation

/

TABLE 2-1.

CRYSTAL PART NUMBERS
CRYSTAL
FREQ (MHz)

COLLINS
PART NUMBER

98. 1
98. 3
98. 5
98. 7
98. 9

84. 10000
84.30000
84. 50000
84.70000
84.90000

289 - 2794-000
289- 2795- 000
289-2796-000
289-2797-000
289- 2798-000

289- 2749-000
289- 2750-000
289-2751-000
289-2752-000
289 - 2753- 000

99.1
99.3
99.5
99.7
99.9

85. 10000
85.30000
85.50000
85.70000
85.90000

289-2799- 000
289-2800-000
289-2801-000
289- 2802-000
289-2803-000

76. 10000
76.30000
76. 50000
76.70000
76.90000

289-2754- 000
289-2755-000
289-2756-000
289-2757- 000
289 - 2758- 000

100. 1
100.3
100.5
100.7
100. 9

86. 10000
86. 30000
86.50000
86.70000
86.90000

289-2804-000
289-2805-000
289-2806-000
289-2807-000
289- 2808-000

91. 1
91. 3
91. 5
91. 7
91. 9

77. 10000
77.30000
77.50000
77.70000
77.90000

289 - 2759-000
289-2760-000
289 - 2761-000
289-2762-000
289- 2763- 000

101. 1
101. 3
101. 5
101. 7
101. 9

87. 10000
87.30000
87.50000
87.70000
87.90000

289-2809-000
289- 2810-000
289-2811-000
289-2812- 000
289- 2813-000

92. 1
92.3
92.5
92 . 7
92.9

78. 10000
78.30000
78.50000
78.70000
78.90000

289- 2764-000
289- 2765-000
289-2766-000
289- 2767-000
289-2768-000

102. 1
102. 3
102.5
102. 7
102.9

88. 10000
88.30000
88.50000
88.70000
88.90000

289-2814-000
289-2915-000
289-2816-000
289-2817-000
289-2818- 000

93.1
93.3
93.5
93.7
93.9

79. 10000
79. 30000
79 . 50000
79 . 70000
79.90000

289-2769-000
289 - 2770-000
289-2771-000
289-2772- 000
289-2773- 000

103. 1
103.3
103.5
103.7
103.9

89. 10000
89.30000
89.50000
89.70000
89. 90000

289 - 2819-000
289-2820-000
289-2821-000
289-2822-000
289- 2823- 000

94. 1
94.3
94. 5
94.7
94.9

80.10000
80.30000
80.50000
80.70000
80.90000

289-2774- 000
289-2775 - 000
289-2776-000
289- 2777- 000
289- 2778-000

104.1
104.3
104. 5
104.7
104.9

90. 10000
90.30000
90.50000
90.70000
90.90000

289-2824- 000
289 - 2825-000
289 - 2826-000
289-2827-000
289 - 2828-000

95. 1
95.3
95. 5
95. 7
95.9

81. 10000
81. 30000
81. 50000
81. 70000
81. 90000

289- 2779-000
289-2780- 000
289- 2781- 000
289-2782-000
289- 2783-000

105. 1
105.3
105.5
105.7
105.9

91. 10000
91. 30000
91. 50000
91. 70000
91. 90000

289-2829-000
289-2830-000
289- 2831-000
289-2832-000
289- 2833-000

96. 1
96. 3
96. 5
96.7
96. 9

82.10000
82.30000
82.50000
82.70000
82.90000

289-2784-000
289-2785-000
289- 2786-000
290-2787-000
289-2788-000

106. 1
106.3
106.5
106.7
106.9

92. 10000
92.30000
92.50000
92.70000
92.90000

289-2834- 000
289-2835-000
289- 2836-000
289-2837-000
289- 2838- 000

97. 1
97.3
97.5
97. 7
97. 9

83.10000
83.30000
83.50000
83.70000
83.90000

289-2789-000
289-2790-000
289-2791-000
289-2792-000
289-2793-000

107. 1
107.3
107. 5
107,7
107.9

93.10000
93.30000
93.50000
93.70000
93.90000

289-2839-000
289-2840- 000
289-2841-000
289-2842- 000
289-2843-000

CRYSTAL
FREQ (MHz)

COLLINS
PART NUMBER

88. 1
88.3
88.5
88.7
88.9

74.10000
74.30000
74.50000
74.70000
74.90000

289-2744-000
289-2745-000
289-2746- 000
289-2747-000
289-2748-000

89. 1
89. 3
89. 5
89. 7
89.9

75. 10000
75.30000
75.50000
75.70000
75.90000

90. 1
90.3
90.5
90.7
90.9

CHANNEL
FREQ (MHz)

CHANNEL
FREQ (MHz)

2-7
STEAM POWERED RADIO.COM

installation

k. Switch SlOl to the V430B position. Adjust L433
and L434 for a maximum indication on MlOl.
1. Switch SlOl to the V430C position. Adjust the PA
PLATE control for a minimum indication on Ml0l.
m. Set the MULTIMETER switch to GRID FS 40 MA.
Adjust first the exciter PA MATCH control, then the
power amplifier GRID TUNING control for a peak
MULTIMETER indication.
n. If the transmitter frequency falls between 97 and
100 MHz the following step will have to be completed.
Place a grid dip meter tuned to 98 MHz near the
exciter output. Adjust the MIX BAL control for a
minimum output as indicated on the grid dip meter.

w. Repeat steps u. and v. until the P.A. PLATE
CURRENT meter indicates the transmitter output
is 250 watts as measured by the indirect method. At
this time the PA screen current should be not less
than 5 ma or more than 20 ma. The indirect method
of measuring power output is:
Power Output = I E K
p p

Where K is efficiency, E is plate voltage, and I is
plate current.
P
P
Note

o. Set the POWER OUTPUT ADJUST control fully
counter clockwise.

It may be necessary to increase the exciter
drive to obtain 250 watts from the final.
Adjust the exciter POWER OUT control
until sufficient grid current is obtained.

p. Press the PLATE ON switch. The red indicator
lamp at the top right of the cabinet should light, and
the P.A. PLATE VOLTAGE meter should indicate
2100 ±100 volts.

x. Turn PA FIL ADJ resistor R325 counterclockwise to the point where power output decreases, then
slightly clockwise.

q. Set theMULTIMETERswitchtoSCREENVOLTAGE. The MULTIMETER should indicate 300 ±35 volts.
r. Adjust the PLATE TUNING control for a dip in
the P.A. PLATE CURRENT meter indication.
s. Set the WATTMETER switch to FORWARD.
Adjust the OUTPUT COUPLING control for approximately 5 ma of screen current.
t. Turn the POWER OUTPUT ADJUST control
approximately 2/3 of its maximum clockwise rotation.
u. Increase the transmitter coupling a small
amount by turning the OUTPUT COUPLING control
clockwise until the PA screen current is reduced to
approximately 10 ma. Adjust the PLATE TUNING
control for a dip in the P.A. PLATE CURRENT meter
indication. (The plate tuning capacitor should be near
its center position when the dip in power amplifier
plate current occurs. If the capacitor is not in this
position move the plate slider in the appropriate
direction and repeat step u.)
v. Rotate the POWER OUTPUT ADJUST control
clockwise a small amount.

2-8
STEAM POWERED RADIO.COM

y. Check to be sure that the FM monitor that is
connected to the transmitter is properly calibrated.
Then, if necessary, adjust the exciter VHF OSC
FREQ ADJ control until the monitor indicates that the
transmitter operating frequency is within specified
operating limits.
z. Apply a 50-Hz audio tone to the transmitter
input. Set the input level to +10 dbm ±2 db at the
transmitter audio input terminals.
aa. Adjust the exciter MOD GAIN control until the
monitor indicates 100 percent modulation.
ab. Replace the lower front panel on the transmitter
cabinet and close the front doors. The transmitter is
now ready for standard broadcast use.

Note

At this point it is suggested that a record
be made of all meter readings for future
maintenance and trouble shooting. These
meter readings may be recorded in table
5-3.

installation

PLATE CAVITY

20

19

18

17

16

;;,
w

:,:
0

15

~

w
(.)

z

14

I_

~
'

AFC
DISCRIMINATOR

i.-

REFERENCE
OSCILLATOR
AND AFC
LIMITERS

-

- - -•-

~;-• l

-·

EXCITER
POWER
SUPPLY

\

350V
0 EXCITER
I OWER AMPL

CONTROL
CIRCUITS

- IOV TO
KEYING GENERATOR

Figure 4-1.

STEAM POWERED RADIO.COM

!"

14 MHZ
REFERENCE
OSCILLATOR

300V
POWER
AMPL AND • - - - OS C PLATE
VOLTAGE
+20V
MODULATOR
AND AFC POWER
+ IOV TO
KEYING GENERATOR

,._

230 VOLT
60 HZ

115V
60 HZ

AUXILIARY
POWER
SUPPLY
T301

Block Diagram, 830B- lA 250- Watt FM
Broadcast Transmitter
4-3 / 4-4

'

secti on

5

main tenan ce
Note

GENER AL.

5.1

A three (3) percent decreas e in filamen t
voltage will extend the life of a cathode
fifty (50) percent .

The followin g paragra phs contain informa tion concern ing mainten ance of 830B-1A 250-Wa tt FM Broadc ast
Transm itter.

WARN ING

When new, the 4CX250B tube will operate
satisfac torily with less than 6.0 volts on
the filamen t. Initially set the filamen t voltage for 6.0 volts at TP301 and TP302.
When the 830B-1A is properl y tuned,
reduce the filamen t voltage to the point
where power output decreas es.

I

Voltage s are present in this transm itter
that are dangero us to life. Observe safety
precaut ions when perform ing any maintenance. Do not reach inside the transm itter
cabinet whenev er high voltage is applied.
Do not depend on door interloc ks. Always
shut down the transmi tter before doing any
work inside the transm itter cabinet. Immediately upon opening the rear cabinet doors
short out capacit ors C301 and C302 (located
in the lower right portion of the transm itter
cabinet) with the shorting stick provide d
with the transmi tter.

Refer to the applicab le unit instruc tions for specific
mainten ance procedu res for each subasse mbly.

As the tube ages, the filamen t voltage may
be increas ed to more than 6.0 volts.
d. Set Sl0 1 on the exciter to MIXER GRID A. Adjust
BUF TUNE control for a peak on MlOl.
e. Set Sl0l to V428B and adjust L429 and L430 for
a peak on MlOl.
f. Set SlOl to V429 B and adjust L431 and L432 for
a peak on MlOl.
g.

Set SlOl to V430 B and adjust L433 and L434 for

a peak on Ml0l.

5.2

NORMAL TUNING PROCE DURES .

The followin g are tuning procedu res which should be
observe d after the transmi tter has been installe d and
tuned accordi ng to the installa tion procedu res given in
section II. Table 5-1 present s abbrevi ated tuning
instruct ions to be used with the followin g procedu res.
Table 5-1 can be used separat ely when the operato r
become s familia r with the transmi tter.
a.

Open the doors at the front of the cabinet.

b. Press the FILAME NT ON switch and allow the
exciter to warm up for 15 minutes .
c. Connec t a VOM to TP301 and TP302. Set PA
FIL ADJ resisto r R325 for an indicati on of 6.0 volts
on the VOM.

h. Set SlOl to V430C B and adjust the PA PLATE
control for a minimu m indicati on on Ml0l.
1\ ot e
Conven ient marked ranges are availab le
on the meter which corresp ond to switch
p ositions . These ranges give an approxi mate require ment for min-ma x readings
on the particu lar switch position.
Tune the exciter coupling by setting the MULTIi.
METER switch to GRID FS 40 MA and adjustin g the
exciter PA MATCH control for maximu m coupling .
Tune the power amplifi er GRID TUNING control for
a peak MULTI METER indicati on.

5-1
STEAM POWERED RADIO.COM

maintenance

j.

Set the WATTMETE R to FORWARD.

k. Press the PLATE ON switch. In turn, adjust the
PLATE TUNING control for minimum indications and
increase the OUTPUT COUPLING control and the
POWER OUTPUT ADJUST control, by small amounts,
until the transmitter output power is 250 watts as
measured by the indirect method.
Power output = I E K
p p

The power amplifier screen current should not be
less than 5 ma nor more than 20 ma when the transmitter is properly tuned. Maximum efficiency can be
achieved when the WATTMETE R indication is maximum for a rated power amplifier plate current.
1.
Turn PA FIL ADJ resistor R325 countercloc kwise to the point where power output decreases, then
slightly clockwise.

m. Adjust the VHF OSC FREQ ADJ control until the
FM monitor indicates the transmitter is operating
within the specified operating limits.
5.3

MODULATOR AND AFC DISCRIMINATOR ADJUSTMENT PROCEDUR ES.

The wide-band exciter is designed to be exceptionally
stable and will require few adjustments over a l ong
period of time. The following adjustment procedures
should only be followed if the exciter is not operating
within limits upon installation, or if any of the
transistors (Q503 or Q511, Q601, or Q604) are
replaced. Replacement of other components should
not normally require a change in the adjustments
given in this section. The transmitter will have to
be ener gized when performing steps c and e. Use an
ac vtvm such as a Ballantine Model 310A when making
adjustments . A de vtvm such as a Heath type may be
used in step f.

~otc

When adjusting the modulator a nd afc section of the exciter, use a nonmetallic hex
type adjusting tool. Keep all metallic tools
a nd the hands or othe r parts of the body
away from transistor cases. When dis abling the afc, and the complete trans mitter is in operation, check the station
monitor to be sure the center frequency
stays within the FCC requiremen ts.

tuning. Set the controls midway between the limiter
fall of points shown on the vtvm. Do not replace Q509.
b. Tune the afc discriminat or by placing a vtvm
from TP501 to ground and tune the DISCR PRI control,
C515, for a maximum indication. P l ace the vtvm from
T P502 to ground and adjust the DISCR SEC control ,
C518, for O on the vtvm.
c. Disable the afc by pressing the AFC DISABLE
switch and adjust the OSC FREQ control until the
station monitor indicates that the exciter is on frequency. Replace Q509.
d . Remove Q607. Place a vtvm between TP602 and
ground. Tune L606 and L603 for a maximum indi cation
on the vtvm. Tune the inductors in the order shown
to minimize the effects of the limiter.
e . Remove afc by holding down the AFC DISABLE
switch. With the vtvm from TP602 and ground, tune
the DISCR PRI control, C639, for a maximum indication on the vtvm. Move the vtvm to TP601 and tune
the DISCR SEC control, C644, for a O indicati on when
the modulation monitor indicates the excite r is
approximately on frequency. Repeat the tuning of the
DISCR PRI and DISCR SEC controls. Replace Q607.
f. Place a de vtvm between TP603 and ground.
Set the AMP BIAS control for a 7. 5-volt indi cation on
the vtvm .
g. Place a vtvm between TP504 and gr ound . Remove
Q510. Tune L6 11 and L608 for a maximum indication
on the vtvm. Replace Q510.
h. With a vt vm on T P504 adjust the REF LEVEL
control for an equal indication on the vtvm with first
Q510 removed and then Q509 removed. This equalizes
the modulator oscillator voltage a nd the 14-MHz
refer ence voltage. Repl ace the transistors.
i. Place an oscilloscope between TP503 and gr ound.
Apply a 150-Hz audi o signal on J601. Adjust the MOD
BAL control for a minimum 150-Hz indi cation as shown
on the oscilloscope .

Not e

The MOD BAL control must be adjusted
s l owly to allow the error s ignal amplifiers
to stabilize between adjustments .
5.4

a. Remove transistor Q509 and place a vtvm from
TP501 to gr ound. Tune L505 for a peak indication on
the vtvm and tune L504 for a peak indication. Be
sure to tune the inductances in the order given to
minimize the limiting effect. Check that each stage
is limiting when making these adjustments . Limiting
will s how up as a b r oad fla t peak on the vtvm when
5-2
STEAM POWERED RADIO.COM

DISTORTIO N TESTING PROCEDUR E.

a . Refer to figure 5-1. Connect an audiofreque ncy
signal generator, such as a Barker & Williamson
Model 210, to the exciter audio input, terminals 1 and 2
of TB305. (Disconnect the station console a udio input
leads when making this connection. ) Connect a distortion and noise meter, such as a Barker & Williamson
Model 410, to the b r oadcast monitor. Connect a

maintenance

TABLE 5-1.

ABBREVIATED TUNING PROCEDURES

.
ADJUSTMENT

POSITION

CONTROL

INDICATING METER

INDICATION

R325

-

-

VOM

6. 0 volts

Sl0l

MIXER GRID A

BUF TUNE

Ml0l

Maximum

Sl0l

V428 B

*L429, L430

MlOl

Maximum

Sl0l

V429 B

*L431, L432

MlOl

Maximum

Sl0l

V430 B

*L433, L434

MlOl

Minimum

Sl0l

V430C B

PA (exciter)
PLATE

Ml0l

Minimum

PA MATCH
GRID TUNING

MULTIMETER

Maximum

PLATE TUNING

P .A. PLATE CURRENT

Near
minimum

OUTPUT
COUPLING

R.F. WATTMETER

Near 250watt
indication

MULTIMETER GRID FS 40 MA

WATTMETER

FORWARD

POWER OUTPUT R.F. WATTMETER
ADJUST

NOTES
Allow transmitter
to warm up at
least 15 minutes
before tuning.

Set as low as
possible, but
maintain 250 watts
output power.

Repeat the adjustment of PLATE
TUNING, OUTPUT COUPLING
and POWER OUTPUT ADJUST
controls until 250
watts is achieved
by the indirect
power measuring
method.
P = IE K
p p

*Use slotted nonmetallic screwdriver on these adjustments.

5-3/ 5-4
STEAM POWERED RADIO.COM

mainte nance

50-ohm artific ial load to the rf output conne ctor
locate d on top of the transm itter cabine t. Turn on the
transm itter.

5.5

b. Apply a 50-Hz audio tone to the transm itter
input. Set the input level to +10 dbm ±2 db at the
transm itter audio input termin als.
c. Adjust the excite r MOD GAIN contro l until the
monit or indica tes 100 percen t modul ation (±75-k Hz
deviat ion).
d. Measu re the distor tion at the freque ncies and
modul ation levels given in table 5-2. The distor tion
shall be less than 1.5 percen t for freque ncies betwe en
50 and 100 Hz, less than 1.0 percen t for freque ncies
betwe en 100 and 7500 Hz, and less than 1.5 percen t
for freque ncies betwee n 7500 and 15,000 Hz.

saw 210
AUDIO FREQUENCY
SIGNAL
GENERATOR

TB305
I AND 2.

AUDIO FREQU ENCY RESPO NSE MEASURE MENT S.

a. Refer to figure 5-2. Conne ct an audiof requen cy
signal genera to_r, such as a Barke r & Willia mson
Model 210, to termin als 1 and 2 of termin al board
TB305 . (Disco nnect the station consol e audio input
leads when makin g these measu remen ts.) Conne ct a
vacuu m-tub e voltme ter, such as a Ballan tine Model
310A, to the audio output termin als of the audio frequency genera tor. Conne ct a 50-ohm artific ial load to
the rf output conne ctor locate d on top of the trans mitter cabine t. Turn on the transm itter.
b. Check the audio freque ncy respon se of the transmitter by modul ating the transm itter at 50, 100, 400,
1000, 5000, 7500, 10,000 , and 15,000 Hz for 25 percen t,

8308-I A
TRANSM ITTER

RF OUTPUT

-

50 OHM
ARTIFIC IAL
LOAD

MONITOR
OUTPUT

r'\

I
86W 410
DISTOR TION
AND
NOISE METER

FREQ UENC Y
Hz

900C
BROADCAST
MONITO R

Figure 5-1.

Distor tion Test Setup

TABL E 5-2.

DISTORTION CHECKS
DISTORTION IN PERC ENT

25% MODULATION

50% MODULATION

100% MODULATION

50
100
400
1000
5000
7500
10,000
15,000
5-5
STEAM POWERED RADIO.COM

maintenan ce

saw 210
AUDIO FREQUENCY
SIGNAL
GENERATOR

TB305
IAND 2

8308-1 A
TRANSMITTE R

RF OUTPUT

~

50 OHM
ARTIFICIAL
LOAD

MONITOR
OUTPUT

"
BALLANTINE
MODEL 310A
VTVM

Figure 5-2.

900C
BROADCAST
MONITOR

Audio Frequency Response Test Setup

50 percent, and 100 percent modulation . Audio frequency response is measured by keeping the percentage of modulatio n constant and measuring the
magnitude of audio, at each frequency given, to give
the oesired percentag e of modulation . The audio frequency response must fall within the limits given in
figure 5-3.

d. Remove the signal generator . Set the DECIBEL S
switch for an indication on the 900C meter. The
monaural, fm, signal-to- noise ratio is the algebraic
sum of the DECIMAL switch and the meter indication.
e. The FM noise level should be 65 db below 100
percent modulation .
5. 7

Note

When taking audio frequency response
measurem ents a broadcast monitor, such
as a Collins 900C, should be used. Do not
use an instrumen t where audio deemphas is
might give a false indication of peak
modulatio n.
5.6

FM NOISE MEASURE MENT.

To measure FM noise (monaural signal-to- noise ratio)
with the Collins Modulatio n Monitor 900C perform the
following procedure . Refer to figure 5-4.
a. On the 900C, set the METER switch to the
TOTAL MOD position and the DECIBEL S switch to the
0 position.
b. Connect the Barker and Williamso n Model 210
signal generator output to audio input terminals
TB305-1 and TB305-2. Set the signal generator to
400 Hz and modulate the transmitte r 100 percent.

c. On the 900C, set the DE-EMPH ASIS switch to
the IN position and the METER switch to the MAIN
CHAN AUDIO position. Set the METER ADJUST control for an indication of O db on the 900C meter.

5-6
STEAM POWERED RADIO.COM

AM NOISE MEASURE MENTS.

To measure AM noise with the Collins 900C, perform
the following procedure . Refer to figure 5-5.
a.

Connect TB305-1 to TB305-2 on the transmitte r.

b. Connect a vtvm to the AM NOISE jack on the
900C.
c.

Turn on the transmitte r.

d. On the 900C, set the METER switch to the RF
LEVEL position. Adjust the RF LEVEL control for an
indication of 100 percent on the 900C meter.
e. Record the AM noise voltage indicated on the
vtvm. The AM noise voltage should be referenced to
a carrier level of 1 volt rms. The AM noise level
should be 55 db below the carrier level.
5.8

TROUBLE SHOOTING.

Standard trouble-sh ooting procedure s should be used in
finding malfunctio ns in the transmitte r. As is suggested in TB-536 and TD-538, meter indication s for
all functions should be recorded when the transmitter is installed and operating properly. Table 5-3
is supplied for recording these readings. If some
malfunctio n should occur after the normal meter

,,

maintena nce

readings are recorded , it is a simple matter to compare the meter readings of the malfunct ioning equipment with the normal meter readings . When troubleshooting and comparin g the meter readings it is
advisable to start with the final stage and proceed
backwar ds until normal readings are encounte red. The
malfunct ioning stage will then be the one immedia tely
ahead of the normal meter indicatio ns .

...

As most cases of trouble will be traced to tubes or

transisto rs, it is advisabl e to first of all replace the
tube (or transisto r) in the stage in which the trouble
is suspecte d. If the trouble does not clear with tube

or transisto r replacem ent, it will become necessar y
to take resistanc e or voltage measure ments, within
the suspecte d circuit, to determin e which compone nt
has failed.
When tracing trouble within the power amplifie r it will
be helpful to use the "from-to " informat ion given in
unit instructi ons TD-538. The "from-to " informat ion
gives the actual location of the individua l wires within
the power amplifie r cabinet. When used in conjuncti on
with the schemat ic, the "from-to " informat ion can be
very helpful.

18
I

16
STANDARD PRE EMPHASIS CURVE
14

12

I

TIME CONSTANT = 75 MICROSECONDS
(SOLID LINE)
FREQUEN CY RESPONSE LIMITS
SET BY
SO LID AND DASHED LINES

,.,

II

.,

I

10
I

8

-~

I

en
__,

llj

u
w

I

6

I

I

0

.,

.,.,

I

4

-

I

~

I

I

2

"
I
I

0

_, ,,

-2
-4
10

,

100

1000

1opoo

30,000

FREOUE~C Y (HERTZ)

Figure 5-3.

Audio Frequenc y Respons e Limits

5-7
STEAM POWERED RADIO.COM

mainte nance

saw 210
AUDIO FREQUENCY
SIGNAL
GENERATOR

TB305
I AND 2

RF OUTPUT

8308-1 A
TRANSM ITTER

~

-

MONITO R
OUTPUT

BALLAN TINE
MODEL 310A
VTVM

900C
BROADCAST
MONITOR

~

Figure 5- 4.

FM Noise Test Setup

TB305
PIN I
SHORT

I

8308-I A
TRANSM ITTER

RF OUTPUT

TB305
PIN 2
MONITOR
OUTPUT

'
BALLAN TINE
MODEL 310A
VTVM

900C
BROADCAST
MONITO R

Figure 5-5.

5-8
STEAM POWERED RADIO.COM

AM Noise Test Setup

50 OHM
ARTIFIC IAL
LOAD

50 OHM
ARTIFIC IAL
LOAD

maintenance

TABLE 5-3. NORMAL TRANSMITTER METER INDICATIONS

CONTROL

~

METER

POSITION

S101

BUFFER GRID A

Ml0l

S101

MIXER GRID A

Ml0l

Sl0l

V428 B

Ml0l

S101

V429 B

MlOl

Sl0l

V430 B

Ml0l

S101

V430C B

MlOl

S101

MOD OUTPUT B

MlOl

S101

AFC KEY B

Ml0l

Sl0l

14 MC REF B

MlOl

MULTIMETER

SCREEN FS 400 VDC

MULTIMETER

MULTIMETER

SCREEN FS 40 MA

MULTIMETER

MULTIMETER

GRID FS 40 MA

MULTIMETER

-

~

----

---------------

---------------

INDICATION

P.A. PLATE
VOLTAGE
P.A. PLATE
CURRENT
R.F . WATTMETER

5-9/ 5 - 10
STEAM POWERED RADIO.COM

A830-2 10

w

Wide-Band FM Bro2.dcast Exciter

523-07553 03 - 101418

•

•

STEAM POWERED RADIO.COM

Unit Instructions

TD-536
523-0755303-101418
1 May 1962
1st Revision, 15 April 1964

~

COLLINS

~
unit instructions

A830-2

lOW Wide-Band FM
Broadcast Exciter
© Collins Radio Company 7962, 7964

Cedar Rapids D ivision

I

Collins Radio Company, Cedar Rapids, Iowa
p,, ., ted , n U S •

STEAM POWERED RADIO.COM

TABLE OF CONTENTS
Page

Section

I

GENERAL DESCRIPTION

3

1.1
1.2

3

1.3
1.4

1.5
1.6
II

III

General . . .
Purpose of Equipment
Equipment Supplied . .
Equipment Required but not Supplied
Technical Summary . . . . . . . .
Vacuum-Tube, Fuse , and Semiconductor Complement.

3
4

4
4
5

PRINCIPLES OF OPERATION

8

2.1
2.2
2.2.1
2.2.2
2.3
2.3.1
2.3.2
2.3.3
2.3.4

8
8
8
9
9

General . . . . .
Frequency Modulation Methods .
Phase Modulators . . . .
Direct Frequency Modulation
Block Diagram . . . . . . . . .
Modulator . . . . . . . . .
Automatic Frequency Control
Power Amplifier
Power Supply

9
9
10
10

MAINTENANCE

15

3.1
3.2
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.3.6
3.3.7
3.3.8
3.3.9
3.3.10
3.3.11
3.3.12
3.3.13

15
15
15
15
15
15
15
16
16
16
16
16
16
16
17
17
17
17
17
17
17
17
17

3.4
3.4.1

3.4.2
3.4.3
3.4.4
3.4.5
3.4.6

General
Test Equipment Required
Alignment and Adjustment
Preliminary Adjustments
Modulator Limiter-Discriminator Alignment
Modulator Output Amplifier Tuning .
AFC Buffer Tuning . . . .
FM Oscillator Adjustment .
Modulation Discriminator .
Amplifier Bias Adjustment
Modulator Gain Adjustment
AFC Limiter-Discriminator Alignment
Reference Level Adjustment . .
Baseband Canceling Adjustment . . .
AFC Loop Check . . . . . . . . . .
Power Amplifier Adjustment and Tuning
Minimum Performance Standards
Preliminary Adjustments
Frequency Response
Harmonic Distortion . .
Residual FM Noise . . .
Carrier Frequency Shift
AM Noise Measurement .

IV

PARTS LIST

V

ILLUSTRATIONS

18

31

1
STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

LIST OF ILLUSTRATIONS
Figure
1-1
1-2
2-1
2-2
2-3
2-4
2-5
3-1
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
5-1

Page
A830-2 10 W Wide-Band FM Broadcast Exciter , Over-all View (C859-15-P)
A830-2 10 W Wide-Band FM Broadcast Exciter, Rear View (C859-16-P) . .
Direct FM Modulation, Simplified Block Diagram (C859-14-3) . . , . , . .
A830-2 10 W Wide-Band FM Broadcast Exciter, Block Diagram (C859-04-5)
Reference Switch, Simplified Schematic and Mechanical Analog Diagram (C859-12-3)
Baseband Cancel Switch, Simplified Schematic and Mechanical
Analog Diagram (C859-ll-3) . , . . . . . . . . . . .
Synchronou s Detector. Simplified Schematic and Mechanical
AnalogDiag ram (C859-17-3) . . . . . . . . . . . . .
Reference Level Adjustment, Oscilloscop e Patterns (C859-18-2) .
Modulator Compartme nt, Component (Except Resistors) Identificatio n (C859-07-P)
Modulator Compartme nt, Resistor Identificatio n (C859-08-P) .
. . . .
AFC Compartme nt, Component (Except Resistors) Identificatio n (C859-09-P) . . .
AFC Compartme nt, Resistor Identificatio n (C859-10-P) . . . . . . . . . . . . .
Power Amplifier Compartme nt, Component (Except Resistors) Identificatio n (C859-05-P) .
Power Amplifier Compartmen t, Resistor Identificatio n (C859-06-P)
Power Supply, Component Identificatio n (C859 -03-P) . . . . . • .
Chassis, Component Identificatio n (C859-19-P ) . . . . . . . . .
A830-2 10 W Wide-Band FM Broadcast Exciter, Schematic Diagram (C859-01-6)

3
7
8
11

12
13
14
16
24
25
26
27
28
28

29
30
31

LIST OF TABLES
Table
1-1
3-1

Page
Vacuum-Tu be, Fuse, and Semiconduc tor Complemen t
Test Equipment Required . . . . . . . . . . . . .

2
STEAM POWERED RADIO.COM

5

15

TD-536
A830- 2 10 W Wide- Band FM Broadcast Exciter

SECTION I
GENERAL DESCRIPTION
1. 1 GENERAL.

1.2 PURPOSE Of EQUIPMENT.

This instruction book contains information for operation and maintenance of A830-2 10 W Wide-Band FM
Broadcast Exciter. See figure 1-1. The A830-2 is
manufactured by Collins Radio Company, Cedar
Rapids , Iowa.

The A830-2 10 W Wide-Band FM Broadcast Exciter
is a direct FM exciter designed specifically to m eet
the stringent requirements of stereophonic FM broadcasting. - The A830-2 m ay be used in monaural broadcasting, storecasting (SCA), or with Collins 786M-1

0

0

"

"

"

"
0

~

.i~:,

:••"·

"

"

0

";~:"~

..

fl°i~

00

"

g

"0

" "

v ·c ·c '""'

"

"

"

I.)

t) Olps:f

"
.\_. ii~~
"
"
'""'·
.
l! \. ~;'i~• Jm,

~

"

JWl, ·• ~

••
0

"

(I

"

Q

· •

·c .,
"

...... ., ... - - - . - - - - ---~··

AFC OISA8l.(

.,

.;,,,w

(;j ~ ~
~ ,.t

{j

"~

,c.:n .C

~

~""'
-

~~

......

~ ltfAS

~

M¢ D!;,/JK

4)

0

~~

r,-Wl

,.

...

,.)

.,

ii

...

,.

·•=,

0
ucc :,:;:•

;r:. '1t" .•

""'

~..i,r..a.

"

0

(!

w~

....

()
,@.$<.c«.ft

PO)'tER

(el

~-~;el.~
f t!U

Figure 1-1. A830-2 10 W Wide-Band FM Broadcast Exciter, Ove r-all View
3
STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter
Stereo Generator (optional} for stereophonic broadcasting. The A830-2 is used to drive higher power
amplifiers in the FM broadcast service.

The A830-2 mounts in the same cabinet as the first
stage of amplification (250 or 1000 watts) in the
transmitter. A rear view of the A830-2 is shown in
figure 1-2.

1.3 EQUIPMENT SUPPLIED.
1.4 EQUIPMENT REQUIRED BUT NOT SUPPLIED,

The A830-2 is normally supplied as apart of a Collins
FM transmitter (830B-1A. 830D-lA, 830E-1A, etc.).

The A830-2 is supplied with all required equipment.

l .5 TECHNICAL SUMMARY.

Ambient temperature range

• +l0°C(+50°F} to +55°C(+l31 °F).

Ambient humidity range .

. 0 to 95 percent relative.

Altitude . . . . . .

. 7500 feet, maximum.

Shock and vibration .

. Normal handling and transportation.

Power source

. 117 volts ±5 percent, 50/ 60 cps, single phase.

.

R-f power output

. Adjustable to 10 watts into a 50- to 70-ohm resistive
load.

Frequency range . . . . . . . . . . . . . . . . . . • 88 to 108 me . Customer frequency is determined by
one crystal in the heterodyning oscillator circuit.
Carrier frequency stability . . . . . . . . . . . . . . Varies less than ±1000 cps with an ambient temperature range of +l0°C(+50°F) to +55°C(+131 °F), and a
line-voltage range of ±5 percent.
Harmonic and spurious radiation . . . . . . . . . . . • Any emission appearing on a frequency r e moved from
the carrier by between 120 kc and 240 kc, inclusive,
is attenuated at least 30 db below the level of the
unmodulated carrier.
Any emission appearing on a frequency removed from
the carrier by more than 240 kc up to and including
600 kc is attenuated at lea st 40 db below the level of
the unmodulated carrier.
Any emission appearing on a frequency removedfrom
the c arrier by more than 600 kc is attenuated at least
80 db be low the level of the unmodulated carrier,
with the exception of harmonics of the r-f carrier
which complies with the requirements of the particular
transmitter in which the A830 -2 is installed .
Type of modulation . . . . . . . . . . . . .

100 percent m odulation is
. Frequency modulation.
defined as ±75-kc deviation of the main carrier.

Exciter inputs . . . . . . . . . . . . . . . . . . . . Stereophonic channel: 600 ohms, unbalanced. Input
of 0.1 volt (approximately) required for 100 percent
modulation.
Monophonic channel: 600 ohms, balanced. Input of
10 dbm ±2 db (approximately 2.45 volts) required for
100 percent modulation.
4
STEAM POWERED RADIO.COM

....--.,

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter
Input of 0.35
SCA channel: 600 ohms, balanced.
volt
(approximately)
required for 10 percent
modulation.
Frequency and phase response . . . . . . . . . . . . • The frequency and phase response of the A830-2 is
such that when used with a suitable stereophonic
generator such as the 786M-l, stereophonic separation
between left and right stereophonic channels shall be
better than 35 db at audio modulating frequencies
between 30 and 15,000 cps.
Distortion . . . . . . • . . . • . . , . • . . • . • • Does not exceed 0.5 percent in the 30- to 15,000-cps
frequency range and 1.0 percent in the 15,000- to
75,000-cps frequency range.
Pre-emphasis .

. Standard 75-microsecond pre-emphasis.

FM noise level .

. 65 db below 100 percent modulation.

AM noise level .

. 55 db below 100 percent AM level.

1.6 VACUUM-TUBE, FUSE, AND SEMICONDUCTOR COMPLEMENT.

Table 1-1 lists all of the vacuum tubes, fuses, and semiconductors used in the A830-2.

TABLE 1-1. VACUUM-TUBE, FUSE, AND SEMICONDUCTOR COMPLEMENT

SYMBOL

FUNCTION

TYPE

V426
V427
V428
V429
V430

6U8A
12AT7
6AU6
5763
2E26

Oscillator and buffer
Balanced mixer
Limiter-amplifier
Driver
Power amplifier

Q501
Q502
Q503
Q504
Q505
Q506
Q507
Q50,8
Q509
Q510
Q511

2N1225
2N1225
2N708
2N1613
2N1613
2N1613
2N1613
2N491
2N1605
2N1605
2Nll 75A

First afc limiter
Second afc limiter
Afc discriminator driver
First error signal amplifier
Second error signal amplifier
Third error signal amplifier
Fourth error signal amplifier
Keying generator
Multivibrator
Multi vibrator
Baseband cancellation amplifier

Q601
Q602
Q603
Q604
Q605
Q606
Q607
Q608

2N1396
2N1225
2N1225
2N708
2N1225
2N708
2Nl 711
2N1396

Frequency modulated oscillator
First limiter
Second limiter
Discriminator driver
Afc buffer
Modulator output amplifier
First baseband amplifier
Second baseband amplifier

CR401
CR402
CR403
CR404
CR405

1N1492
1Nl492
1Nl492
1N1492
1N1492

B+
B+
B+
B+
B+

rectifier
rectifier
rectifier
rectifier
rectifier
5

STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Ban d FM Broadcast Exciter
TABLE 1-1. VACUUM - TUBE, FUSE, AND SEMICON DUCTOR COMPLEM ENT (Cont)
SYMBOL

TYPE

FUNCTION

CR406
CR407
CR408
CR409
CR410
CR411
CR412
CR413
CR414
CR415
CR426

1N1492
1Nl492
1N1492
1N538
1N538
lOMl0ZBl
lZlOV0l
1N538
1N538
lZl0V0l
1N977A

B+ rectifier
B+ rectifier
B+ rectifier
+20- volt rectifier
+20-volt rectifier
+20 - volt regulator
+10-volt regulator
-10-volt rectifier
-10-volt rectifier
-10-volt regulator
Oscillator plate voltage regulator

CR501
CR502
CR503
CR504
CR505
CR506
CR507
CR508
CR509
CR510
CR511
CR512
CR513
CR514

1N270
1N270
1N270
1N270
1N270
1N270
1Nl98
1Nl98
FA-4000
FA-4000
FA-4000
1N198
1Nl98
1N718

Gate
Gate
Afc limiter
Afc limiter
Afc limiter
Afc limiter
Afc discrimin ator
Afc discrimin ator
Synchrono us detector
Synchrono us detector
Gate
Meter rectifier
Meter rectifier
Voltage regulator

CR601
CR602
CR603
CR604
CR605
CR606
CR607
CR608
CR609
CR610

1N626
SV3173
1N270
1N270
1N270
1N270
1Nl98
1N198
1N751A
1N198

Temperat ure compensa tion
Voltage regulator
Limiter
Limiter
Limiter
Limiter
Modulatio n discrimin ator
Modulatio n discrimin ator
Voltage regulator
Meter rectifier

F401
F402

1 amp
1/ 4 amp

Protect T401
Protect T402

6
STEAM POWERED RADIO.COM

TD-536

A830-2 10 W Wide-Band FM Broadcast Exciter

u
Q xoso1

csosQ
X0601 Q

u

B
B

g

MODULATOR CIRCUIT
X0602Q
Qxoeoa

' L608Q

I
I

Q

!

XQ606

I"

XQ603

L606~

T504

~538

0

CS37

C515 1503

QL603

XQ605

OC639

..,

.,

c:::,

XY501

8

X0508 X0509 XOSIO

0

0

RS72

0

LJ J<0I
L -130

XY426

C)

0

V

AUTOMATIC FREQ CONTROL CIRCUIT

POWER AMPL CIRCUIT

U,

C536

Q xos12

e
0

8

V

T601

Qxo&o7

R562

~

xoso,o

I

X '/426

8

QL504

: Go
0

cmQQ

Qxosn

Qxo502

..."'

v

C532

QL505

mo

o o

C

B

xosoaQ

X0'-04

l61!Q

t{j

·~· E]'O' 'O'

•
•

C431 QxV427

OR438

lAZ9

•
•

L432

0

Xl/428

L433

OD

XV429

•

.8

8 1/

C475

n

C4 63

\O

C 459 C457

IS0V0C

C478 C462
6 .3VAC -I0V0C

300VDC

LJ Q

XV430

6.3VAC

L431

...

J 402

l434

C408
350VOC
/

n .. n n n n

•

Q

V

~-· ;q;.~
~

•

F-r

• tt~~•~~~~I~
-----Figure 1-2. A830-2 10 W Wide-Band FM Broadcast Exciter, Rear View

7
STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

SECTION II
PRINCIPLES OF OPERATION
2. 1 GENERAL.

system has been used widely in broadcast FM transmitters in the past.

This section describes the principles of operation of
A830-2 10 W Wide-Band FM Broadcast Exciter.
Figure 2-2 is a block diagram of the A830-2 and
figure 5-1 is the schematic diagram of the A830-2 .
Refer to these figures for the following discussion.
2.2 FREQUENCY MODULATION METHODS.

There are two basic methods used to generate an
FM signal, direct FM and phase modulation. There
are variations of each of these two methods, but the
end results are the same.
2.2. 1 PHASE MODULATORS.
The phase modulation method consists of phase modulating a CW (continuous wave) signal with audio tones.
The audio response is shaped to drop off 6 db per
octave from the lowest to the highest frequency.
The resultant signal is frequency modulated although
produced by a phase modulator . The modulation index
of an FM signal is defined as the ratio of the change in
carrier frequency (deviation) to the modulating frequency,

Ymf.

The modulation index of present phase

modulators is so low that modulation is usually
performed at a low frequency (approximately 100 kc)
and then multiplied about 800 times to obtain the
output frequency with the desired ±75-kc deviation.
The outstanding advantage of this system is that the
100-kc oscillator may be crystal controlled and
further frequency stabilization is not required. This

The arrival of stereophonic FM broadcasting has
caused problems in the phase modulator. A composite
stereo plus SCA signal (referred to hereafter as the
baseband audio signal) occupies a frequency band
from 50 cps to 75 kc. The audio response shaping
(6 db per octave) would require that 50-cps signals
be 65.5 db above signals at 75 kc. When a signal-tonoise ratio of 65 db and a dynamic range of approximately 60 db is added to this, it is obvious that
baseband amplifiers cannot be built to meet these
requirements.
It is possible to split the phase modulation into two
steps where one phase modulator accepts only the
L + R (left and right audio signals) audio spectrum and
a subsequent modulator adds the L - R double-sideband
suppressed carrier signal. The audio bandwidth for
each phase modulator is thereby reduced and the
dynamic range of the baseband amplifiers is reduced
to acceptable limits. The phase and amplitude relationships must be maintained between the two signals.
These requirements are ±0.3-db gain variation and
±3-degree phase variation to meet the 30-db stereo
separation requirement. These requirements would be
difficult to obtain without frequent on-the-air adjustment to continually meet the stereo separation
requirement.

There are other methods of splitting the signal and
using more than one modulator, but all have the phase
and gain stability problem.

DISCRI MINATOR

COMPOSITE
STEREO
SIGNAL

BASEBAND
AMPLIFIER

14-MC FM
OSCILLATOR

LIMITER

AFC

Figure 2- 1. Direct FM Modulation, Simplified Block Diagram
8
STEAM POWERED RADIO.COM

FM
OUTPUT
14 MC

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

2.2.2 DIRECT FREQUENCY MODULATION.
The direct method of generating a frequency modulated signal is shown in figure 2-1. The complete
stereo signal (and SCA signal if used) is fed through
a baseband amplifier to a frequency-modulated oscillator. The discriminator completes an audio feedback
loop which suppresses FM oscillator distortion,
incidental FM noise, transient carrier offset, and
gain/phase variation in the baseband amplifier and
modulator. The center frequency of the oscillator is
not sufficiently stable so an automatic frequency control (afc) circuit is required to maintain frequency
stability. The output of the modulator is a 14-mc FM
signal with ±75-kc peak deviation. The output frequency is obtained by translating this signal with a
stable vhf oscillator. The use of the direct FM system
removes the requirement for double modulators, phase
delay lines, and baseband amplifiers with a response
which changes with frequency.
2.3 BLOCK DIAGRAM,

Refer to figure 2 - 2, a block diagram of the A830-2.
2.3.1 MODULATOR.
The A830-2 uses the direct FM method of generating
an FM signal. The baseband input (and SCA input, if
used) is connected to baseband amplifiers Q607 and
Q608.
The response of these amplifiers is flat.
The gain of the baseband amplifiers is adjustable with
AMPL BIAS control R641. Refer to figure 5-1. The
emitter voltage on Q608 is regulated to +15 volts by
a silicon breakdown diode, CR609. The output of Q608
is coupled to frequency-modulated oscillator Q601.
Q601 is an LC oscillator which has a center frequency
of 14 me. The tuned circuit in the base of Q601
contains a voltage-sensitive capacitor, C654. Refer
to figure 5-1. The capacitance of C654 varies proportionately with the voltage across it. The change
in capacity of C654 makes a corresponding change in
the frequency of oscillations in Q601.
Thus, the
frequency deviation of the output of Q601 is directly
proportional to the amplitude of the modulating signal
and the peak deviation is ±75 kc.
The output of Q601 is coupled to two limiters, Q602
and Q603.
The limiters remove any amplitude
modulation from the FM signal. This amplitude
modulation is caused by variation of the tuned circuit
capacity by the baseband signal. The transistors do
not do any limiting. The limiting takes place in the
diodes connected to the collectors.
This method
provides symmetrical limiting (positive and negative)
which avoids the phase modulation that occurs when
unsymmetrical clipping followed by filtering is used.
The limiters are set up so that as the input level is
raised, the second limiter operates first; just before
it becomes nonlinear, the first limiter starts limiting.
The limiting range is approximately 31 db.

The output of the second limiter is coupled to
discriminator driver Q604. One output of the discriminator driver is connected to modulator discriminator T601 and the other output goes to output amplifier
Q606.
Modulator discriminator T601 converts the frequencymodulated 14-mc signal to art AM signal which is
detected by diodes CR607 and CR608. The detected
audio is mixed with the input baseband audio at the
input to the baseband amplifiers. This feedback loop
suppresses distortion from the FM oscillator, incidental FM noise, transient carrier offset, andgain/phase
variation in the baseband amplifier and modulator.
Output amplifier Q606 provides a signal output of 1.0
volt rms for the balanced mixer in the power amplifier
compartment. This output is matched to 50 ohms by
an L-section impedance, L611 and C634. A low-pass
filter, C632, C633, and L610, attenuates harmonics
of the 14-mc signal.
A portion of this output is
rectified and connected to meter switch S101 for
monitoring purposes.
The second output from Q606 is coupled to afc buffer
amplifier Q605. This amplifier, as well as the limiters
and amplifiers preceding it, reduces oscillator frequency change caus.ed by variation of loading on the
output.
The output of Q605 is 0.1 volt rms across
50 ohms.
2.3.2 AUTOMATIC FREQUENCY CONTROL.
The A830-2 requires automatic frequency control to
maintain the center frequency of the modulated
oscillator at 14 me. The error in frequency of this
oscillator may be caused by temperature drift,
carrier shift due to distortion in the modulator, etc.
The afc circuits correct these errors to bring the
stability of the output frequency to ±1000 cycles per
second over a temperature range of + l0°C(+50°F)
to +55°C(+131 °F) and a line voltage range of ±5
percent.
The afc correction voltage is obtained by comparing
the modulator output signal with the output of a
crystal-controlled reference oscillator, and deriving a
d-c voltage which is proportional in magnitude and
polarity to the magnitude and direction of the difference in frequency of these two signals.
The reference oscillator is a conventional crystalcontrolled oscillator using a fundamental 14-mc
series-resonant crystal. The temperature drift of
this crystal contributes only ±70 cycles per second
to the output frequency drift over temperature.
The signal from afc buffer Q605 and the output from
the reference oscillator a re connected to a diode
switch, CR501 and CR502. The diode switch is simply
two diodes which are alte rnately switched on and off
by the 5-cps square wave. The diode switch is controlled by a signal from keying generator Q508. This
9

STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter
signal, a square wave with a frequency of approximately
5 cps, alternately couples the reference signal, then
the modulated carrier, to the input to first limiter
Q501.
The two limiters, Q501 and Q502, and discriminator
driver Q503 are identical to the limiters and driver
(Q602, Q603, and Q604) used in the modulator. The
limiters remove any amplitude difference which might
exist between the two signals. The level of the
reference signal is adjustable with REF LEVEL control
R572. Q503 amplifies the limited signal to a level
sufficient to drive the afc discriminator. Assume that
there is no modulation applied. In this case, the output
from the discriminator will be a 5-cps square wave
with an amplitude proportional to the frequency error
in the FM oscillator.
The 5-cps error signal is amplified and applied to the
synchronous detector which develops the d-c correction voltage. This d-c voltage is coupled through a
low-pass filter to the voltage-sensitive capacitor in the
frequency-modulated oscillator to tune the FM oscillator back on frequency.
The operation of the afc circuitry is only slightly
different when modulation is applied at ±75-kc deviation. Assume now that modulation is applied and an
error of 100 cps exists in the FM oscillator. The
output of the afc discriminator due to the 100-cps
·signal would be 100 Kd where Kd is the gain of the
discriminator in volts per cps. The output of the
discriminator due to the modulation on the carrier
would be 150,000 Kd. This means that the undesired
signal is 1500 times greater than the desired signal.
The undesired signal is removed by the modulation
canceling circuit consisting of baseband cancel amplifier Q511 and diode switch CR511. Whenever the
modulated carrier is connected to the first limiter
diode switch, CR501 and CR502, the baseband audio
input is connected to the discriminator output by
diode switch CR511.
This baseband audio is 180
degrees out of phase with the discriminator output,
and when MOD BAL control R652 is properly adjusted,
the output of the afc discriminator due to modulation
is completely canceled. The 5-cps error signal due
to the frequency error in the FM oscillator is then
amplified and detected as if modulation were not
applied.
Note that the afc discriminator is used as a comparator rather than as a reference. The exact center
frequency of the discriminator is not important since
the output voltage need only be proportional to the
difference in the two frequencies rather than to the
absolute value of these frequencies. Therefore, the
center frequency stability of the discriminator does
not effect the operation of the afc system.
The l ast stage of the error signal amplifiers, Q507,
is a phase splitter to provide a push-pull output to
the synchronous detector. The synchronous detector
10
STEAM POWERED RADIO.COM

is keyed by the 5-cps square-wave keying signal from
the keying generator.
The synchronous detector recovers the information
contained in the amplitude and phase of the 5-cps error
signal. The circuit used in the A830-2 is actually two
synchronous detectors operating from opposite half
cycles of the 5-cps square-wave keying signal so that
the 5-cps square-wave keying signal is balanced outin
the output. This is analogous to a double-sideband
balanced modulator in which neither input signal is
present in the output.
Figures 2-3 through 2-5 illustrate the operationofthe
two diode switches and the synchronous detector. The
electronic circuit and a mechanical analog for each
of the circuits is shown. The resistances marked
Rf represent the forward resistance of the diodes.
The output of the synchronous detector may be disabled
for test and adjustment by depressing AFC DISABLE
switch S102 on the front panel.
2.3.3 POWER AMPLIFIER.
The 14-mc FM signal from the modulator is coupled
to a balanced mixer, V427. The other input to V427
is the amplified output of a vhf crystal oscillator,
V426A. The crystal oscillator operates with a fifthovertone series- resonant crystal in the 74- to 94-mc
frequency range.
The specific frequency of the
crystal is 14 me below the station's assigned output
frequency. The exact frequency is adjustable over
a small range by VHF OSC FREQ ADJ control C427.
This adjustment is required to compensate for the
finishing tolerance and aging in crystals Y426 and
Y501. The output of V426A is amplified in V426B
and coupled to V427.
The two input signals are
balanced out of the output of V427 and the sum of the
two signals is the operating frequency . The MIX
BAL control compensates for unbalance between the
sections of V427.
The output of V427 is coupled to limiter amplifier
V428. The limiter amplifier removes any amplitude
modulation resulting from mixing and couples this
signal to driver stage V429. The signal is amplified
by V429 to a level sufficient to drive power amplifier
stage V430. The power output is adjustable with
POWER OUT control R454. The tuning and loading of
the output stage is accomplished with C461 and C456.
2.3.4 POWER SUPPLY.

The power supply in the A830-2 provides all operating
voltages for the A830-2 and 786M-1 Stereo Generator,
if used. The primary power may be 115 or 230 volts,
60 cps. The power supply is of conventional design
using a bridge rectifier and a voltage divider for the
high voltages. The low voltages are obtained from
full-wave rectifiers. Voltage breakdown diodes are
used for regulating the +20-volt, +10-volt, and -10volt outputs to ±5 percent.

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

NOTES '.

LEFT
AUDIO
OUT

MONOPHON IC 0 R
LEFT
AUDIO
IN

-

MONOPHONIC
AUDIO
OUT

,,

I . ZIOI IS CONNECTED IN SERIES WITH FLI02 AND J604 WHEN THE A830-2 IS
USED IN MONOPHONIC SERVICE . ZIOI IS NOT USED IN STEREOPHONIC SERVICE .
2 . THE EXACT FREQUENCY OF Y426 IS 14 MEGACYCLES BELOW THE
ASSIGNED FREQUENCY OF OPERATION .
LOW -

PRE-EMPHASIS
FLIOI

-

PASS
FILTER
FLI02

f------4,

(SEE NOTE I)

808 AUDIO
PAD

VHF
OSCILLATOR
V426A

ZIOI
\,

BUFFER
V426B

~•J

~
AUDIO FEEDBACK

---

OSCILLATOR

-

BALANCED

MIXER

,-.,-----4

V427

LIMITER
AMPL
V428

-

DRIVER

V429

-

POWER

OUTPUT
88-l08MC
IOWATTS

AMPL
V430

Y426
74-94MC
SEE NOTE 2

MODULATOR

DISCRIMINATOR
. - -'-

-

SCA INPUT

BASEBAND
INPUT

>-.....

FIRST

BASEBAND
AMPL
Q607

./

-

SECOND
BASEBAND

AMPL
Q608

-

FREQUENCY
MODULATED
OSCILLATOR
Q60I

-

FIRST
LIMITER
Q602

-

SECOND
LIMITER
0603

i-----

DISCRIMINATOR
DRIVER
Q604

-

r,

OUTPUT
AMPL
Q606

r

l

I

AFC
BUFFER
Q605

AFC CORRECTION

~ EYI NG

GENERATOR
0 5 08
6 .3V A C -

SYNCHRONOUS
DETECTOR

-

ERROR
SIGNAL

AFC
DISCRIMINATOR

AMPLIFIERS
Q504-0507

BASEBAND
CANCEL
AMPL
0511

f------.

-

DISCRIMINATOR
DRIVER
i---Q503

-

SECOND
LIMITER
0502

I

DIODE
SWITCH
CR51I

FIRST
LIMITER .

Q50I

i----

DIODE
SWITCH
CR50I
CR502

i----

l4MC
REFERENCE
OSCILLATOR
0512

l

•

VIBRATOR

•

MULTI-

MU LT I-

i- ~

Q5 10

VIBRATOR
0!109

t 350V DC ___,__
t300V D C +l80V, 'DC ~

,.

POWER
SUPPLY

+20V DC REGULATED -

~•J

tlOV DC REGULATED -IOV DC REGULATED -

Y50I
14MC

'

'
1,

'
STEAM POWERED RADIO.COM

Figure 2-2. A830-2 10 W Wide-Band FM
Broadcast Exciter, Block Diagram
11
i

;,:,

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

MODULATED CARRIER

...•r",,.

ACTUAL CIRCUIT

REFERENCE SIGNAL

-

----1--------------"

-------------------------------------------M~ULATEO CARRIER
\

Rt
REFERENCE SIGNAL -------11----~V0,-----<0

MECHANICAL ANALOG

Figure 2-3. Reference Switch, Simplified Schematic and Mechanical Analog Diagram

STEAM POWERED RADIO.COM

12

-

TD-536
A830- 2 10 W Wide-Band FM Broadcast Exciter

BASEBAND INPUT

ACTUAL CIRCUIT

BASEBAND INPUT

,~----- - - < ~

BASEBAND D UT PUT

MECHANICAL ANALOG

Figure 2-4. Baseband Cancel Switch, Simplified Schematic and Mechanical Analog Diagram

13
STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

DC OUT
KEY 1--------e

ACTUAL CIRCUIT

DC OUT

ERROR
SIGNAL

-

MECHANICAL ANALOG

Figure 2-5. Synchronous Detector, Simplified Schematic and Mechanical Analog Diagram

14
STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

SECTION Ill
MAINTENANCE
3. 1 GENERAL.

This section contains alignment instructions , adjustment procedures, and minimum performance standards for the A830-2.
3.2 TEST EQUIPMENT REQUIRED.

The test equipment in table 3-1, or its equivalent, is
required to perform the procedures given in this
section.
TABLE 3-1
TEST EQUIPMENT REQUIRED

ITEM
Audio oscillator

MANUFACTURER'S
DESIGNATION
Hewlett-Packard 200AB

Distortion and noise meter Hewlett-Packard 330D
A-c vtvm

Hewlett-Packard 410B

R- f vtvm*

Bird 91C

Communications receiver

Capable of receiving
14 me

10-db pad

Microlab AD-l0N

Oscilloscope
FM monitor

Hewlett-Packard 335B

50-ohm load
*The 91C is not required if a Tektronix 541 oscilloscope is available. See paragraph 3.3.10.

c. Connect the 50-ohm load to RF OUTPUT jack
J402.
d. Operate POWER switch S401 to the ON position.
Allow 10 minutes for equipment warm up.
3.3.Z MODULATOR LIMITER-DISCRIMINATOR
ALIGN1'4ENT.
a. Remove Q601 from its socket.
b. Rotate
REF
LEVEL
control R572 fully
counte rclockwise.
c. Connect a 0.01-uf capacitor and clip lead between
the movable arm of REF LEVEL control R572 and the
emitter pin on the socket for Q601. This supplies an
accurate 14-mc signal for alignment of the A830-2.
d . Connect the HP-410B to TP602 and set it to the
lowest d-c s c ale.
e. Rofate R572 clockwise until an indication is
observed on the HP-410B.
NOTE
During this adjustment, maintain the 14-mc
signal at a level below limiting. Limiting
cause s the tuning peaks to be very broad.

f. Adjust C639, L606, and L603 for maximum
indication on the HP - 410B.
g. Remove the 0.01-uf capacitor and clip lead from
XQ601 and R572, Replace Q601 into XQ601.
h. Connect the 91C to TP504.
NOTE
Refer to note in paragraph 3.3.10.

3.3 ALIGNMENT AND ADJUSTMENT.

Do not make any adjustme nt in the modulator
or automatic frequency control sections of the
A830-,2 unless trouble has definitely been
traced to misadjustment.

i. Remove Q509 from its socket.
j. Adjust R572 for an indication of 30 millivolts,
k. Replace Q509.
3 .3.3 MODULATOR OUTPUT AMPLIFIER TUNING.
a. Set the meter selector switch on the front panel
of the A830-2 to the MOD OUTPUT B position.
b . Tune L611 for maximum indication on the front
panel meter.

3.3.1 PRELIMINARY ADJUSTMENTS.

3.3.4 AFC BUFFER TUNING.

Perform the following procedure prior to performing
any of the alignment procedures .

a. Connect the 91C (or Tektronix oscilloscope) to
TP504.
b. Remove Q510 from its socket.
c. Tune L608 for maximum indication on the 91C
(or oscilloscope).
d. Replace Q510 into its socket.

a. Set the meter switch on the A830- 2 to the OFF
position.
b . Short AFC DISABLE switch S102 on the A830-2
with a clip lead.

15
STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter
3.3.5 FM OSCILLATOR ADJUSTMENT.
a. Loosely couple the communications receiver to
FM oscillator Q601 and to the 14-mc reference
oscillator. If the receiver has a bfo, turn it off.
b. Adjust OSC FREQ control C606 for a zero beat
on the communication receiver.
c. Remove the communications receiver.

IMPROPER ADJUSTMENT

3.3.6 MODULATION DISCRIMINATOR.
a. Connect the HP-410B to TP601.
b. Adjust DISCR SEC control C644 for a zero indication on the HP-410B.
c. Check adjustment of DISCR PRI control C639.
It should be set for a maximum indication, and C644
set for a minimum indication.
3.3.7 AMPLIFIER BIAS ADJUSTMENT.
PROPER ADJUSTMENT

a . Connect the HP-410B to TP603.
b. Adjust R641 for an indication of +7.5 volts d-c.
3.3.8 MODULATOR GAIN ADJUSTMENT.
a. Remove the 50-ohms load and connect the HP-335B
to the output of the A830-2 through the 10-db pad.
b. Connect the HP-200AB to baseband input jackJ604,
c. Set the output level of the HP-200AB to 0.1
volt rms at 1000 cps.
d. AdjustMODGAINcontrolR635 for an indicationof
100 percent modulation (±75-kc deviation) on the
HP-335B.
3.3.9 AFC LIMITER-DISCRIMINATOR ALIGNMENT.
a. Connect the HP-410B to TP501 and set to 10-volt
scale.
b. Remove Q509 from its socket.
c. Adjust
REF
LEVEL control R572 fully
counterclockwise.
d. Adjust L504, L505, and C515 (DISCR PRI control)
for maximum indication on the HP-410B.
e . Connect the 91C to TP504.
f. Adjust R572 for an indication of 30 millivolts
on the 91C.
g. Connect the HP-410B to TP502 and adjust DISCR
SEC control C518 for a minimum indication on the
HP-410B when set to its lowest range.
h. Replace Q509 in its socket.
i. Reset R572 as specified in paragraph 3.3.10.
3.3 .10 REFERENCE LEVEL ADJUSTMENT.

NOTE
The following procedure may be accomplished
with the 91C or with a Tektronix 541 oscilloscope. Steps a through f describe the procedure for using the 91C and steps g and h
describe the procedure for using the 541
oscilloscope .
16
STEAM POWERED RADIO.COM

Figure 3-1. Reference Level
Adjustment, Oscilloscope
Patterns

a. Connect the 91C to TP504.
b. Remove Q510 from its socket.
c. Tune L608 for maximum indication on the 91C.
Record the reading on the 91C.
d. Replace Q510 and remove Q509 from its socket.
e. Adjust R572 for the same indication recorded
in step c.
f. Replace Q509 in its socket.
g. Connect the Tektronix oscilloscope to TP504.
h. Adjust R572 for alignment of base lines of alternate signals. See figure 3-1.
i. Set meter switch S101 on the A830-2 front panel
to the 14 MC REF B position. The meter should
indicate in the B range.
3.3.11 BASEBAND CANCELING ADJUSTMENT.
a. Remove Q510 from its socket.
b. Make certain that AFC DISABLE switch Sl02 is
still jumpered.
c. Rotate R562 to its maximum counterclockwise
position.
d. Connect the oscilloscope to TP503.
e . Connect the HP-200AB to baseband input jack
J604.
f. Set the HP-200AB to 50 cps.
g. Set the level of the HP-200AB to produce a 2-volt
peak-to-peak waveform on the oscilloscope.
h. Adjust the oscilloscope to display the 50-cps
waveform.
i. Slowly adjust R562 to cancel the signal on the
oscilloscope. Gradually increase the input signal
from the HP-200AB to 0.1 volt while maintaining the
null by adjustment of R562. The waveform on the
oscilloscope should be less than 1 volt peak-to-peak
when the input signal is 0.1 volt.
j. Replace Q510.

I

TD- 536
A830- 2 10 W Wide- Band FM Broadca st Exciter
3.3.12 AFC LOOP CHECK.

3.4.3 HARMONIC DISTORT ION.

a. Remove the jumper from across AFC DISABLE
SWITCH Sl02.
b. Observe the deviation meter on the HP- 335B
and depress the AFC DISABLE switch. The fre quency should slowly drift off and come back quickly
when the AFC DISABLE switch is released .

the prelimin ary procedu res of
a. Perform
paragrap h 3.4.1.
b. Set the HP- 200B frequenc y to 50 cps and the
Measure the harmoni c
output level to 0.01 volt.
It should be 1.0 per330D.
HP
distortio n on the
cent or less.
step b for frequenc ies of 400 and
c. Repeat
15,000 cps.

3.3.13 POWER AMPLIF IER ADJUSTM ENT AND
TUNING .
a. Set meter switch SlOl on the A830- 2 to the
MIXER GRID A position.
b. Adjust C431 for maximum indicatio n on front
panel meter Ml0 l.
c. Adjust VHF OSC FREQ ADJ control C427 so that
the HP- 335B indicates on frequenc y.
d. Switch Sl0l to BUFFER GRID A and observe
It should indicate approxim ately 1 unit.
meter.
Sl0l to V428 B.
Switch
e.
f. Adjust L429, L430, and MIX BAL control R438
for maximum indicatio n on the front panel meter.
g. Switch Sl0l to V429 B.
h. Adjust L431 and L432 for maximum indicatio n
on the front panel meter.
i. Remove all connecti ons to J402 and connect the
50-ohm load to J402.
j. Connect the HP-410B across the 50- ohm load.
k. Switch Sl0l to V430C B.
l. Adjust PA PLATE control C461 for minimum
indicatio n on the front panel.
m. Adjust PA MATCH control C456 for a maximum
indicatio n on the HP - 410B.
n. Adjust POWER OUT control R454 for an indicatio n
of 22.5 volts.
3.4 MINIMUM PERFOR MANCE STANDA RDS.
The A830-2 should be tested in accordan ce with the
follow ing procedur es after alignmen t and adjustme nt.
The following tests may be used to determin e if the
A830 - 2 is operating properly .
3.4 .1 PRELIMI NARY ADJUSTM ENTS.
a. Connect the HP-200A B to J604 on the A830- 2.
b. Connect the HP - 335B through the 10- db pad to
J402.
c. Connect the HP-330D to the modulati on output of
the HP- 335B.
3.4.2 FREQUE NCY RESPON SE.
the prelimin ary procedur es of
a . Perform
paragrap h 3.4.1.
b . Set the HP- 200AB for an output of 0.100 volt
on a fr equency of 400 cps.
c. Adjust the HP- 330D for an indicatio n of 0 db.
d. Set the HP-200A B to 50 cps and reset output level
The HP - 330D indicatio n should be
to 0 .100 volt.

0 ±0.3 db.

e. Repeat s tep dforafre quencys ettingof 15,000 cps.

3.4.4 RESIDUA L FM NOISE.
prelimin ary procedur es of
the
a. Perform
paragrap h 3.4.1.
b. Set the HP - 200AB to 400 cps at an output level
of 0.100 volt.
c. Measure the level across terminal s 1 and 2 of
the HP- 335B with the HP - 330D. Record the reading.
d. Turn off the HP-200A B and record the indicatio n
on the HP - 330D. Record this reading.
e. Compute the s+n/ n ratio using the readings
recorded in steps c and d. The ratio should not be
less than 60 db.
3.4.5 CARRIE R FREQUE NCY SHIFT.
prelimin ary procedur es of
the
a. Perform
paragrap h 3.4.1.
b. Remove the audio input from J604.
c . Connect the output of the HP- 200AB to terminal s
3 and 4 of TBl0l.
d . Adjust the output of the HP - 200AB to a frequenc y
of 1000 cps and to a level sufficien t to modulate the
carrier 100 percent.
e. Remove the audio connectio ns from terminal s
3 and 4.
f. Adjust the HP - 335B to indicate 0 frequenc y
deviation .
g. Touch the audio connectio ns from the HP-200A B
to terminal s 3 and 4 of TBlOl and note the carrier
It should be less than
deviation on the HP-335B .
500 cps.
3.4.6 AM NOISE MEASUR EMENT.
the prelimin ary procedur es of
a. Perform
paragrap h 3.4.1.
b. Set the HP-335B function switch to CARRIE R
LEVEL and read the carrier output voltage on the
An indicatio n of 100 percent
modulati on meter.
modulati on equals 10 volts, 90 percent modulati on
equals 9 volts, etc.
c. Connect the 91C to J3 on t he HP - 335B and
measure the noise output. Compute the carrier- toAM noise ratio using the following formula:
Carrier Voltage
Carrier
20
loglO AM Noise Voltage
AM Noise =
The ratio should not be less than 50 db.
17

STEAM POWERED RADIO.COM

TD-536
A830-2 10 W Wide-Band FM Broadcast Exciter

SECTION IV
PARTS LIST
ITEM

I

' COLLINS
IPART NUMBER
I

DESCRIPTION

A830-2 10 W WIDE- BAND FM BROADCAST EXCITER

549-1588-00

PANEL

FLI0l

ATTENUATOR, FIXED: pre-emphasis network for

458-0650-00

745- 1352- 00

C451
C452

use in FM commercial broadcast equipment;
600 ohms balanced, w/ center tap; ±1 to :t:1.5 db

frequency response
FLI02

MIO!

RIO!
Rl02
Rl03
Rl04
S!Ol

673- 0869-00

FILTER, HIGH PASS: metal encased, herme tically
sealed, i nput 600 ohms, output 600 ohms, 4 solder
type terminals; continuous duty cycle; A. D. C .
part no. D10390
METER, ARBITRARY SCALE: permanent magnet
moving coil d- c microamme ter, 500 ua, 100 ohms
resistance; 2 scales, A scale, 10-90 ua, B scale,
175-500 ua; Assembly Products, Inc. part no. 361
RESISTOR, FIXED, COMPOSITION: 1000 ohms
±10%, 1/ 2 w
RESISTOR, F IXED, FILM: 562 ohms ±1%, 1/ 4 w
RESISTOR, FIXED, FILM: 261 ohms ±1%, 1/ 4 w
RESISTOR, FIXED, FILM: same as RI03
SWITCH, ROTARY: 2 circuit, 2· pole, 10 position,

2 section; 2 moving, 22 fixed contacts
SWITCH, PUSH: spst; momentary; 125 v a - c,
0 .75 amp, 250 v a- c, 0.25 ampj Cutler-Hammer
part no. 8411-KG
T BI0l TERMINAL BOARD: barrier type w/ double row
front connection of 12 screw terminals; 13/ 32 in.
by 7/ 8 in. by 5-11/ 64 in.; Howard B. Jones , Div.
Cinch Mfg. Co. part no. 12-140-D
T B102 TERMINAL BOARD: Bakelite, 4 te1·minals, I
grounded, 3 insulated; 21 / 32 in, w by 1-1/ 2 in.
lg; Cinch Mfg. Corp, part no. 1534-A
XFLI0I SOCKET, E LECTRON T UBE: 8 prong octal tube
socket w/ steel mtg plate; Amphenol-Borg
Electronics part no. 88-STM

705-7084-00
705-7068- 00
705-7068-00
259-1567-00

SI02

266-6169-00
367-0518-00

306-2240-00

220-1005-00

I

POWER AMPLIFIER AND POWER SUPPLY

C401
C402
thru
C408
C409
A&B
C410
C411
C412
C413
C414
lhru
C425
C426
C427
C428
C429

C430
C431
C432

CAPACITOR, FIXED, CERAMIC: 1000 uuf ±20%,
500 vdcw
CAPACITOR, FIXED, CERAMIC: same as C401

C433
C434
C435
C436
C437
C438
C439
tl1ru
C444
C445
C446
thru
C449
C450

379- 0426- 00

913-1 186- 00
913- 1186- 00

CAPACITOR, FIXED, ELECTROLYTIC: dual
section, 40 uf ea section; -10% +~0%, 450 vdcw;
Sprague Electric part no. Y27674
CAPACITOR, FIXED, ELECTROLYTIC: 1000 uf
- 10% +100%, 50 vdcw
CAPACITOR, FIXED, ELECTROLYTIC: same
as C410
CAPACITOR, FIXED, ELECTROLYTIC: 500 uf
- 10% +100%, 50 vdcw
CAPACITOR, FIXED, ELECTROLYTIC: 4 uf -10%
+100%, 50 vdcw
NOT USED

183 - 1259-00

CAPACITOR, FIXED, MICA: 5 uuf ±5%, 500 vdcw;
Electro Motive part no. DMl 5C050J01
CAPACITOR. VARlABLE, CERAMIC : 3.0 uuf min
to 12.0 uuf max, 350 vdcw
CAPACITOR, FIXED, MICA: 470 uuf ±5%, 300
vdcw; Electro Motive part no. DM15F471J01
CAPACITOR, FIXED, CERAMIC: 1.5 uuf ±5%,
500 vdcw; StackpQle Carbon Co. part no.
GA- 1. 5uuf PORM5
CAPACITOR, FIXED, CERAMIC: 4700 uuf ±20%,
500 vdcw
CAPACITOR, VARIABLE, AIR: 3.0-9.8 uuf,
1250 vdcw; E. F . Johnson part no. 160- 211
CAPACITOR, FIXED, CERAMIC: 7.5 uur ±5%,
500 vdcw; Stackpole Carbon Co. part no.
GA- 7. 5uuf PORM5

912-2750-00

183-1403- 00
183- 1403- 00
183- 1575-00
183-1389- 00

C453
C454
C455
C456
C457
C458
C459
C460
C461

C462
C463
C464
C465
thru
C468
C469
C470
C471
thru
C474
C475
thru
C480
C481
C482
C483
C484
C485
C486
C487
C488
C489
C490
C491
CR401

18

STEAM POWERED RADIO.COM

917- 1072-00
912- 2864- 00
913-2981-00
9 13- 1187- 00
922- 0046- 00
913-2997-00

DESCRIPTION

ITEM

CR402
thru
CR408
CR409

CR410
CR411
A&B
CR412

COLLINS
P ART NUMBER

CAPACITOR, FIXED, MICA: same as C426
CAPACITOR, FIXED, MICA: same as C426
CAPACITOR, FIXED, CERAMIC: same as C430
CAPACITOR, FIXED, MICA: 10 uuf ±5%, 500 vdcw;
Electro Motive part no. DMl5C100J0I
CAPACITOR, FIXED, MICA: same as C436
CAPACITOR, FIXED, CERAMIC: same as C429
CAPACITOR, FIXED. CERAMIC: same as C430

912- 2774-00
912-2774-00
913-1187-00
912-2753- 00

CAPACITOR, FIXED, CERAMIC: same as C429
CAPACITOR, FIXED, CERAMIC: same as C430

9 13-2981-00
913- 1187-00

CAPACITOR, FIXED, CERAMIC: 1000 uuf -20%
+80%, 500 vdcw; Erie Resistor part no.
327-029X5T0I02Z
CAPACITOR, FIXED, CERAMIC : same as C429
CAPACITOR, FIXED, MICA: 33 uuf ±5%, 500 vdcw;
Electro Motive part no. DMl5E330J0I
CAPACITOR, FIXED, CERAMIC : same as C430
CAPACITOR, FIXED, CERAMIC : same as C430
CAPACITOR, FIXED, CERAMIC: same as C430
CAPACITOR, VARIABLE, CERAMIC: 4 .5 uuf
min to 25 uuf max, 500 vdcw
CAPACITOR, FIXED, CERAMIC: same as C450
CAPACITOR, FIXED, CERAMIC: same as C450
CAPACITOR, FIXED, CERAMIC: same as C450
CAPACITOR, FIXED, CERAMIC: same as C430
CAPACITOR, VARIABLE, AIR: 3.0 uur min to
18. 7 uuf max; 1250 v a-c; E. F. Johnson Co.
part no. 160-110-3
CAPACITOR, FIXED, CERAMIC: same as C450
CAPACITOR, FIXED, CERAMIC: same as C450
CAPACITOR, FIXED, MICA: same as C428
CAPACITOR, FIXED, CERAMIC: same as C430

9 13-1 292 - 00

913- 1292- 00
913-1292- 00
912- 2864- 00
913-1187-00

NOT USED
NOT USED
CAPACITOR, FIXED, CERAMIC: same as C430

913- 1187- 00

CAPACITOR, FIXED, CERAMIC: same as C450

913-1292-00

CAPACITOR, FIXED, CERAMIC: 1.0 uuf ±5%, 500
vdcw; Stackpole Carbon Co. part no.
GA-l.0uufPORM5
CAPACITOR, FIXED, MICA: same as C428
CAPACITOR, FIXED, MICA: same as C428
CAPACITOR, FIXED, MICA: same as C428
CAPACITOR, FIXED, CERAMIC: same as C450
CAPACITOR, FIXED, MICA: same as C426
CAPACITOR, FIXED, MICA: same as C426
CAPACITOR, FIXED, MICA: same as C426
CAPACITOR, FIXED, MICA: 150 uuf ±5%, 500
vdcw; Electro Motive part no. DM15Fl51J01
CAPACITOR, FIXED. MICA: same as C489
CAPACITOR, FIXED, MICA: 20 uuf ±5%, 500 vdcw·
Electro Motive pa1·t no. DMl5C200J01
'
SEMICONDUCTOR DEVICE, DIODE : Silicon;
Motorola part no. 1Nl492
SEMICONDUCTOR DEVICE, DIODE: same as
CR401

9 13-2977-00

SEMICONDUCTOR DEVICE , DIODE: s ilicon,
singl e phase, half-wave; General Electric part
no. 1N538
SEMICONDUCTOR DEVICE, DIODE: same as
CR409
SEMICONDUCTOR DEVICE, SET: two hermetically
sealed silicon voltage reference diodes:
Motorola part no. IOMI 0ZBl
SEMICONDUCTOR DEVICE, DIODE: silicon,

353-1526-00

hermetically sealed; International Rect. Corp

part no. 1 ZI 0V0l

912-2753-00
913-2981-00
913- 1.187- 00

913- 2981-00
912-2780-00
913-1187-00
913-1187 - 00
913- 1187- 00
917-1026-00
913-1292- 00
913-1292-00
913- 1292- 00
913- 1187- 00
922-0033-00

912-2864-00
912-2864-00
912-2864- 00
913-1292-00
912-2750-00
912-2750-00
912-2750- 00
912-2828-00
912-2828-00
912- 2765-00
353-1661 -00
353-1661 -00

353-1526-00
353-1238-00

353- 1208- 00

TD- 536
A830-2 10 W Wide- Band FM Broadcast E xciter

DESCRIPTION

ITEM

CR413
CR414
CR415
CR416

COLLINS
PART NUMBER

ITEM

SEMICONDUCTOR DEVICE, DIODE : same as
CR409
SEMICONDUCTOR DEVICE, DIODE: same as
CR409
SEMICONDUCTOR DEVICE , DIODE: same a s
CR412
NOT USED

353-1 526- 00

R426

353-1 526- 00

R427

353- 1208-00

R428

SEMICONDUCTOR DEVICE, DIODE: silicon,
hermetically sealed, diffused-junction type;
Motorola part no. 1N977A
FUSE, CARTRIDGE: 1.00 amp current rating,
250 v, glass body, ferrule terminals; Bussmann
part no. MDL 1
FUSE. CARTRIDGE: 0.250 amp current r ating.
250 v d -c , glass body, ferrule terminals
JACK, TELEPHONE: steel. miniature, panel mtg;
Switchcraft, Inc. part no. 3501FP
CONNECTOR, RECEPTACLE, ELECTRICAL:
single round female contact, right angle shape;
Amphenol part no. 31- 213
REACTOR: 7.2 henrys m in. 0.300 amp d- c; 60
ohms; 4-37 / 64 in. by 5-5/16 in. overall; Stancor
Elec. Inc. part no. RS-8300
NOT USED

353-3237-00

COIL, RADIO FREQUENCY: 0.68 uh ±3%, 250 me,
0. 12 ohm, 1750 ma; 3/ 16 in. dia by 7/16 in, lg;
Delevan part no. 1840
COIL, RADIO FREQUENCY: 0 .25 uh ±3%. 400 me,
0.04 ohm, 2850 ma; 3/ 16 in. dia by 7/ 16 in. lg
COIL, RADIO FREQU!;;NCY, NO. 1: single layer
wound #14 wire, 1/ 2 in. ID of con, 7/ 8 in. lg
overall
COIL, RADIO FREQUENCY: va riable; 88 to 106
me, +l 5°C to +55°C temp range; 850 v d- c
dielectric strength
COIL, RJ\DIO FREQUENCY: same as L429

240- 1844-00

R429

thru

CR425
CR426

F401

F 402
J401
J402

L401

L402

R430
R431
264- 4280-00

R433
264-4240-00
360-0148-00
357- 9258-00

668-0015-00

L427
L428

L429

L430

L436

L437
L438

L439

L440

L441
R401
R402
R403
R404
R405
R406
R407
R408

R411
R412
R413
R414
thru
R425

R440
R441
R442
R443
R444
R445

549- 1605-003

278- 0730- 00

R446
R447
R448
R449

278-0730-00
R450

COIL, RADIO FREQUENCY, NO. 2: single l ayer
wound #16 wire; 3/ 4 in. ID of coil, 2-7/ 8 in. lg
overall
COIL, RADIO FREQUE NCY: s i ngle layer wound;
5.6 uh, 860 ma current. 0.95 ohm; Jeffers
El ectronics Div. of Speer Carbon Co. part no.
10402-34
COIL, RADIO FREQUENCY: same as L436
COIL, RADIO FREQUENCY: single layer wound,
0.47 uh nom inductance, 0.09 ohm max de
resistance, 1600 ma max current rating; Jeffers
Electronics. Div. of Speer Carbon Co. part no .
10100- 126
COIL, RADIO FREQUENCY, NO. 3 : single layer
wound #1 4 wire, 3/ 4 in. ID of coil, 1-3/ 8 in. h;
approx 1-11/ 16 in. lg overall
COIL, RADIO FREQUENCY: 1.00 uh ;JO%, 0. 30
ohm d-c resistance; 850 ma d-c; Jeffers
Electronics part no. 10100-128
COIL, RADIO FREQUENCY, NO. 4: single layer
wound #18 wire, 3/16 in. ID of coil, 5/ 16 in. lg
-RESISTOR, FIXED, WIREWOUND: 100 ohms
±HJ%, 10 w
.RESISTOR, FIXED, WIREWOUND: 16,000 ohms
±5%, 25 w
NOT USED
RESISTOR, FIXED, WIREWOUND: 600 ohms
±10%, 10 w
RESISTOR, FIXED, WIREWOUND: 12,000 ohms
±10%, 10 w
RESISTOR, FIXED, WIREWOUND: 25,000 ohms
±10%, 10 w
RESISTOR, FIXED, WIREWOUND: 5. 0 ohms
±10%, 5 w
RESISTOR, FIXED, WIREWOUND: 25 ohms
±:10%, 7 w

R409
R410

R435
R436
R437
R438

240-1843- 00

thru

L434
L435

R434

R439

thru

L425
L426

R432

·RESISTOR,
RESISTOR,
±5%, 5 w
RESISTOR,
RESISTOR,
RESISTOR,
±10%, 7 w
NOT USED

549-1606-003

R451
R452

240- 0179-00
R453
R454
240-0179- 00
240-0060-00

R455
R456
R457

549-1607- 003

240-0062-00
553-5671- 002
710-9053- 00

R458
R459
R460
R461
R462
R463
R464
R465

7 10- 0369-00
R466
710-9081-00

R467

710- 9070-00

S401

710- 9068-00
T401
710-9105-00
710-9019- 00
T402

FIXED, WIREWOUND: same as R408
FIXED, COMPOSITION: 160. 0 ohms

710-9019- 00
747- 5444-00

FIXED, COMPOSITION: same asR407
FIXED, COMPOSITION: s ame as R410
FIXED, WIREWOUND: 100 ohms

710-9105-00
747 - 5444- 00
710-9005- 00

T403
thru
T425

DESCRIPTION

COLLINS
PART NUMBER

RESISTOR, FIXED, COMPOSITION: 10,000 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMP OSITION: 1000 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 220 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 2700 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 47,000 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 1500 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 39,000 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 2200 ohms
;JO%. 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 0.10 megohm
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: s ame as R434
RESISTOR, FIXED, COMPOSITION: same as R431
RESISTOR, FIXED, COMPOSITION: same as R433
RESISTOR. VARIABLE: COMPOSITION; 500
ohms ±20%_. 0. 2 w
RESISTOR, FIXED, COMPOSITION: 3300 ohms
±10%, 2 w
RESISTOR, FIXED, COMPOSITION: same as R439
RESISTOR, FIXED, COMPOSITION: same as R434
RESISTOR, FIXED, COMPOSITION: same as R426
RESISTOR, FIXED, COMPOSITION: 68 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 39,000 ohms
±10%, I w
RESISTOR, FIXED, COMPOSITION: 4700 ohms
±10%, 1 w
RESISTOR, FIXED, COMPOSITION: same as R434
RESISTOR, FIXED, COMPOSITION: same as R426
RESISTOR, FIXED, COMPOSTJON: 270 ohms
±10%, I w
RESISTOR, FIXED, COMPOSITION: 10,000 ohms
±10%, 1 w
RESISTOR, FIXED, COMPOSITION : 820 ohms
±10%, 2 w
RESISTOR, FIXED, COMPOSITION: 10 ohms
±10%, 1/2 w
RE.S ISTOR, FIXED, COMPOSITION: 3300 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: same a s R432
RESISTOR, VARIABLE, WIREWOUND: 250 ohms
±10%. 2 w
RESISTOR, FIXED, COMPOSITION: 180 ohms
±10%, 2 w
RESISTOR, FIXED, COMPOSITION: 8200 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION: 33 ohms
±10%, 1/ 2 w
RESISTOR, F IXED, COMPOSITION: 100 ohms
±10%, 1/ 2 w
RESISTOR, FIXED, COMP ArTl>.CHEO. REMO',/[ JuMe,A
FRet, '8101 • 7 TO TO IOl-12 AN~ CONNEC T
JUMPER FROM TB IOl -0 to n ,0 1- 11,

-7

FL I 01

4 ,-, I i ~

::
.:;Hs,;,,IO
+--<','>------ -+','cOc

0

•

,----

'"

11 10 1

RIOZ

;rfr1-

---..:-1r021

:: :
G I '

~ - ~•

-

>

I

:t '---. --"

UNL•"
VALUEs
... I N
ME I N

c• m•u>

i

,..,

I:,---i
I

TPM2,

I

"" "

Ls••

,

'"

• •;
::

c,~~~= / '

1··

C64'
20

r •, ,7

1

'~j6"

C64?

·l•.,c• s,c l
,

TOOi

'"'""

" -

~.;~'

~

ca•o,

co40

,oo, ,,oo

J

·: I
" I

I

·-·
,..o

•u•
680

SECOND
BA5EBANQ

FIRST BASEBAND

"~
o•o>

1f

•••
'"'

I v

\h

...,

"'

-

c•o ,

"

C604 ~

SS40
5110

'"

,oo

""

hco~o

l '" '

1

,., II

'"

cso,

C60 >
O.O I UFl

I•""'- BIAS I

I

I

-

NOTE 2

1"·'"'

..,

LOIS

"50 1

C Sl2

"·'K I

.i

,oo

00 10

.i.k
I ""

ROOS

""'lr

IO K

"602

R60>

le.I K

26 10

~ ""'"~ """
IOK

· ~·~

I

--- ---

"'"'

I

r

~-l~')'°;':._.J.-00

79
"'
2 ISO

""'
J9 0K

l~~i~

R,',','

IEV 7:~~·

'"'"''

':"·":

"\

h

Q

~,:;: - I ~~!~,

".'a',

'

""

J.

1

Y42

IoWJ.

,R.~:~ ~~;1

"'

·'491

L 4>1

4

>R4JO

7.,

OU TPUT

I

c;,a

NOit

CO2'
O.OIUF

oso,

i

,•,a;

,o,·o,

R42'

c•Jo

', R42S

""'
,,uo

c•so1

" :g:~
lPS DI

~~:~

l,SIO!

';,~'g
~5:a"

I

~~~'

•: I
' I

I, > i

I

'1

' " ce s,s

I

L -i--- -

-

,,,

"""' ----

l u"

1_ "
i[cml

,c, 1 . ~.<'

a::-:,

"'"

~

,=rs•

ooo,
2 NTO•

I-

,,o I

Jc

r'

csso

"I

'2

U

"

g;~•-r ~~1'

:

c_;sr

0• 0•

,111-+---,<,:;".'\\
~1 10

,I

I

c01•
,oo

•

l K

CRS. 1

...~.

11 0

~

l..-

1

R06l

7 °"'' r,.''"'fu h:i_· ,g~~t,; .,..

O.OrnFJ:

-=~.-~~ ;:~~-~icooojl

=

"J..

de; - -

""'
10,
o,u,
l/ll2'5
~
-

c~;~~

C5C6

rOO lu<

"'<'------t======.____ ·-rc:c

I

coo,

rl

0,0IUFT

+

cooe
,o

I

, J,

,..-r

R"IO

e,001
4". 2

~

"°''
"""

[0-1)
Fa,c,
l ,I

ra~c4

~~;~-~ ~.:g;·~

1

J_o.muc

R5D2
2700

c,.,l as,o
•- '"'I- ""Q

1
a~'

.
so,"""} c-;o,

",o,

LJ__

1--

-

,t

•p:._
/

=

~

RISO

""o

-r'000U F

~

Re5 1

'4$0

40•0

.tig:~.

r -2700)
;:-

AUTOMATIC

F REQUENCY CONTROL

cc"
tO·OO

STEAM POWERED RADIO.COM

2'00

li

,.

270

'700

>4

T"
' ~ ""

soo -

'

470,JI

, _ __ _"_'_'~

""
'"'

R'76
SSC(l

-II cs•e

o .,sa,{"f

csc,,

' ·'

·--

1•00

CH> . IOOC

'""'"

'"~'•
IN02t

~~~· c,•x

""'

C4>l

""'

"'"'

C4W

HOO

cm
~-•

"'""

....

"~~.9

c~~•

- I

l"'- ..;TCHI

I

I

1oc<;
_J
- - - - - - ~ - -- ---~ --- ------ L . 1000
- - ~ - ~- - - -

,

iOOG

1

vmc

.... ::::=df~~:::::~..

SJOO

~po,:_

CeO
100<

I
I

I

1·

-,
d,

_j__

'""" 1 ..,
~~g~l} ~:g~~ \ ~
' ~n6 1)_ csaa
-

1000

I

L440

<'

••'"
"'

Co" J:
j_ uaso
I
C62'
:[_
-, ,":;>,- ----~--i",-__~---<"3-+------•-·•_•_'.:,___'-_•_·_'_'____ -J-______ _'____

AFC BUFFER

o.,ur

ISO

CRSIJ

-

,.,l csz,

C6LO

C••or
r

-,!,.

-

-

n o•

4 7 00

"'='"

A"IPL

I

r---,

r,so,

-

OS II

~)

,oo lf'

~

"'"
11 0

C,?2

1

BASEBANO CANCEL AMPl
2'117SA /

" "2

470

"

1

\:::-

I

RS5 1

2 ' 0
"
""
rnci,lJ :
- 'O.OIUF

""I
"""

' " '""

1oou:

7
0

=

=

"'i- -"•1:.'::

i..._

"\

0

210

•=
L--- - -- -~='-1-1-- -"

c 02 •

'" ' ""

..

CS •

"''';soo ?;:.

o,oo

QSOS

J

=

e,o

•

"" '
19SK

C4'J

-,-,a-,-.-.-,-""-.-, - --- --,-,-,-..-,-,-.-,..- - _\_____ ----- ---- ------.-,-,-- --- - - - - - - - - - - ~ --- --.-,-so-,-,,.-,-,-..-..--- --- -- ---

""'

coo,

"""

J:

RS,a
1'UO

•• ,,.

cs,s

---:::1

v11 r osc

r,'-"_'_'_ ___T___,_,':":':': _-,-----,---':':':': _,-- --..,~--'':":'c'_ _ ,,___'________ _ _____ _ ,':":':":'":::'":':',~::.~,,,,,,,- ------- - - - ------.,-T,-- ·'·":":':":.._,,_________c'c'c'°c':'c.:','": 'o"c'::._,_ _________:':':"'c';,u"'nR

'"'

'

I

lcs;o\.. ~
I"'
:J;."

"":'J:-

7

L•,~:: HER AM PLICIER

1' 01a

C42S

v

"'

j_
J:

c•••

±

0

0

IN2'0

L604

""
12
I 000

1 ;---~L~----,--------~~-------

4

o."'" '

O

A

t•Mo

"5J8

1

--,-,-so-,-.-.. ,-.-,-----,-,-so-,-s,s-,-.- -- -

ILGoa j

C62'1
o
.,u,J

S>Oa

U1SABLE1·1_

V'

DISCR
DR IVER

--r--,---,--+/---l
,

------- ~-- ----------- --- ---- ------ -- -- -------- ----·'--------- ---7
i
L __ ___ _
c...,:;:;::a-.
IAF' C

CR60S

co"

I

•<

-lee.a,

m

'Ca,

J..._

{

.,b. IH270

000!

_Io ,0 1u f

C 614

hl

,ou l'

R6l 4

CG'7

o.01u•1

--I!--·'",..·,,_'_,

coos
c.,u,

.

hes.,

_J.,,

coo•
$ - 25

.. ,.,,

I N l?O

I v

"""'
'"

'"""
"""' .,

i r+---± ., .,

SECOND l',"- ''-'s'- - - ~ - - -- ,-- S',,c'~

c••n,

2Nl>~6

cso,

CR601

••

..,

MOOUCATEO
OS OLLLATOR

cso,

R646
IO~K

, NI 71 I

ft6'4

~~- ~ ~- ~- s"c-

FIRS T LIM ITER

FREQUENCY
T P eo,

A"IPL

'/027'

I ,
<,o . '!"'••
•,1,:::'.;:JI
\~'U
'F,:••,------T---,,--'-"- 'f
~c~',4 c4',
,r '+-- -•-•• 6
~OWER
a•·1•
,-,ua•
'l
-,•""" ,
IBw"l
1-.',,\,'~'---.'i,\:'0
··~~-"EJ
'•,"~---- ----0a~;•:"_-T-•_;:u+-- I ,:·½o_,; L-',."••~c •
~·,-_,',',-"_'.,I'----''-i'·,~1-'i-'-r?"l':';:;rl,~ '", --~'"" ,--,,_~'"-rl,+--',':·',',1-~..,, ~ii ""'l-,----,-';:.,::"_,_-+=";'tC,-,J;\,-• ''---r
c:;•
,✓ !:\. :
i~s"
~::~/J{·:
i= ~.ti,'.••,. i ~."_;i,
,~
,~6'
c~~3
c,WJ.: = I
c•e2 ;: ,
--!_- ~•-·•_·_"_·•_._+---~
;:}~~ '~~•, L_,1,[;;(]af,J~,•L_I" ooc t=-t" •;o
~ c\""
J_e.9'\C ~;
±_Y~~ \_,IL4B I . l"jL4'41 ",~~• rn'_::X.:: '·•·• I'"'
I '1 ';,~~
,c
J_
la
s,
cs,a
c•a•
l
l
I,
•
~
~ - --1
s«e
•~~,j. '
.L
1
I ""
T
T
~
arcor ..
h
I
"2\',; I~~~
'""" f--- 1+~-r" •,~~~·.
I I II "'"
,u, i l :,, l eo
O.,S t .,, I - =
~~55
,.,,. ~
~j6~ I K~~ol ~ * C~H-:..~ ",;•,: - ~;;~ ~;;; l lc•ozl
~~!'
~'l~"~ r ~~~~ L
:~· I_';;• ~;~g-I. L,,T1I
I
1 ,. uo J.>uc•or* •100
V
I
~
I"""
I
•
•rn J
c•••
f12An L________
•••o ohcHo
•• .,
••oa ic ••2
a.. ,l c•••_l """
I
c••o ~
1
.r.
:r.
I
l
L "
L-----~~-+r"--,-_++_
_
_
_
_
_
_
-_-_-_-_-_-_-_-,~-------e-------------------•
;;gg
-~~,,,'
__
J.c_
_
_
-J-7~=~=~-l.----------"--~'----l-·,'
,
,b~
r•,
o
o
"·
'
,,
1•100
ft
,i;: I
I
t
_J_
' '
~
=
'·r ' ""'"

,.~.

C6 19

BALANC ED MIXER

I
I
I

..I.. C638

··-~

__ 1i - --------------f~~•~••~1_-.- ---- -------------------- ------------------ = =
1~-,.-,,------------ ------ ------71

I

R6SG

ae,o

,J

I
I
I

5 - 25

J o.o,u•

I
I
I

+-

· C6'9

C04•
S-1>

LOI<

7500

L

11045

-- ~

1

•

,so<

I

lS ABOV E SO MC.

0:' =
,- __ __"c'c'• •A•rn••"''•
,.PUT r ,

~
I

"""
l~ eo ,-,,.

100•

I

7

M ODULATOR

,._c--J::',:'_!'l.:1:::::;::::::;::;;;;;;;;;----~r:====-------------------l•••m~ I

•• • •

.I

, - -- -t--- -;
I c----- - - - - - - -- ~----

4. C4'6 IS NOT USEO WHEN CU.TPUf ·••uu£NCY

--- --- - - - - - - - - - - - ------ --- - - - - - - ----- -------- -- - - --

""

DISCR I IIIINATOR

V

OTHERWISE INDIC.O.UD ALL a,s,STANCe
ARE IN OHMS , U.F\OC lrANCE VAWU
PICOF>R>DS •No I NOLICTANC E 'JAcu,s
MICROHENRY$.

rI

-- ---

1

, _ fOK Sf£ R£0 u""RATION, TB IOO T ERMLNALS 3 . .o
4 ARE Ufl AU010 1Ne UT TCRNINA LS,

J600

- - -- - -

'

1

2 , SELEC TEC IN PROOUCTIOtl.
'

SECTION V
ILLUSTRATIONS

'

-

'

'.
1-- - - 1---Y.--lo •

'

IIS V,C

MCPS

••04

••

"•
•loOv

",~~1$

409

r----''

a,;o
• IO V

+___________c___ I

L____________

r i - - -- - - - - -- - - -- -+-----1I
'"C'f---- --r'-J'S"
:'s'~r,,;',,;_~:';";':"c___"'oe

CR4 12

t.l) ,;:~':.,,;;t"\

IZ IO>O• \-$"

1c::r

c"•' • ~:[',
IOM IOZa , 1, t )

160

"\'.'.~)

R40B

I

oou•J-

R•O>

-1

,I

c,10

.-1}.

·J:. 
0

0108
2N128~

~

e

Y101

.

0702

L701

~

2N1613

·o

~

0

•

0703

2N!285 I!)

•

•
~


0105
2H706

~

!"'115A

CARRIE/I
BALANCE

•
•

~
(!)

0
$

"
•
•

070&

(l)

I

\il)

a

0704

0

$

war

ZNl175A

•
0

$

0

--• .·.. =--1'
.· T ~
1, IIIIIJf

1,

R AUOIO

AEMOTE

L

tllPf

STEREO ON

OH

• •

58 KC Dft'VER:

ADD JOVU

7$ MIN

I,. AUDIO

M>O tOVU

STEREO-MON

KC t.KO

·

·

osc

75 IUH

Off

METER

CONTROL

LEVEL

L__PILOT__J
CARRIE/I

CHAN SEP
L•R AMPL

'"

Figure 1-1. 786M-1 Stereo Generator, Over-all View
3
STEAM POWERED RADIO.COM

TD-537
786M-1 Stereo Generator
contained within the 19-inch rack-mounted panel with
the exception of a left audio channel pre-emphasis
network. This function must be supplied externally and
is available in the Collins A830-2 l0WWide-Band FM
Broadcast Exciter.
Power input required is 20 ±0.1 volts d-c which is
supplied by the A830-2. Remote control can be exercised over the stereophonic and monophonic modes.
Power required for operation of remote control is 28
±2.8 volts d-c. Instruction books covering the exciter
and power amplifiers, used in conjunction with the
786M-1, are listed in table 1-1.

TABLE 1-3
EQUIPMENT REQUIRED BUT NOT SUPP LIED

COLLINS
PART NUMBER

EQUIPMENT

A830-2 10 W Wide- Band
FM Broadcast Exciter

522 - 2714- 00

1,6 ACCESSORY EQUIPMENT.

TABLE 1-1
ASSOCIATED EQUIPMENT INSTRUCTION BOOKS

ASSOCIATED
EQUIPMENT

INSTRUCTION BOOK
PART NUMBER

A830-2 10 W Wide- Band
FM Broadcast Exciter

TD- 536

B830-l 250- Watt FM
Power Amplifier

TD-538

D830- 1 1000-Watt FM
Power Amplifier

TD-567

E830-1 5-Kw FM
Power Amplifier

TD-539

Table 1-4 lists accessory equipment that is available
for use with 786M-1 Stereo Generator.

TABLE 1-4
ACCESSORY EQUIPMENT

EQUIPME NT

COLLINS
PART NUMBER

B830- 1 250-Watt
FM Power Amplifier

549- 2008-00

D830-1 1000-Watt
FM Power Amplifier

522- 2948-00

E830-l 5-Kw
FM Power Amplifier

549-2009-00

250-Watt/ 1- Kw
Harmonic Filter

549-2010-00

1.4 EQUIPMENT SUPPLIED.

Table 1- 2 lists equipment that is supplied as par t of
the 786M- 1 Stereo Generator.

1.7 EQUIPMENT SPECIFICATIONS.

1.7.1 MECHANICAL.
TABLE 1- 2
EQUIPMENT SUPPLIED

EQUIPMENT

786M- 1 Stereo Generator

COLLINS
PART NUMBER

522- 2914-00

Weight.

14 pounds approximately.

Size . .

19 inches wide , 10-1/ 2
inches high, 7 inches deep.

Ambient temperature
rang e

. ....

Ambient humidity
range

.

Altitude
1.5 EQUIPMENT REQUIRED BUT NOT SUPPLIED.

Table 1-3 lists equipment that is required for operation of the 786M-1 Stereo Generator but not supplied
as part of the 786M- 1.

4
STEAM POWERED RADIO.COM

+15°C (59°F) to 45°C
(113°F).
0 to 95% r e lat ive humidity.
0 to 7500 feet.

1.7.2 ELECTRICAL.
Power source . . •

20 ±0, 1 volts d-c.
28 ±2.8 volts d-c (for remote operation),

TD-537
786M- 1 Stereo Generator
Distortion . . . • . • Less than 0.5% over the
frequency range of 30 to
15,000 cps.

Balanced 600 ohms, left
and right channels.

Input

Input level • . • • . . 10 ±2 dbm for 100% composite modulatio n.
Frequency range

. . . 30 to 15,000 cps for each
channel.

Output level

280 ±50 mv peak to peak.

Pilot carrier
frequency

19 kc ±2 cps.

Pilot carrier level

Equivalen t to 9% ±1 % modulation of the main carrier.

Channel separation

Greater than 30 db, 50 cps
to 15,000 cps.

Crosstalk

38-kc subcarrie r
suppressio n

40 db below output with 10dbm input level.

Main channel and stereophonic subcarrie r
phase relationsh ip. • . ±3 degrees for audio frequencies from 50 to 15,000
cps.
Audio- frequency
response . . • .

More than 40 db below
single channel level.

Complies with FCC standard 75- microseco nd pre(right
curve
emphasis
channel only, left channel
pre- emphasis is obtained
from exciter).

1.8 SEMICONDUCTOR COMPLEMENT.
Table 1- 5 lists the s emicondu ctor compleme nt supplied as part of 786M-1 Stereo Generator .

TABLE 1-5. SEMICONDUCTOR COMPLEM ENT
FUNCTIO N

QUANTIT Y

TYPE

Q701

1

2Nl613

38- kc oscillator

Q702

1

2N1285

38- kc buffer

Q703

1

2N1613

38-kc driver

Q704

1

2N1285

38- kc isolation amplifier

Q705

1

2N708

19- kc locked oscillator

Q706

1

2Nl175A

Left audio amplifier

Q707

1

2Nl175A

Right audio amplifier

Q708

1

2N1285

Meter amplifier

CR702

4

1N270

Balanced modulator diode switches

SYMBOL

5
STEAM POWERED RADIO.COM

TD-537
786M-1 Stereo Generator

SECTION II
PRINCIPLES OF OPERATION
ear. The effect upon the listener of such a system is
to simulate placing the listener at a point midway
between the two microphones and receiving a true
representation of the originating sound source.

2.1 GENERAL.

The 786M-1 Stereo Generator provides facilities for
the conversion of stereophonic input signals to an output which conforms to the standards approved by the
FCC for the transmission of stereophonic signals.
The following paragraphs discuss stereophonic principles and the operation of the 78 6M-1 Stereo
Generator.
2.2 PRINCIPLES OF FM STEREO.

2,2.1 STEREOPHONIC SOUND SYSTEMS.
An elementary stereophonic sound system consists
of two directional microphones placed to the right and
left of a sound source. See figure 2-1. Each microphone in turn is connected to an amplifier and speaker
system. When the listener is situated between the
speakers, the left channel will be r eceived by the left
ear and the right channel will be received by the right

To provide a realistic stereo effect, the difference in
time delay and signal amplitude from the sound source
to each of the mic rophones must be mainta ined through
the entire stereo system. If the time delay or amplitude difference is changed in one of the amplifier or
speaker systems, the effect to the listener will be a
change in direction of the sound source, when in reality
no change has occurred. A change in time delay of the
left or right channel is referred to as a phase relationship change.
This phase relationship change
between the c hannels must be held, in stereo trans mitting equipment, to within ±3 degrees.
If the amplitude difference and time delay in each
system is identical (as when the sound source is centered be tween the microphones), the sound source will

SOUND SOURCE

RIGHT
CHANNEL
MICROPHONE

LEFT
CHANNEL
MICROPHONE

RIGHT
CHANNEL
A"'PLIFIER

LEFT
• CHANNEL
AMPLIFIEl't

RIGHT CHANNEL

LEFT CHANNEL

SPEAKER

SPEAKER

LISTENER

F igure 2-1. Elementary Stereophonic System

6
STEAM POWERED RADIO.COM

TD-537
786M-1 Stereo Generator

UJ
0

::,

1-...J

a.
:I!


oroz

0

2N 285119

· ::,

----------=-

PILOT
CARRIER PHASE
ADJUSTMENT
L7O4

CARRIER
BALANCE
CONTROL
R726

CARRIER
BALANCE
CONTROL
R 7O3

38 KC
FREQUENCY
ADJUSTMENT
L7O1

38KC
OSCILLATOR
GAIN
R713

.,.,

0

.G

0

!'.,'"" 1$

2N708

0

-

•.
•

0
0708

'ZNIZ8~

0

C)

Z Nlll~

0

~

0

G)

•

(I

STD£0-MON
lfflilOTt O O N ~
311 KC OSC
lfON It
~KCIIUf
l'lJUt

..

L I.K

nM••
'HICCDR'IVEA

• •

.\
QIAN S£

L•R AMPL

e:.

M7O1
MULTIMETER

S7O3
METER
SELECTOR

S7O1
INPUT
CONTROL

S7O2
PILOT
CARRIER
ON

R748
PILOT
CARRIER
LE VEL

R755
CHANNEL
SEPARATION
AMPLI T UDE
ADJUSTMENT

F i gure 2- 8. 786M-1 Control and Adjustmen t Locat ions
and f eeding it into the base of Q701. The 38-kc output
of L 701 is also capacitive ly coupled into the 38-kc
buffer amplifi er, Q702. The output of Q702 is tuned to
38 kc byC714an dL702. The outputofb uffer amplifier
Q702 is further amplified to approxima tely 4 volts peak
to peak by driver amplifier Q703. The gains of Q701,
Q702, and Q703 are stabilized by emitter degenerat ion
to reduce gain variations between transistor s. The
output of Q703 is capacitive ly coupl ed to the primary
of T701 (balanced modulator switching transform er)
and to the 19-kc pilot carrier locked oscillator through
an isolation stage , Q704.
The pilot carrier oscillator , Q705, is basically a
grounded base oscillator which is synchroni zed by
injecting a 38- kc signal into the base. The oscillator
output is a 19-kc r esonant tank placed across the base
to emitter junction by m eans of a capacity voltage
divid e r. T he 19- kc output is taken from the emitte r
circuit and is injected into the output of FL705. The
p ilot carrier phase, which must b e maintaine d in phase
with the output of FL705, is adjusted by varying the
inductance of L704. Pilot carri er l evel is adjusted with
R748.
Metering circuits are provided within the 786M-l t o
Meter amplifier Q705
assi st in trouble shooting.

provides isolation of the matrixing and oscillator
circuits from the m etering circuits. The right audio
and l eft audio channel s are fed directly from the 600ohm balanced input through met er multip lying r esistors R711 and R710 to meter M701.
2.3.2 CONTROL FUNCTION S.
The following paragraph s desc ribe the functions of all
controls in the 786M- 1 Stereo Generator . Refer to
figure 2-8 for contr ol locations.
Meter selecto r S703 connects met er M7 01 into various
c ircuits for monitorin g pur poses. The mete ring positions are as follows; L AUDIO (left audio), R AUDIO
(right audio), MXOUTP UT (multiplex output), RAUDIO
OSC (38-kc oscillator ), 38 KC BUF (38-kc buffer
amplifier) , 38 KC DRIVER. and 19 KC LKD OSC (19kc locked oscillator output).
Audio input switch S701 sel ects one of three possible
audio inputs; left audio, right audio, and ste r eo, If
switch S701 i s placed in the left audio or right audio
positions, remote r elay K701 i s able to provide r emote
control over the monaural or ster eo m odes. When
S701 is in the stereo mode, r elay K701 is disabl ed and
has no effect on ster eo gene r ator inputs.
11

STEAM POWERED RADIO.COM

TD-537
786M- 1 Stereo Genera tor
CARRIE R BALANCE controls R703 and R726 balance
out the 38-kc carrier and 76-kc second harmon ic in
the seconda ry of T701. These controls are adjusted
for zero indicati on at TP701 with no audio in either
channel .
Channe l separati on L+R amplitu de control (CHAN SEP
L+R AMPL} R755 adjusts the amount of L+R fed
around the balance d modula tor to raise the L+R level
by _!.
7T
Inducto r L 701 adjusts the frequen cy of the 38-kc oscillator . Resisto r R713 adjusts the level of the 38- kc

driver output into the balance d modula tor. This level
is set for 6 volts peak to peak at TP701 at the factory
and should never need readjus tment.
PILOT CARRIE R PHASE control L704 adjusts the
phase of the 19-kc pilot carrier . The control is set for
an in-phas e conditio n with relation to the output of
FL705. PILOT CARRIE R LEVEL control R748 adjusts
the level of the 19-kcpi lotcarrier . This control is set
for 0. 009 volt rms at TP701. PILOT CARRIE R switch
S702 turns the 19-kcp ilotcarr ieroffan don fo r adjustment and testing purpose s.

SECTION Ill
MAINTENANCE
3. 1 GENERAL.

This section contain s informa tion concern ing the
mainten ance of the 786M-1 Stereo Genera tor.
NOTE
As some transist or cases are el ectrical ly
above ground, do not short transist or cases
to ground or damage to the transist or may
result. Always replace transist ors with the
transist or locating mark placed adjacen t to
the transist o r socket.
3.2 SERVIC ING TRANSI ST()R CIRCUITS.

Servicin g procedu res and test equipm ents that have
been. us ed in the past with other types of electron ic
equipme nt, for the most part, may be used with
transist or circuits . Some special precaut ions which
must be used are listed below.
3.2.1 TEST EQUIPM ENT.
Damage to transist ors by test equipm ent is usually
the result of acciden tally applyin g too much voltage
to the transist or element s. Commo n causes of damage
from test equipme nt are as follows;
a. Test equipme nt with a transfo rmerles s power
supply is one source of such voltage. This type of
test equipm ent can be used by employi ng an isolation transfo rmer in the power line.
b. It is still possible to damage transist ors from
line voltage even though the test equipm ent has a
power transfo rmer in the power supply, if the test
equipme nt is equippe d with a line filter. This filter
may act like a voltage divider and apply 55 volts
a-c to the transist or. To elimina te trouble from this
situatio n, connect a ground wire from the chassis of
the test equipm ent to the chassis of the equipme nt
under test before making any other connect ions.
c. Another cause of transist or damage is a multimeter that require s excessi ve current for adequat e
12
STEAM POWERED RADIO.COM

indicati ons. Multim eters that have sensitiv ities of
l ess than 5000 ohms per volt should not be used. A
multim eter with lower sensitiv ity will draw too much
current through many types of transistors and damage
them. Use of 20,000- ohm- per-vol t meters or vacuum tube volt meters is recomm ended. Check the ohmme ter
circuits (even those in vtvm's) on all scales with an
externa l, low-res istance milliam meter in series with
the ohmme ter leads. If the ohmme ter draws·m ore than
one milliam pere on any range, this range cannot be
used safely on small transist ors.
3.2.2 ELECTR IC SOIDER ING IRONS.
The followin g are possibl e causes of transist or
damage from solderin g irons;
a . Electric solderin g irons may damage transis tors through leakage current . To check a solderin g
iron for l eakage current , connect an a - c volt meter
between the lip of the iron and a ground connection,
allow the iron to heat, then check for a-c voltage
with the meter. Reverse the plug in the a - c receptacle and again check for voltage. If there is any
indicati on on the meter, isolate the iron from the
a-c line with a transfo rmer. The iron may be used
without the isolatio n transfo rmer if the iron is
plugged in and brought to tempera ture then unplugg ed
for the solderin g operatio n. It is also possibl e to
use a ground wire between the tip of the iron and the
chassis of the equipme nt being repaire d to prevent
damage from leakage current .
b. Light-d uty solderin g irons of 20 to 25 watts
capacity are adequat e for transist or work and s hould
be used. If it is necessa ry to use a heavier duty
iron, wrap a piece of number 10 copper wire around
the tip of the iron and make it extend beyond the tip
of the iron. Tin the end of the piece of copper wire
and use it as the solderin g tip.
3.2.3 SERVIC ING PRACT ICES.

a . If a transist or is to be evaluate d in an externa l
t est circuit, be sure that no more voltage is applied

TD-537
786M-l Stereo Generator
to the transistor than normally is used in the circuit
from which it came.
b. Test prods should be clean and sharp. Because
many of the resistors used in transistor ized equipments have low values . any additional resistance
produced by a dirty test prod will make a good resistor appear to be out of tolerance.
3.2.4 TROUBLE SHOOTING .
The usual trouble-sh ooting practices apply to transistors. Be sure the test equipment and tools meet
the requireme nts outlined in the above paragraph s.
It is recommen ded that transistor testers be used to
evaluate the transistor .

If a transistor tester is not available, a good ohmmeter may be used for testing. Be sure the ohmmeter meets the requireme nts as set forth in the
paragraph on test equipment , above. To check a -PNP
transistor , connect the positive lead of the ohmmeter
to base and the negative lead to the emitter. (The
red l ead is not necessaril y the positive lead on all
Generally , a resistance reading of
ohmmeter s.)
50,000 ohms or m ore should be obtained. Connect
the negative lead to the collector; again a reading of
50,000 ohms or more should be obtai ned. Reconnect
the circuit with the negative lead of the ohmm eter to
With the positive l ead connected to the
the base.
emitter, a value of resistance in the order of 500
ohms or less should be obtained. Likewise, with the
positive lead connected to the collector, a value of
500 ohms or l ess should be obtained.
Similar tests made on an NPN transistor produce
results as follows: With the negative ohmmeter lead
connected to the base, the value of resistance between
the base and the emitter a nd between the base and
the collector should be high. With the positive lead
of the ohmmeter connected to the base, the value of
resistance between the base and the emitter and
between the base and collector should be low. If the
readings do not check out as indicated, the transistor
probably is defective and should be replaced.

If a defective trans istor is found, make sure
that the circuit is in good operating order
before inserting the replaceme nt transistor .

Make sure that the value of the bias resistors in
series with the various transistor elements are as
shown on the schematic diagram. The transistor is
very sensitive to improper bias voltages; therefore,
a short or open circuit in the bias resistors may
For this reason, do not
damage the transistor .
trouble-sh oot by shorting various points in the circuit to ground and listening for clicks.
3.3 TROUBLE SHOOTIN G.

Trouble shooting can best be accomplis hed by using
Suspected
standard trouble-sh ooting techniques .
troubles should be isolated to individual stages before

componen ts are repl aced. The pilot carrier can be
turned off with switch S702 as an aid in trouble
shooting and testing.
3.4 ADJUSTM ENTS AND TESTS.

The 786M-1 is fitted with adjustmen ts which adjust
38-kc oscillator tuning, carrier balance, pilot carrier
l evel , and pilot car rier phase.

NOTE
Do not attempt the following adjustmen ts
without using the proper test equipment as
serious deteriorat ion of the 786M-1 output
quality may result from the use of inferior
test equipment .
The test equipment s or their equivalent s required to
perform the specified tests are listed in table 3-1.

TABLE 3-1
TEST EQUIPME NT REQUIRE D

EQUIPME NT

MANUFAC TURER
AND TYPE

Oscillosco pe

Tektronix Model 545A with
Type 53/ 54C plug-in unit and
a Type D plug-in unit

Oscillator

Hewlett-P ackard Model 200AB

Distortion and
noise meter

Hewlett-P ackard Model 330D

Vtvm

Hewlett-P ackard Model 400H
(or equivalent )

Figure 3-1 is a standard transistor base, viewed from
the bottom, which provides a transistor element
reference .
3.4.1 38-KC OSCILLAT OR TUNING.
Turn on the A830- 2 10 W Wide-Ban d FM Exciter.
Connect an a-c vtvm to the collector of Q702. (See
figure 3- 1.) Turn R713 fully clockwise . Adjust L 701
for a maximum indication on the vtvm. The oscillator
output at the collector of Q702 should be approxima tely
1.5 volts.
13

STEAM POWERED RADIO.COM

TD-537
786M-l Stereo Generator
COLLECTOR

EMITTER

plug-in unit to TP702 and ground. Adjust in turn
R703 and R726 in small steps for a minimum indication on the oscilloscope. The final indication on the
oscilloscope must be more than 40 db below 100
millivolts (10 millivolts).

BASE

3.4.4 PILOT CARRIER PHASE.
COLLECTOR

EMITTER

BASE

Figure 3- 1. Transistor Base Configuration

3.4 .2 38-KC AMPLITUDE CHECK.
Connect a calibrated Tektronix oscilloscope, provided
with a Type D plug- in unit, across terminals 1 and 2
of T701. The voltage at this point should be 6 volts
peak to peak as react on the oscilloscope. Adjust
R713 if necessary to obtain 6 volts.
3.4.3 CARRIER BALANCE.
Turn the PILOT CARRIER switch to OFF. Remove
any a•.1dio from the left and right audio channels.
Connect the Tektronix oscilloscope with the Type D

Connect the Tektronix oscilloscope to the 786M-1
Stereo Generator as shown in figure 3- 2. Connect
the audio oscillator into the 786M-1 through 10- db
pads to give an L= -R signal (right audio channel 180
degrees out of phase with the left audio channel) into
the audio input terminals at a frequency of 1000 cps
and a level of 7 .8 volts nus. Set the PILOT CARRIER
switch to OFF.
Switch the CONTROL switch to
STEREO ON. Adjust the P.ILOT CARRIER PHASE
control until both traces on the oscilloscope are
stationary and an exact coincidence of the zero crossings of the 19- kc pilot carrier and the L - R signal
is obtained as shown in figure 3-3. Expand the sweep
to 5X, and adjust the horizontal position knob to check
the two points of coincident zero crossing.
3.4.5 PILOT CARRIER LEVEL.
Remove any audio from the 786M-1 audio input channels
and connect a vtvm to TP702. Set the PILOT CARRIER
switch to ON, and adjust the PILOT CARRIER LEVEL
control for a reading of 0.009 volt rms as react on
the vtvm.

TR IGGER INPUT

TYPE 53/54C
PLUG-IN UNIT

702

Gili:1iR{p
P 70 I

---------K.J

CONTROL SETTINGS
I. CHANNEL A

0.05 V/CM, TP702

2.CHANNEL

0.05 V/CM,

B

3. MODE -ALTERNATE
4. TR IGGERING MODE - AUTOMATIC TRIGGER SLOPE + EXTERNAL
5. SWEEP T IME/CM 5 USEC
6. MAGNIF IER

XI, X5

Figure 3-2. Pilot Carrier Phas e Te st Setup
14
STEAM POWERED RADIO.COM

TP701

TD-537
786M- l Stereo Generator

I~

MALADJUSTMENT OF PILOT
CARRIER PHASE CONTROL.

PROPER ADJUSTMENT OF PILOT
CARRIER PHASE CONTROL.

PROPER ADJUSTMENT OF PILO1
CARRIER PHASE CONTROL, EX
PANDED HORIZONTAL DEFLEC TION.

Figure 3- 3. Pilot Carrier Phase Adjustment, Oscilloscope Pattern

15
STEAM POWERED RADIO.COM

TD- 537
786M-1 Stereo Generato r
3.4.6 CHANNE L SEPARA TION ADJUST MENT.
Set the audio oscillato r to 5000 cps, and connect it
to the left audio input of the 786M-1. Connect-the
Tektroni x oscillosc ope with the type D plug-in unit
to TP702 and ground, and adjust the audio oscillato r
for a 300- millivolt peak- to-peak indicatio n on the
oscillosc ope. Adjust the CHAN SEP L+R AMPL control to produce a straight zero axis (within 4 millivolt s)
as shown in figure 3- 4. Repeat with the audio input into
the right audio channel. The final adjustme nt must
bring the zero axis to within 4 millivolt s of a straight
zero axis.

3.5 MINIMUM PERFORMANCE STANDARDS.
3.5.1 OVER - ALL GAIN.
a. Connect the Tektroni x oscillosc ope to TP702 and
ground.
b. Switch the PILOT CARRIE R switch to OFF.
c. Connect the audio oscillato r through 10-db pads to
the 786M- l in such a way to obtain an L=R s ignal (left
channel equal fn amplitud e and phase with right
channel) .
d. Adjust the audio oscillato r frequenc y to 1000 cps,
and adjust the audio oscillato r output to obtain O VU on
the 786M- 1 VU m eter when the METER switch is set
to L AUDIO or R AUDIO. The peak-to- peak indicatio n
on the oscillosc ope shall be from 200 to 300 millivolt s.
e. Connect the audio input so L= -R (right channel
equal in amplitud e but 180 degrees out of phase with

MALADJUS TMENT OF CHANNEL
SEPARATIO N L ,'IND R AMPL
CONTROL.

the left channel) . The peak- to-peak indicatio n shall be
from 200 to 300 millivolt s.
3. 5.2 FREQUE NCY RESPONSE.
a. Connect the distortio n analyzer between TP702
and ground.
b. Switch the PILOT CARRIE R switch to OFF.
c. Connect the audio oscillato r through 10-db pads to
each channel in such a way to obtain an L =R signal
(le ft channel equal in amplitude and in phase with right
channel) .
d. Adjust the audio oscillato r frequenc y to 1000 cps,
and adjust the audio oscillato r output to obtain O VU on
the 786M-1 VU meter when the METER switch is set
to L AUDIO. Set the distortio n analyzer to O db.
e. Set the audio oscillato r to 50 cps, and adjust the
audio level from the audio oscillato r for O VU on the
786M-1 VU meter. The indicatio n on the distortio n
analyze r shall be within ±0.5 db of the level at 1000
cps.
f. Repeat step e at 15,000 cps. The indicatio n on the
distortio n analyzer shall be within ±1.5 db of the level
at 1000 cps.
g. Repeat steps d, e, and f with the METER s witch
set at R AUDIO.
3.5.3 HARMONIC DISTORT ION.
a. Connect the test setup as describe d inparagr aph
3.5.2, s teps a, b, and c .
b. The distortio n at 50, 1000, and 15,000 cps should
be not more than one percent.

PROPER ADJUSTME NT OF CHANNEL
SEPARATION LAND R AMPL CONTROL.

Figure 3-4. Channel Separati on Adjustm ent, Oscillosc ope Pattern

16
STEAM POWERED RADIO.COM

TD- 537
786M- l Stereo Generator

SECTION IV
PARTS LIST
ITEM

DESCRIPTION

786M-l STEREO GENERATOR

COLLINS
PART NUMBER

ITEM

DESCRIPTION

522- 2914-00

•C737

CAPACITOR, FIXED, CERAMIC:
500 v d-c; MIL type CC20CH050D
CAPACITOR, FIXED, CERAMIC:
500 v d-c; MIL type CC20CH100D
CAPACITOR, FIXED, CERAMIC:
500 v d-c; MIL type CC20CK010D
CAPACITOR. FIXED. CERAMIC:
500 v d - c; MIL type CC20CK020D
CAPACITOR, FIXED, CERAMIC:
500 v d-c; MIL type CC20CJ030D
CAPACITOR, FIXED, CERAMIC:
500 v d- c; MIL t ype CC20CH040D
CAPACITOR, FIXED, CERAMIC:
500 v d-c: MIL type CC20CK010D
CAPACITOR, FIXED, CERAMIC:
500 v d- c; MIL type CC20CK020D
CAPACITOR, FIXED, CERAMIC:
500 v d- c; MIL t ype CC20CJ030D
CAPACITOR, FIXED, CERAMIC:
500 v d-c; MIL type CC20CH040D
NOT USED
SEMICONDUCTOR DEVICE, SET:

•C737
C701
C702
C703
C704
C705

C706
C707
C708
C709

CAPACITOR, FIXED, ELECTROLYTIC: 30 uf
-10%+100%, 10 V d-c
CAPACITOR, FIXED, E LECTROLYTIC: 50 ul
-10% +100%, 25 V d-c
CAPACITOR, FIXED, ELECTROLYTIC: same as
C701
CAPACITOR, FIXED, ELECTROLYT IC: same as
C702
CAPACITOR, FIXED, E LECTROLYTIC: 250 ul
-10% +100%, 12 v d - c; Sprague Electr i c part no.
30D157Al
CAPACITOR, FIXED, ELECTROLYTIC: same as
C705
CAPACITOR, FIXED, ELECTROLYTIC: 15 ul
-H>% + 100%, 25 v d-c; Sprague E lectri c part no.
40D180Al
CAPACITOR, FIXED, MICA: 6800 Uuf : 10%, 300 V
d- c
CAPACITOR, F IXED, PAPER: 0 .047 ul :10%, 400
v

C710
C711

C712
C713
C714
C715
C716
thru
C719
C720
C72 1
C722
C723
C724
C725
C726

C727
C728
C729
C730
C731
C732
C733
thru
C735
*C736
*C736
*C736
*C736

d-Cj

183-1377- 00
•C738
183-1379- 00
•C738
183-1377- 00
*C738
183-1379- 00
*C738
183-1190-00
*C739
183- 1190-00

*C739

183-1362-00

*C739
•C739

935-2110-00
931-0295-00

Sprague Electric part no. 160P47394

CAPACITOR, FIXED, PAPER : 0.1 uf : 10%, 400 V
d- c; Sprague Electric part no. 160Pl0494
CAPACITOR, FIXED, ELECTROLYTIC: 20 ul
- 10% +100%, 25 v d - c; Spr ague Electric part no.
40Dl81A2
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, MICA: 1800 uul :5%, 500 v
d-c; Electro Motive part no. DM20Fl82J500WV
CAPACITOR, FIXED, PAPER: same as C710
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, MICA: 510 Uuf ±5%, 500 V
d - Cj Electro Motive part no. DM19E511J
CAPACITOR, FIXED, ELECTROLYTIC : same as
C711
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, PAPER: same as C710
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, MICA: 10,000 uul ±2%, 500
v d-c; Electro Motive part no. DM30F103G
CAPACITOR, FIXED, FILM: 0.1 uf, ±1%, 50V
d-c; Sprague El ectric Co. part no. 114Pl041
R5S4
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, ELECTROLYTIC: 20 ul
-10% + 100%, 50 v d-c
CAPACITOR, FIXED, ELECTROLYTIC: same as
C711
CAPACITOR, FIXED, CERAMIC: 4 700 uuf ±20%,
500 v d-c; MIL type CK62AW472M
CAPACITOR, FIXED, CERAMIC : sam e as C732
CAPACITOR, FIXED, C ERAMIC:
500 v d -c; MIL type CC20CH0 50D
CAPAC ITOR, FIXED, CERAMIC:
500 v d-c; MIL type CC20CH100D
CAPACITOR, FIXED, CERAMIC:
v d-c; MIL type CC20CHI 50J
CAPACITOR, FIXED, CERAMIC:
500 v d-c; MIL type CC20CH200J

931- 0299- 00

CR701
CR702
A,B,C,
&D

FL701
183- 1365-00
FL702
183-1365-00
183-1365-00
F L703
912-3333-00
931-0299-00
183-1365-00

FL704
FL705

9 12 - 2980- 00

COLLINS
PART NUMBER
5 uul ±1/ 2 uuf,

916- 0118-00

10 uul :V2 uul,

916- 0138- 00

1.0 uul ±1/ 2 uul,

916-0071-00

2.0 uuf ¼1/2 uuf.

916-0076-00

3.0 uuf :1/2 uuf,

916-0145-00

4.0 uul ±1/ 2 uuf,

9 16- 0 114-00

1.0 uul ±1/ 2 uuf,

916-0071-00

2.0 uuf ±1/ 2 uul,

916- 0076- 00

3. 0 uuf ±1/ 2 u uf,

916-0145-00

4 . 0 uul ±1/ 2 uul,

916- 0 114- 00

lour hermeti-

353-2041 - 00

cally sealed matched germanium diodes; Hughes
Products part no. MQ4032

ATTENUATOR, FIXED: p r e - emphasis network
for u/in FM commercial broadcast equipment: 75
microseconds, 600 ohms input and output
FILTER, HIGH PASS: metal e ncased, hermetically
seal ed, input 600 ohms, output 600 ohms, 4 soldertype terminals, continuous du ty cycle; A.D.C.
part no. D10390
FILTER, LOW PASS: continuous duty cycle , input
600 ohms ±20%, output 600 ohms :20%, metal
encased, hermetically sealed; C.A.C . part no.
90-1015-00
FILTER, LOW PASS: same as FL703
FILTER, LOW PASS: linear, continuous duty
cycle, input 600 ohms :20%, output 600 ohms :20%,
metal encased, hermetically sealed, solder- type

379-0426- 00

673-0869- 00

673-0871-00

673-0871-00
673- 0870- 00

terminal s ; C.A.C . part no . 90-1012-00

183-1365-00

J701

183- 1365- 00

J702

931-0299-00
183- 1365- 00

K701

912- 2734- 00
L701
933-0279-00
183-1365-00

L702

183-1365-00
183-1365-00

L 703
L704

183-1369-00
M701
183-1365-00
913-1187-00

0701

913-1187-00

0702
P701

5 uuf ±1/2 uuf,

916-0118-00

10 uuf :1/ 2 uul,

916-0138- 00

15 uul ±5%, 500

916- 0671-00

20.0 uuf :5%,

916-0677- 00

Q701
Q702
Q703
Q704
Q705

JACK, TIP: insulated !or u/ w 0 .080 in. test
probes; brown; E .F. J ohnson part no. 105-208-200
JACK, TIP; insulated !or u/ w 0.080 in. test
probes; red; E .F. J ohnson part no. 105- 202- 200
RELAY, ARMATURE: 4 C contact arrangem ent;
0.25 amp, 300 v d- c, 1 inductive winding, 250 ohms

r esistance, 27.5 v d-c; 0 .11 amp approx operating
current; Aemco, Inc. part no. 94- 3473
COIL, RADIO FREQUENCY: multilayer solenoid
type windingi 2.3 ohms; - 15°C to +55°C; 0.5 to
3 .5 mh; Chicago Standard T ransformer Corp . part
no. WC-7
COIL, RADIO FREQUENCY: s ingle layer wound,
10,000 uh, 66 .5 ohm s d-c, 75 ma current rating;
Delevan part no. 2500-76
COIL, RADIO FREQUENCY: same as L 702
8OIL, RADIO FREQUENCY: 8 mh inductance;
w/ core; 1- 5/ 32 i n. by 1- 5/ 32 in. by 2- 1/ 2 in . excl
terminals; Communications Coil part no. X-544-2
METER, AUDIO LEVEL: VU Meler !or use in
equipments exposed to environments; background
color, white
KNOB: setscrew type; black phenolic body; 1.125
in . dia by 0.843 in. thk w/ skirt
KNOB: same as 0701
PLUG. TELEPHONE : brass; phenolic insulation,
w/ solder-lug terminal; Switchcraft part no.
3501MC
TRANSISTOR: hermetically sealed NPN diffused
silicon planar transistor; Fairchild Sem iconductor
Cor p. part no. 2Nl613
TRANSISTOR: germanium; RCA part no. 2Nl 285
TRANSISTOR: same as Q701
TRANSISTOR: same as Q702
TRANSISTOR: hermetically sealed; NPN siliconj
Fairch ild Semiconductor Corp. part no. 2N708

360-0152- 00
360- 0 150-00
974- 0 127- 00

278-0734-00

240-2564-00

240- 2564- 00
278- 0780- 00

456-0056-00
546- 1294- 003
546-1294-003
361 - 0062-00
352- 0349- 00
352- 0243-00
352-0349- 00
352- 0243- 00
352-0322-00

*Sel ected and added by test in the vicinity of TB714, TB718, and T701

17

STEAM POWERED RADIO.COM

TD-537
786M-l Stereo Generator

ITEM

DESCRIPTION

COLLINS
PART NUMBER

352- 0315-00
TRANSISTOR: hermetically sealed, PNP germanium; General Electric part no. 2Nll 75A
352- 0315-00
Q707
TRANSISTOR: same as Q706
352-0243- 00
Q708
TRANSISTOR: same as Q702
705- 7090-00
w
4
1/
±1%,
ohms
750
RESISTOR, FIXED, FILM:
R701
00
705-7090R701
as
same
FILM:
FIXED,
RESISTOR,
R702
377- 0113-00
R703
RESISTOR, VARIABLE, WIREWOUND: 10 ohms
±10%, 2 w
745- 1377-00
RESISTOR, FIXED, COMPOSITION : 3900 ohms
R704
±10%, 1/ 2 w
745-1401-00
R705
RESISTOR, FIXED, COMPOSITION : 15,000 ohms
±10%, 1/ 2 w
745-1373-00
R706
RESISTOR. FIXED. COMPOSITION : 3300 ohms
%10%, 1/ 2 w
1377-00
745R704
as
R707
RESISTOR, FIXED, COMPOSITION : same
R708
RESISTOR, FIXED, COMPOSITION : same as R705 745-1401-00
RESISTOR, FIXED, COMPOSITION: same as R706 745-1373-00
R709
705-7102-00
RESISTOR, FIXED, FILM: 1330 ohms ±1 %, 1/ 4 w
R710
705-7102-00
RESISTOR, FIXED, FILM: same as R710
R711
745- 1415-00
ohms
R712
RESISTOR, FIXED, COMPOSITION: 33,000
±10%, 1/ 2 w
376-0205-00
R713
RESISTOR. VARL.\BLE, COMPOSITION: 5000
ohms ±20%, 0.2 w
745-1394-00
R714
RESISTOR, FIXED. COMPOSITION: 10,000 ohms
±IO%, 1/2 w
745-1314- 00
RESISTOR, FIXED, COMPOSITION : 120 ohms
R715
±10%, J / 2 w
745-1380-00
RESISTOR, FIXED, COMPOSITION : 4700 ohms
R716
±10%, 1/ 2 w
745-1 352-00
ohms
RESISTOR, FIXED, COMPOSITION : 1000
R717
±10%, 1/ 2 w
RESISTOR, FIXED, COMPOSITION : same as R712 745-1415-00
R718
745- I 398-00
RESISTOR, FIXED, COMPOSITION: 12.000 ohms
R719
±10%, 1/2 w
745-1 387-00
ohms
RESISTOR, FIXED, COMPOSITION: 6800
R720
±10%, 1/ 2 w
745-1321-00
RESlSTOR, FIXED. COMPOSITION: 180 ohms
R721
±10%, 1/ 2 w
745- 1370-00
RESISTOR. FIXED, COMPOSITION : 2700 ohms
R722
±10%. 1/2 w
745- 1293-00
RESISTOR, FIXED, COMPOSITION: 39 ohms
R723
±10%, 1/ 2 w
705-7110-00
RESlSTOR, FIXED, FILM: 1960 ohms±!%, 1/4 w
R724
705-7080-00
RESlSTOR, FIXED, FILM: 464 ohms±!%, 1/4 w
R725
377-0113-00
as
same
WIREWOUND:
RESISTOR. VARL.... BLE,
R726
R703
705-7080-00
RESISTOR. FIXED, FILM: same as R725
R727
705- 7080-00
RESISTOR, FIXED, FILM: same as R725
R728
705-7080- 00
RESlSTOR, FIXED, FILM: same as R725
R729
705-7110-00
RESISTOR, FIXED, FILM: same as R724
R730
RESISTOR, FIXED, COMPOSITION: same as R716 745- 1380-00
R73I
RESlSTOR, FIXED, COMPOSITION: same as R706 745-1373-00
R732
745-1317- 00
RESISTOR, FIXED, COMPOSITION: 150 ohms
R733
±10%, J/ 2 w
745-1401-00
R705
as
same
:
RESISTOR, FIXED, COMPOSITION
R734
705- 7150-00
RESlSTOR, FIXED, FILM: 13,300 ohms ±1%,
R735
1/ 4 w
745-1342-00
RESlSTOR, FIXED, COMPOSITION: 560 ohms
R736
±10%, 1/ 2 w
745-1422-00
R719
as
same
:
RESISTOR, FrxED, COMPOSITION
R737
RESISTOR, FIXED, COMPOSITION: same as R733 745-1317-00
R738
745- 1422-00
RESISTOR, FIXED, COMPOSITION: same as R719
R739
745-1394-00
RESISTOR, FIXED, COMPOSITION: same as R714
R740
705-7070-00
RESISTOR, FIXED, FILM: 287 ohms ±1%, 1/4 w
R741
745-1391-00
R720
as
RESISTOR, FIXED, COMPOSITION : same
R742
RESISTOR, FIXED, COMPOSITION: same as R716 745- 1380-00
R743
745-1352-00
RESISTOR, FIXED, COMPOSITION : same as R?l 7
R744
RESISTOR, FIXED, COMPOSITION: same as R''16 745- 1380-00
R745
745-1380-00
RESISTOR, FIXED, COMPOSITION : same as R716
R746
745- 1380-00
RESISTOR, FIXED, COMPOSITION : same as R716
R747
376- 4730-00
RESISTOR, VARIABLE: composition: 10,000 ohms
R748
±30%, 1/ 4 w
745-1415-00
RESISTOR, FIXED, COMPOSITION: same as R712
R749
705-7084-00
RESlSTOR, FIXED, FILM: 562 ohms ±1%, 1/ 4 w
R750
705-7068-00
w
4
1/
RESlSTOR, FIXED, FILM: 261 ohms±!%,
R75I
705-7068-00
RESlSTOR, FIXED, FILM: same as R751
R752
745-1394-00
RESlSTOR, FIXED, COMPOSITION: same as R714
R753
745-1394-00
RESlSTOR, FIXED, COMPOSITION: same as R714
R754
376-4725-00
RESlSTOR. VARIABLE: composition; 250 ohms
R755
±20%, J/ 4 w
705- 7086-00
RESISTOR, FIXED, FILM: 619 ohms ±I%, 1/ 4 w
R756
745- 1342-00
RESlSTOR, FIXED, COMPOSITION : same as R736
R757
745-1342-00
RESlSTOR, FrxED, COMPOSITION: same as R736
R758
745-1293-00
R723
as
same
RESISTOR , FIXED, COMPOSITION:
R759

Q706

18

STEAM POWERED RADIO.COM

ITEM

DESCRIPTION

RESISTOR, FIXED, COMPOSITION : same as R719
RESISTOR, FIXED, FILM: same as R724
RESISTOR, FIXED, COMPOSITION : same as R717
RESISTOR, FIXED, COMPOSITION : 390 ohms
±10%, 1/2 w
R764
RESISTOR, FIXED, COMPOSITION : 0.12 megohm
±10%, 1/ 2 w
R765
RESISTOR, FIXED, FILM: 5110 ohms ±1%, 1/ 4 w
R766
RESISTOR, FIXED, FILM: same a s R765
R767
RESISTOR, FIXED, FILM: same as R765
R768
RESISTOR, FIXED, FILM: same as R765
RESISTOR, FIXED, COMPOSITION: same as R717
R769
R770
RESISTOR, FIXED, COMPOSITION: same as R719
RESISTOR, FIXED, COMPOSITION : same as R705
R771
R772
RESISTOR. FIXED. COMPOSJT!OK: same as R705
SWITCH SECTION, ROTARY: 6 circuit, 3 position;
S701
3 section; 4 moving, 16 fixed contacts; Oak Mfg.
Co. part no. 222274-AH3
SWITCH, TOGGLE: spdt; 40 amp continuous; 28 v
S702
d- c, 20 amp resistive, 15 amp inductance; 115 v.
400 cps, 10 amp resistance, 10 amp inductance;
Hetherington, Inc. part no. T 1003-AN
SWITCH SECTION. ROTARY: 4 circuit. 7 position,
S703
4 section; 3 moving, 24 fixed contacts; Grigsby
Allison Co.. Inc . part no. A25242- 4MLR-4
TRANSFORME R, RADIO FREQUENCY, BALT701
ANCED: c/ o plastic fabric base phenolic board
1/ 16 in. by 1-3/ 16 in. by 1-3/ 16 in.; plus 3 coils,
75 turns ea; coil # 1, wound ccw, coils #2 and #3,
cw; plus plastic rod 0.159 in. w by 0 .413 in. dia
TB701 TERMINAL BOARD: phenolic, barrier type w/ lug
for back connection; 12 terminals
TB702 TERMINAL BOARD: bakelite, 4 terminals, 3/ 8 in.
by 1/ 2 in. by 1-1/ 2 in.; Cinch Mfg. Corp. part no.
1534-A
TB703 TERMINAL BOARD: same as TB702
TB704 TERMINAL BOARD: 4 solder-lug terminals,
brass; 3/ 8 in. by 1-1/ 2 in. overall
TB705 TERMINAL BOARD: phenolic. 4 brass solder lug
terminals; 1/ 16 in. by 3/ 8 in. by 1-1/2 in.; Cinch
M!g. Corp. part no. 1532A
TB706 TERMINAL BOARD: phenolic, 3 solder-lug
terminals; 11/ 16 in. by 1-1/ 8 in. lg
TB707 TERMINAL BOARD: same as TB706
TB708 TERMINAL BOARD: same as TB702
TB709 TERMINAL BOARD: phenolic, 5 brass solder lug
terminal s; 1/16 in. by 3/ 8 in. by 1-7/ 8 in.; Cinch
Mfg. Corp. part no. 1542-A-FV
TB710 TERMINAL BOARD: same as TB702
TB711 TERMINAL BOARD: laminated phenolic w/ 4
solder lug terminals; 27/ 32 in. w by 1- 1/ 2 in. lg;
Cinch Mfg. Corp. part no. 1909
TB712 TERMINAL BOARD: same as TB702
TB7l3 TERMINAL BOARD: same as TB706
TB714 TERMINAL BOARD: same as TB711
TB715 TERMINAL BOARD: same as TB711
TB716 TERMINAL BOARD: phenolic w/ 3 solder- lug
terminals; 11/ 16 in. w by 1-1/ 8 in. lg; Cinch Mfg.
Corp. part no. 1520-A
TB717 TERMINAL BOARD: phenolic w/ 3 solder-lug
terminals; 11/ 16 in. w by 1-1/8 in. lg; Cinch Mfg.
Corp. part no. 1525A
TB718 TERMINAL BOARD: same as TB704
TB719 TERMINAL BOARD: same as TB702
TB720 TERMINAL BOARD: same as TB717
TB721 TERMINAL BOARD: same as TB704
XFL701 SOCKET, ELECTRON TUBE: 8 pr ong octal tube
socket w/ steel mtg plate; Amphenol- Borg
Electronics part no. 88-8TM
XQ701 SOCKET, TRANSlSTOR: 3 contacts spaced on
0.200 in. dia circle; Elco corp. part no. 3307X
XQ702 SOCKET. TRANSISTOR: 4 contacts spaced on
0:200 in. dia circl e; Elco Corp. part no. 3307
XQ703 SOCKET. TRANSISTOR: same as XQ701
XQ704 SOCKET. TRANSISTOR: same as XQ702
XQ705 SOCKET, TRANSISTOR: same as XQ701
XQ706 SOCKET, TRANSISTOR: same as XQ702
XQ707 SOCKET, TRANSISTOR: same as XQ702
XQ708 SOCKET, TRANSlSTOR: same as XQ702
XY70J SOCKET, CRYSTAL: 2 regularly spaced contact
positions, 0.486 in. c to c ea contact, 0.243 in.
from center; cadmium plated phosphor bronze or
beryllium coppe r; Hugh H. Eby part no. 8879
CRYSTAL UNIT, QUARTZ: 38.000 kc
Y701

R760
R761
R762
R763

COLLINS
PART NUMBER

745-1398- 00
705- 7110-00
745-1352- 00
745-1335- 00
745-1440-00
705-7130- 00
705- 7130-00
705- 7130- 00
705- 7130- 00
745- 1352- 00
745-1422- 00
745-1401-00
745-1401-00
259-1597-00

266-3099-00

259- 1596-00

549-1639- 00

367-0020-00
306-2240-00
306-2240- 00
306-0698-00
306-9032-00
306-0587-00
306- 0587- 00
306-2240- 00
306-0951 - 00

306-2240-00
306-0838-00

306-2240-00
306-0587-00
306-0838-00
306-0838-00
306-9033- 00
306-0001 - 00
306-0698- 00
306-2240-00
306-0001-00
306-0698-00
220-1005- 00

352-9903- 00
352- 9902-00
352-9903-00
352-9902-00
352-9903-00
352-9902- 00
352-9902-00
352-9902-00
292-0082-00

289-5392-00

TD-537
786M-l Stereo Generator

R763

R745

R743

R770

R772 R77I R735 R744 R734 R732 R769 R731 R733 R722 R738 R764 R72I

R759
R716
R720
R715

R719
R7l4
R7l2
;;..:;.--'---R7l7
:...J1.- - ; - --R723
_,.,:;.- ....l.---R7l3
""ir---R718
....;.--,---R736
r - -- -R740
-+- - - - R739
R74I
R737
R727
R724
R753
R742
R725
R729

R747

R701

R761
R756

R728

R706

R705 R760 R757 R707 R75I R752 R750 R702 R709 R708 R758

R749

Figure 4-1. 786M-1 Stereo Generator, Rear View, Resistor Location
-~

C734

C735

C733 C732 C726 C725 C723 C72I C724 C722 C720 C730 C7l6 C717 C7l4 C7l2 C7l3 C708 C709 C707
C710
C727

C718

C719

C705
C728

C701

C 703

C702

C704 C706

C715

Figure 4-2. 786M-l Stereo Generator, Rear View, Capacitor Location

19
STEAM POWERED RADIO.COM

TD- 537
786M-1 Stereo Generator

H3

TB70I

XQ705 TB72I

XQ704 T8707 T8702 L703 T8703

L702 XQ702 TB704 L 701 XY70I
TB705

XFL70I

X070I

XQ70s----

18719

X0708

TB7I

TB720

T70I

S702

T87l6

X0707

S 701

H2

1B7I7

HI

S703 TB7l3 TB708 TB7l8 TB7l4

CR702

TB709

Figure 4-3. 786M- 1 Stereo Generator, Rear View, Miscellaneous Parts Location

Q703

R703

L 701

Y70I MPI

0707 0706 0704 0705

L704

FL702
FL70I

FL703
0

0
0

FL704
0

!

FL705

i:lt:, O

0708~

~,

,/

0

:--J__:::~2
""
-=~ -.:c\
l
~

a

~(e~~J702
TP70I S

M70I

0701

R726

0702

S702

R748

F i gure 4-4. 786M-1 Stereo Generator, Front View, Parts Location

20
STEAM POWERED RADIO.COM

R755

TD-537
786M-1 Stereo Generator

SECTION V
ILLUSTRATIONS

38KC
OSCILLATOR
CHOI
2Nl613

Y701

'0JC' I

Iv)
R715
120

iuM6~*
C

MX OUTPU T

r-

C7071+
15UF

/

_,I'

C708
16800

~

R712
33K

<
<

>> >>

R713
5000

L701

I

>

38KC
BUFFER

C710
O,IUF

Q702
2Nl285

"

II

~

R720 <,
SEE NOTE 2

<, R719
12K

'>

R718
33K

'>

'>

R716 <,
4700 >

7

>

::~~
75 BUF
MIN

R IOVU
ADO
L AUDIO
AODIOVU

\

38KC DRIVER
75M I N
19 KC LKD OSC
75MIN

'>
'>

R717
IK

Ri:4~

:m~

'>
>

2700

<

l

R733
150

R732
3300

R734
15K
L703
IOMH

R738
150

:'::: ~6~~

~

-r

+ - C713
20UF

R723
39

>>

~ R722

+1 C712
-120UF

38 KC OSC

7

2~~F

IOMH

R764 <
SEE NOTE 2<

~

l

C724

-"+

"" ¢""
1800

R721
180

38 KC
iSpLATION AMPLIFIER

0703
ZN1613

C716
20UF

I?

C709 ~
l 0.047UF

R714
IOK

38KC
DRIVER

1-

C7291+
20UF

19KC
LOCKED OSCILLATQR

0704
ZN1285

n.::,..------i)l:t--- -,

'(

=
V

'>

R*O<,
4 K

tI

R771
15K

R772 <,
15K ',

R745
4700 >

o.....,_=-------•

::::C
5

'>

C731
120

',

<, R746
> 4700

PILOT
CARRIER

V

R747
> 4700

PHASE

R769
IK

'> R735
'> SEE

R759
39 ,

0705
ZN708

C7ZI
20UF

R743
4700

C723
O.IUF

-r1
+

>
>

C722
20UF

NOTE 2

.-----..-.---~~- < TP 701
R749
33K

:

,LJ

'

\\

-

-120

SPARE

11 o

SPARE

100

SPARE

90

~

115V 60 CPS OUT
11 5 V 60 CPS OUT

4

-

-

'>
'>

...

R710
1330

A

A

M701

R767
5110

>
>

2o

AA

---<>-"./V\,--'
V V

20UF

R768
5110

50

NC

60

0

,___

8

+20VOC IN

9IOo

i,

I

I FL704

S701B

•t

B

, ...

'I

R752
261

-1

70

• 28 voe IN

;>
>

47K

S702

R742
8200

I p ILOT CARRI ER OFF-ON I

R741
287

\

~6:o

-

<1 C
19
- 7 20UF

V

•

C

S701C

1~

I
I

-

0707
2N 1175A

RIGHT
AUDIO
AMPL

C703
30UF
•

>

vv
R751
261

>

<; R707

R702 · >
750

'>

'>

~

-==

3900

C704

R750 <
562 -½

50UF

R708
15K

r0

NOTES,

~

II

>

+

V

R7Z9
464
C737

C706
225UF

•"-

;>

'>

R709
< 3300

R754
IOK

>

--=-

I CR702B

l

I

J.:::

~~

CT51

I

::.j::

·~r

I

I CR702D

:
CARRIER
BALANCE

C736

>R730
1961

2. THE VALUES Of RESISTORS 11720,

?

f!PO

R728

464

R755
250

i3
2
T70I

4

-+-

-<.,_-

~

'
: t
~~- - ---~

I FL.703 I
>

.

~

';, R704
> 3 900
~

C702
50UF

;>

R705

> 15K

r-~•

> R706
3300

I

+ -

R703
10

'>
'>

=
;>

R757
560

R753
IOK

.

CHAN
SEP
L +R AMPL

I

-

1-

-vv..V
R756
619

- -- ----tFL705

1-----•

;, R761
> 1961

464

C705
225UF

I

5

R727

l?y-i-

AMPL

- "+

-===-

K701

0706
2Nll75A

II

R701
750

~

LEFT
AUDIO

C701
30UF

R735 AND R764 ARE DETERMINED
IN PRODUCTION.

AA

I

-I

STEAM POWERED RADIO.COM

LTIIE VALUES OF CAPACITORS
C736 AND C~ ARE DETE~
IN PRODUCTION. IN SOME UNITS,
THESE CAP,ACITORS MAY BE
OMITTED . , ...

IN270

.,.,:-+ I

R726
10

R758
560

>

I

i
...

II
12 o

>>

A
V

o

AUDIO SHIELD

< R739

:. r

::::::

4700

~

R737
47 K

R766
5110

L-------- ---- --------

-

rv:).----+

+

0-

A

R760
12K

0708
2Nl285

C711

I o ....,_

4

AUDIO SHI ELD

I

R762
IK

METER AMPL

R736
560

LEFT AUDIO IN

.•

1 ,/'

Io -

LEFT AUDIO OUT

NC

T

), ~JJ3,::

20 -

)(

...

R711
1330

3 o+--i,-_,f-.....-t-c""13
..5-+--+--+--~V\1v-vv
- - --

'=u

w

----0.. . o~ -- -0~ •

<>+--if-I~ ~ + - - 1 - - - < - - - - < f - - - - - - - - - - - + - - -......- - - - - :

3

NC

r"'\.

:

I

S703C

II

'f i~5 ==
5 o+--+--= ~+---

L EFT AUDIO OUT

z

\ _____ ,-o-. -- - - - - - - -

•

a:

~II)

~

S7038 ' ~ )

' ~ ,

6 o+--,:....,...:==-=4="7"'~~'o~t-it-if--1.......- - - , - - - - - t - - + - - - - - - - - ~

115 V 60 CPS IN

•0

I

RIGHT AUDIO IN

115V 60 CPS IN

...z

S703A

RIGHT AUDIO IN

LEFT AUDIO IN

w iii
..J II)
"'<
•:,:
uu

\,

R765
5110
"'';..
, --C~7~3~2---<.....,f--1.,.....'\vr,vl\r- - - - - - 7 o+--i(-'

LEFT AUDIO IN

w

)

8 o+--------,

AUDIO SHIELDS

w

\

20

STEREO REMOTE CONTROL

'>
'>

I-~
I

\

TB701
SPARE

IOK

PILOT
CARRIER
LEVEL

\

METER

R748

cm J:I c~J~Jt
1
I

R725 c

~=-f :

737

~: I CR702C

L.. . --"4./'~v!._,....
_ __.,,:--~-~-N-t_~~r•~_
-_-_-_- -C736 ( R724
;> 1961

I
\

Figure 5-1. 786M-l Stereo Generator, Schematic Diagram

21/ 22

B830-1 250-Watt FM Power Amplifier

523-0755596-101438

~~

STEAM POWERED RADIO.COM

Unit Instructions

\

TD-538

\

523-0755596- JO J 43 8
\

1 February 1962
1st Revision, 1 Jan uary 1967

~

COLLINS

~
•
•
•
unit
1nstru
ct1ons

B830-1
250-Watt FM

Power Amplifier
© Collins Radio Company 1962, 1967

STEAM POWERED RADIO.COM

Collins Radio Company

I Dallas,

Texas

Printed in U . S. A.

table of contents
Page

Section
1

GENERAL DESCRIPTION .

1-1

1. 1

1-1
1-1
1-1
1-1
1-1
1-1
1-2
1-2
1-2
1-2
1-2
1-2

1. 2
1. 3
1. 3. 1
1. 3. 2
1. 4
1. 5
1. 6
1. 7
1. 7. 1
1. 7. 2
1. 8

Purpose of Instruction Book
Purpose of Equipment .
Description of Equipment .
Physical Description
Electrical Description .
Equipment Supplied
Equipment Required but Not Supplied
Accessory Equipment .
Equipment Specifications
Mechanical
Electrical
Tube and Semiconductor Complement

PRINCIPLES OF OPERATION

2- 1

2.1
General
2. 1. 1
Control Circuits
Power Amplifier Circuits .
2. 1. 2
2. 2
Control Functions

2-1
2-1
2-2
2-7

MAINTENANCE .

3-1

3. 1
General
3.2
Preventive Maintenance
Air Filter Cleaning .
3. 2. 1
PA Tube Cleaning
3. 2. 2
3. 2. 2.1
PA Tube Removal
Inspection
3. 2. 3
3.2.4
Lubrication
Tube Maintenance
3. 2. 5
Troubleshooting.
3.3
3. 4
Cable Chart .

3- 1
3-1
3-1
3-1
3-2
3-2
3-2
3-2
3-2
3-2

4

PARTS LIST .

4-1

5

ILLUSTRATIONS

2

3

5-1/ 5-2

list of illustrations
Page

Figure
1-1
2-1
2-2

Overall View, B830- 1 250-Watt FM Power Amplifier (B502-187-Pb).
Block Diagram, B830-1 250-Watt FM Power Amplifier (B502-188-4).
Control Circuits Simplified Diagram, B830-1 250- Watt FM Power
Amplifier (B502-189-6) .

2-3

Power Amplifier Simplified Diagram, B830-1 250-Watt FM Power
Amplifier

STEAM POWERED RADIO.COM

(B502-190-6)

.

1-0
2-2
2-3/ 2-4
2-5/ 2-6

list of illustrations (cont)
Page

Figure
2-4
4- 1

5-1

Control Locations B830- 1 250- Watt FM Power Amplifier (B502- 186- Pb).
B830- 1 250- Watt FM Power Amplifier (B502- 179-Pb) {B502-181- Pb) {B502-184- Pb)
{B502- 195- Pb) (B502-183- Pb) {B502-193-Pb) {B502-185-Pb) (B502- 194- Pb)
(B502-196- Pb) (B502-155-Pb) {B502- 180-Pb) .
.
Overall Schematic, B830-1 250-Watt FM Power Amplifier (B502- 178- 6)

2-7

4- 2
5-3/5-4

list of tables
Page

Table
1- 1

1- 2
1-3
1-4
1- 5
3- 1
3- 2

Associated Equipment Instruction Books.
Equipment Supplied .
Equipment Requir ed but Not Supplied
Accessory Equipment .
Tube and Semiconductor Complement
Typical Meter Indications
From- To Information .

ii
STEAM POWERED RADIO.COM

1-2
1-2
1-2
1-2
1- 2
3- 3
3- 3

general description

•

Figure 1-1.

1-0
STEAM POWERED RADIO.COM

-- --.

Overall View, B830-1 250-Watt FM Power Amplifier

section

1

general descrip tion
1.1

PURPOSE OF INSTRUCTION BOOK.

Unit Instructions TD-538 provides information about
B830-1 250-Watt FM Power Amplifier. Information
which is furnished covers a general description of the
equipment, principles of operation, maintenance procedures, and a parts list.
1.2

PURPOSE OF EQUIPMEN T.

The B830-l 250-Watt FM Power Amplifier can be used
for continuous monaural or multiplex and SCA FM
broadcast service on a single frequency in the range
fr om 88 to 108 megacycles with an exciter input of
10 watts and an output power of 250 watts.
The B830-1 will drive the 830F 10-KW FM Power
Amplifier or the 830E 5-KW FM Power Amplifier to
full output.
1.3
1.3.1

DESCRIPTIO N OF EQUIPMEN T.
PHYSICAL DESCRIPTIO N.

The B830-l 250-Watt FM Power Amplifier, s hown in
figure 1-1, is contained in a single cabinet that is 38
inches wide, 76 inches high, 27 inches deep, and weighs
approximate ly 596 pounds. All B830-1 operating controls are l ocated behind the doors on the front of the
cabinet. The filament and plate on-off controls and
four monitoring meters are located at the top front of
the cabinet. The meters may be observed easily while
operating the tuning controls. The B830-1 uses three
tubes, all of which are accessible from the fr ont of the
transmitter. The bottom front of the B830-1 cabinet
is removable to allow access to components on the
bottom of the inside panel.
Large doors at the upper rear of the cabinet allow
access to the upper part of the B830-1 for servicing
and maintenance . Operating personnel are protected
by both electrical and mechanical interlocks on the
rear doors and panel. These interlocks remove the
B830-l plate voltage and ground the high-volt~ge
circuits when the doors are opened or the panel is
removed. The power amplifier plate-tuning cavity is
located in an interlocked compartmen t at the front of
the B830- 1.

Inside the B830-1, heavy iron-core components are at
the bottom of the cabinet. A standard 19-inch rack is
provided for mounting the 10-watt exciter within the
confines of the B830-1. Room also is provided on the
standard 19-inch rack for the mounting of SCA
generators. An optional harmonic filter, which can be
connected to the B830-1 output, is suspended from the
top of the cabinet.
Cooling air for the B830-l is drawn through a
permanent air filter at the rear of the cabinet by a
low-speed, high-volume fan and exhausted through a
shielded opening in the top of the cabinet. A single
pressure blower supplies cooling air directly to the
power amplifier tube.
1.3.2

ELECTRICA L DESCRIPTIO N.

The B830-1 250-Watt FM Power Amplifier consists of
a single, air-cooled, power amplifier tube capable of
being driven to full power by a 10-watt exciter. All
associated power supply and control circuitry is included for operation of the B830-1. The B830- 1 rf
input impedance is 50 ohms nominal, unbalanced. The
B830-l output power is at least 250 watts over the
frequency range of 88 to 108 megahertz into a 50- ohm
load, with an swr not exceeding 2: 1.
Line power input required is 50 or 60 hertz, single
phase, with primary taps on all power transforme rs
to compensate for line voltage variations from 200 to
250 volts. (For 50-hz operation, a special blower
is available on request.) Circuit breakers in the input
side of the line are provided for primary circuit
protection. The control circuits and the final amplifier filament are fused. A time delay relay provides protection of the power amplifier tube during
warmup. Remote control can be exercised over
filament-on, filament- off, plate-on, and plate-off
functions of the power amplifier. Instruction books
covering the excite rs and power amplifiers used in
conjunction with B830-1 250-Watt FM P ower Amplifier are listed in table 1-1.
1.4

EQUIPMEN T SUPPLIED.

Tabl e 1- 2 lists equipment that is supplied as part of
B830- l 250-Watt FM Power Amplifier.

1-1
STEAM POWERED RADIO.COM

general description

TABLE 1-1.

ASSOCIATED EQUIPMENT
INSTRUCTION BOOKS

ASSOCIATED
EQUIPMENT

INSTRUCTION BOOK
NUMBER

A830-2 10 W Wide-Band
FM Broadcast Exciter

TD-536
523-0755303

786M-1 Stereo
Generator

TD-537
523-0755304

E830-1 5-Kw FM Power
Amplifier

TD-539
523-0755306

F830-l 10-Kw FM
Power Amplifier

TD-580
523-0755345

TABLE 1-2.

Maximum Power Requirements:
730 watts
Rf Input Power:
10 watts nominal
Input Impedance:
50 ohms nominal, unbalanced
Power Output:
250 watts nominal
Output Impedance:
50 ohms, resistive, unbalanced
Maximum swr 2:1
Frequency Range:
88 to 108 megahertz
Exact operating frequency determined by fre quency exciter (80 to 100 MHz available on
special request) .

EQUIPMENT SUPPLIED

EQUIPMENT

COLLINS
PART NUMBER

B830-l 250-Watt FM Power
Amplifier

549-2008-000

1.8

TUBE AND SEMICONDUCTOR COMPLEMENT.

Table 1-5 lists the tube and semiconductor complement supplied as part of B830-l 250-Watt FM Power
Amplifier.

TABLE 1-3.
1.5

EQUIPMENT REQUIRED BUT NOT SUPPLIED.

Table 1-3 lists equipment that is required for operation of B830-l 250-Watt FM Power Amplifier but not
supplied as part of the power amplifier.
1.6

ACCESSORY EQUIPMENT.

Table 1-4 lists accessory equipment that is available
for use with B830-l 250-Watt FM Power Amplifier.
1.7

EQUIPMENT REQUIRED BUT
NOT SUPPLIED
COLLINS
PART NUMBER

EQUIPMENT
A830-2 10 W Wide-Band FM
Broadcast Exciter

522-2714-000

786M-l Stereo Generator (for use
with A830-2 only) (optional)

522-2914-000

EQUIPMENT SPECIFICATIONS.

1.7.1

MECHANICAL.

TABLE 1-4.

Weight:
596 pounds maximum
Size:
38 inches wide, 76 inches high, 27 inches deep
Ventilation:
One ventilating fan, one blower

ACCESSORY EQUIPMENT
COLLINS
PART NUMBER

EQUIPMENT
250-Watt/ 1-Kw Harmonic Filter
(used only if the B830-1 is fed
directly to an antenna and not to
a higher power amplifier)

549-2010-000

Ambient Temperature Range:
+l0°C (50°F) to +45°C (113°F)
Ambient Humidity Range:
Up to 95 percent relative humidity
Altitude:
Up to 6000 feet. (Blower for higher altitude available on special request.)
1.7.2

ELECTRICAL.

Power Source:
200 to 250 volts, 50 or 60 Hz, single phase (50Hz blower available on special request).
1-2
STEAM POWERED RADIO.COM

TABLE 1-5.

QUANTITY

TUBE AND SEMICONDUCTOR
COMPLEMENT
TYPE

FUNCTION

1

4CX250B/ 7203

Rf power amplifier

2

OD3

Voltage regulation

2

4JA421EH20AB1

Plate and scre en
voltage rectifiers

section

2

principles of operation
2.1

GENERAL.

The B830-1 250-Watt FM Power Amplifier consists of
a power amplifier and associated control circuitry for
the amplification of 10 watts of exciter drive to 250
watts of rf power. The B830-l output can drive a
higher power amplifier or can be fed through a harmonic filter to an antenna.
Refer to figure 2-1. The 230 volts ac is fed to a
control circuit power transformer which reduces the
input voltage to 115 volts ac for use by the blower and
control circuits. A second transformer located within
the control circuitry reduces the 115 volts ac to 6. 3
volts for use by the power amplifier filament. The
230 volts ac also is fed to a transformer which
supplies the power amplifier plate and screen voltages. The primary power input to the plate power
supply is controlled by the plate contactor.
The control circuits provide cabinet interlocks for
protection of personnel from all high voltage, local or
remote filament-on and filament-off controls, local or
remote plate-on and plate-off controls, and time
delay to prevent the application of high voltage before
the power amplifier filament has heated sufficiently.
Provisions also are available within the control circuitry for connection to the control circuitry of a
higher power amplifier. The higher power amplifier
will then control the B830-l plate and filamentpower.
Exciter input power is applied directly to the power
amplifier where it is raised to 250 watts of rf power.
The power amplifier consists of a forced-air-cooled
ceramic tetrode, V201. The plate of V201 is connected to a tuned cavity ( ~ coaxial line resonator).
The output from the tuned cavity then can be fed to a
higher power amplifier, or to a harmonic filter and
antenna if higher power amplification is not necessary.
A sample of the power amplifier output is taken from
the plate tuned cavity for monitoring purposes.
Metering circuits are provided for the power amplifier
plate current and voltage, screen current and voltage,
grid current, and output power.
2.1.1

CONTROL CIRCUITS.

Refer to figure 2-2. The primary purpose of the control circuitry is to provide filament and plate on and

off control. The power amplifier filament is turned on
in the following manner: When momentary FILAMENT
ON switch S112 is pressed, a ground is placed on
filament control relay K301. As 115 volts ac is
present on terminal 2 of relay K301 from 115-volt ac
supply transformer T301 the filament control relay
will be energized. This closes contacts 3 and 4, holding the relay in the energized position after momentary
FILAMENT ON switch S112 is released. The green
filament indicator lamp, DS301, will light. When filament control relay K301 is energized, relay contacts
6 and 7 will close, starting the cabinet fan and power
amplifier blower B301 and supplying 115 volts ac to
the 10-watt exciter. When blower B301 comes up to
speed, air interlock switch S314 will close, applying
115 volts ac to filament transformer T302 and time
delay relay K303. After approximately 30 seconds
(time for power amplifier filament V201 to warm up),
time delay relay K303 will be energized, closing
contacts 3 and 4, supplying 115 volts ac to plate
contactor relay K304.
The plate supply now can be turned on by pressing
the momentary PLATE ON switch (providing all
interlocks are closed). Pressing the momentary
PLATE ON switch places a ground on plate control
relay K302. Relay K302 then will energize, closing
contacts 3 and 4, holding K302 in the energized
position. Contacts 9 and 10 will also close, energizing
plate contactor K304 and lighting the red plate
indicator lamp. When the plate contactor closes, the
primary ac supply will be applied to plate and screen
supply transformer T303. The plate power supply then
will furnish approximately 2000 volts de to power
amplifier tube V201.
Momentary FILAMENT OFF switch S111 removes
power from the control and power amplifier circuits.
It accomplishes this by opening the 115-volt ac lead
to filament control relay K301, and plate control relay
K302. This deenergizes plate contactor K304 and
blower interlock S314, removing filament, plate, and
screen voltages. The time delay will immediately
reset for the next turn- on procedure.
Momentary PLATE OFF switch S114 removes only
plate and screen voltage from power amplifier V201.
This is accomplished by momentarily opening the
ground lead of plate control relay K302, which
deenergizes plate contactor K304, removing 230-volt
ac power from the plate supply.
2-1

STEAM POWERED RADIO.COM

principles of operation
MONITOR
OUTPUT

\I

230V 60 HZ ------4

PLATE
CONTACTOR

PLATE AND
SCREEN
HIGH VOLTAGE
SUPPLY

88-I0SMHZ 250W
POWER
AMPLIFIER

OUTPUT
TO HARMONIC
FILTER OR HIGHER
POWER AMPLIFIER

1

POWER
AMPLIFIER
INPUT

AUXILIARY
POWER
SUPPLY

88-I0SMHZ
IOWATTS

REMOTE
CONTROL---EQUIPMENT

CONTROL
CIRCUITS

Figure 2-1.

L-------TO EXCITER
L-------TO HIGHER POWER AMPLIFIER

Block Diagram, B830-1 250-Watt FM Power Amplifier

Plate overload protection is provided by overload
relay K305. As the plate current increases, the voltage
across R303 will increase until overload relay K305
energizes, opening the ground lead of· plate control
relay K302, and removing plate voltage. Potentiometer R304 adjusts the point at which excess plate
current will activate overload relay K305.
2.1.2

POWER AMPLIFIER CIRCUITS.

Refer to figure 2-3. The power amplifier consists of
a forced-air-cooled tetrode amplifier, working into a
tuned cavity over the standard frequency-modulated
broadcast band of 88 to 108 megahertz.
The power amplifier plate and screen voltages are
obtained from a full-wave, semiconductor, rectifier
circuit. Transformer T303 increases the 200- to
250-volt, single-phase, 50- or 60-Hz primary input
to approximately 4000 volts rms across terminals 8
and 10 {T303 secondary winding, 2000 volts each side
of center tap). The primary winding of transformer
T303 has six adjustable taps to compensate for line
voltages from 200 to 250 volts. The output voltage
from the secondary winding of T303 is fed to a
conventional full-wave rectifier consisting of diodes
CR301 and CR302, inductors L301 and L302, and
capacitors C301 and C302. Resistor R320 and capacitors C303 and C304 form a transient suppressor
which eliminates the transient voltages formed when
power is first applied to transformer T303, and when
power is switched off. The 2000-volt de output from
the power supply is fed through P.A. PLATE CURRENT meter M303 through an rf filter consisting of
C210, C217, and L202 to the plate of V201. Plate
voltage and plate current are read directly from
P.A. PLATE VOLTAGE meter M302 and P.A. PLATE
CURRENT meter M303 respectively.

2-2
STEAM POWERED RADIO.COM

The screen voltage is obtained from the 2000-volt
plate supply. The plate supply is fed to a combination
bleeder resistor and voltage divider consisting of
resistors R305, R308, and R309. Voltage regulator
tubes V301 and V302 are placed in parallel with
resistors R308 and R309 to form a regulated 300-volt
supply which is supplied to the screen grid of V201.
Capacitor C212 shunts any rf energy present on the
screen grid to ground.
Power amplifier V201 is a cathode and grid leak
biased, class C operated tetrode . The control grid
circuit of V201 consists of a parallel-tuned resonant
tank circuit (L20 1 and C213) with swamping resistor
R201 placed in parallel to provide a low- impedance,
broadband load to the control grid. Control grid
tuning is accomplished by capacitor C213.
The cathode circuit of V201 contains an output power
adjusting potentiometer which raises or lowers the
cathode resistance. As V201 is cathode biased, adjusting POWER OUTPUT ADJUST potentiometer R317
changes the cathode bias, as well as the screen
potential, which controls the power output of V201.
Capacitors C201 through C204 form the cathode
bypass.
The plate cavity is formed by a short section of
coaxial transmission line resonating with the plate
capacity of V201 and plate tuning capacitor C209.
The coaxial transmission line is roughly tuned initially
by adjusting a shorting plate which lengthens or
shortens the coaxial transmission line. Final plate
tuning is accomplished by C209. The output coupling
network formed by C208 and L203 l.s connected to the
plate transmission line adjacent to the plate of V201
for correct impedance matching. Inductance L203
and capacitor C209 act as an L-section, low-pass

principles of operation
'REMOTE RESE"il
--ICSUPPLIED WITHI
REMOTE CONT)

r- I

I

I
I
J

CB301
111
200 TO 230 VAC{
60HZ

_

-

TB306

I
I

TB302

2
-

2= - - - - + - - --

.....__,f----"-+--'\r---0

REMOTE CIRCUIT BREAKER OFF
2

fo--+=
_l_

3

3

'---1----1-----+.-_-'
_ _-+-0

_,I;

,

'------R-E_M
_o_T_E_c_1R_c_u_1T_BR_E_A_K_E_R_o_N
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _-'--- - - - - - - - - - =5

6

TO PA

iI L4_ _ _~

3

4

L _ _ _J

PLATE

ANO

• , •

} SCREEN SUPPLY
'"'---1-----

I

I

I
I
I
I
I
I

5

I

2

3

3

4

'-'--t------+--------------;!,~.

N

--

GER

•
M301

Figure 4-1.

M302

M303

M304

R321

B830- l 250- Watt FM Power Amplifier (Sheet 2 of 12)

4-3
STEAM POWERED RADIO.COM

parts list

MP301

MP313
L203
MP303
MP304

DETAIL A

~·

_:..:,__:..
• --;---MP305

~MP302

Figure 4- 1.
4- 4
STEAM POWERED RADIO.COM

B830- 1 250-Watt FM Power Amplifier (Sheet 3 of 12)

parts list

E201

'C207

C209

S201

C202
I

I

I

C205

C216

C204

I

R202

R204

C213

S202

C214

•,)Vilt·I

Figure 4-1.

B830- 1 250- Watt FM Power Amplifier (Sheet 4 of 12)

4- 5
STEAM POWERED RADIO.COM

parts list

E306

S310

S313

DETAIL C

S312

TB307

S309

MP311

TB308

TB305

DETAI L B

TB301

TB304

"

Figure 4-1.

4-6
STEAM POWERED RADIO.COM

B830- l 250-Watt FM Power Amplifier (Sheet 5 of 12)

parts list

R310

R311

R312

TB308

-~

Figure 4 - 1.

B830- l 250- Watt FM Power Amplifier (Sheet 6 of 12)

4-7
STEAM POWERED RADIO.COM

parts list

P307

DC301

E313
S308

1·1Riili

Figure 4-1.
4- 8
STEAM POWERED RADIO.COM

B830- 1 250- Watt FM Power Amplifier (Sheet 7 of 12)

parts list

K301

E322
/

K302

K303
R304

P308
K305

J203
K304

,1202

R323
P303

l·hOll·I

F igur e 4- 1.

B830- 1 250- Watt FM Powe r Amplifier (Sheet 8 of 12)

4-9
STEAM POWERED RADIO.COM

parts list

E314

C206

C219

C218

J201

I

I

B301
TB309

E317

i·1Uiill

Figure 4-1.
4- 10
STEAM POWERED RADIO.COM

B830- l 250-Watt FM Power Amplifier (Sheet 9 of 12)

parts list

S302

XV302

E316

R308

R309

XV301

I
E303

C304
C303
E302

E311

E318
R320
CR302
CR301
E301
E309
R306
L302

R303
E315
L301

T301

T303
E310

l·)U-iill

Figure 4-1.

B830-1 250-Wa tt FM Power Amplifi er (Sheet 10 of 12)
4-11

STEAM POWERED RADIO.COM

parts list

T304

TB324

S311

•

Z301
FOR
OPTIONAL
REMOTE
CONTROL
EQUIPMENT

1

TB333

•
TB334

Z302
FOR
OPTIONA L
REMOTE
CONTROL
EQUIPME NT

TB302

••
TB303

l·)UJilii

Figure 4-1.

4-12
STEAM POWERED RADIO.COM

B830- 1 250-Watt FM Power Amplifier (Sheet 11 of 12)

pa rts lis t

Fi gu re 4- 1.

STEAM POWERED RADIO.COM

B8 30 -1 25 0- W att
FM Po we r Am pl ifi
er (S he et 12 of 12)

4- 13

parts list

SYMBOL

DESCRIPTION

MANUFACTURER'S
PART NUMBER

MFR
CODE

B830-1 250-WATT FM POWER
AMPLIFIER
8301
8302
C201
C202
THROUGH
C205
C206
C207
C208

C209
C210
C211
C212
C213
C214
C215
C216
C217
C218
C219
C220
C301
C302
C303

FAN, CENTRIFUGAL
115 VAC, 60 CPS SINGLE
PHASE
MOTOR, ALTERNATING CURRENT
230 VOLTS, 50/60 CPS, 1550
RPM
CAPACITOR, fXO, CERAMIC
0.02 UF, PLUS 100% MINUS
2oi, 500 vocw

COLLINS
PART NUMBER
549-2008-000

2C6010

16327

009-1576-000

5KSP51Cll 7

24446

230-:-0164-000

33C2

019,39

913-2142-000

327-029X5T0102Z

72982

913-1292-000

OA-858-003

71590

913-0101-000

SAME AS C20l
CAPACITOR, FXD, CERAMIC
1000 UUF, PLUS 801 MINUS
20%, 500 vocw
CAPACITOR, FXD, CERAMIC
1000 UUF, 2oi TOL, 5000
VDCW
PLATE, CAPACITOR
ALUMINUM, 0.063 INCHES
THICK, 2.625 INCHES DIA,
2.625 INCHES WIDE
CAPACITOR, VARIABLE, AIR
4.5 UUF MIN TO 9.5 UUF
MAX, 7000 VOL TS
SAME AS C207
SAME AS C206
PART OF XV2 0 1
CAPACITOR, VARIABLE, AIR
3.9 UUF MIN TO 50 UUF MAX
SAME AS C20 6
SAME AS C206
SAME AS C207
SAME AS C207
SAM E AS C206
SAME AS C206
CAPACITOR, FXD, PLASTIC
35 UUF, 1000 VOCW
CAPACITOR, FXO, PAPE R
4UF, 10% TOL, 4000 VOCW
SAME AS C301
CAPACITOR, FXO, CERAMIC
0.002 UF, 20% TOL, 6000

549-2059-002

165-8-2

74970

922-0570-000

11726-244

80583

922-0016-000

549-2126-002
P47484

56289

930-0705-000

OAl 72-087CP

71590

913-3540-000

850-001

71590

913-4253-000

857-332

7159-0

913-1425-000

CK63 AW103M

81349

913-1188-000

vocw

C304
C305
C306
C307

C30 8
C309
C310
THROUGH
C313
C314
C315

C316

SAME AS C30 3
CAPACITOR, FXO, CERAMIC
25 UUF, 10% TOL, 2500 VOCW
PART OF HARMONIC FILTER.
SAM E AS C305
CAPACITOR, FXD, CERAMIC
33 UUF, 10% TOL, 15,000
VDCW. PART OF HARMONIC
FILTER.
SAM E AS C305-PART OF
HARMONIC F ILTER.
SAME AS C30 5-PART OF
HARMONIC F ILT ER.
SAM E AS C30 5
CAPACITOR, FXO, CE RAMIC
10,000 UUF, 2 0% TOL, 500
VDCW
SAM E AS C314
SAME AS C314

4-14
STEAM POWERED RADIO.COM

parts list

-

~

DESCRIPTION

SYMBOL

C830l

CIRCUIT BREAKER

MANUFACTURER'S
PART NUMBER

MFR
CODE

COLLINS
PART NUMBER

2263S

74193

260-0239-000

4JA421EH2CA81

24446

353-1794-000

IN3016B
IN963A
576KM

07688
07688
16731

353-3220-000

3S6-5

24446

262-3310-000

SK-626

06980

220-1466-000

75Al01GRN

72765

262-0258-000

75Al01RED

72765

2 62- 02 5 9-000

F03A250V5AS

813"t9

548-3584-003
548-3586-003
548- 3588-003
548-3590-003
549- 2ll3-004
264-0361-000

313004

75915

264-0217-000

UG1094U

80058

357-9183-000

UG58AU

8005 8

357-9003- 000

UG-1187/U

80058

357-9476-000

100- 83000C-75

94375

357-9248-000

83-3544

04221

970-1933- 000

50-AMPCURRENT RATIN~

CR30l
CR302
CR303
THROUGH
CR386
CR387
CR388
DC301
DS301
OS302
. E201
E301
E302
E303
E304
E305
E306
E307
E308
E309
E310
E311

E312
E313
E314
E315
E316
E317
E3 18
E319
E320
E321
E322
E323
E324

SEMICONDUCTOR DEVICE, DIODE
SAME AS CR301
NOT USED
SEMICONDUCTOR DEVICE, DIODE
SEMICONDUCTOR DEVICE, DIODE
COUPLER UNIT
DOUBLE COUPLER, SO OHMS
IMPEDANCE
LAMP, BULB
0.027 AMP, 125 VOL TS
SAME AS DS301
CHIMNEY, AIR SOCKET SYSTEM
CERAMIC
TERM IN AL LUG
INSULATOR, STANDOFF
INSULATOR, ST ANDOFF
INSULAT OR , STANDOFF
NOT USED
INSULATOR, STANDOFF
INSULATOR, STANDOFF
INSULATOR, STANDOFF
TERMINAL LUG
GROUND LUG
TERMINAL LUG
TERMINAL LUG
TERMINAL LUG
TERMINAL LUG
TERMINAL LU G
TERMINAL LUG
GROUND LUG
TERMINAL LUG
NOT USED
NOT USED
NOT USED
TERMINAL LU G
LENS, INDICATOR
GKEEN
LENS, INDIC ATOR

353-3121-000
277-0156-000

RED

J304
J305

PUSHBUTTON, FILAMENT OFF
PUSHBUTTON, FILAMENT ON
PUSHBUTTON, PLATE ON
PUSHBUTTON, PLATE OFF
SHIELD, RADIO FREQUENCY
FUSE, CAR TR IOGE
2 50 VOLTS, 5.0 AMPS
SAME AS F301
FUSE, CARTRI DGE
125 VOLTS, 4 AMPS
CONNEC TOR, ELECTRICAL
1 CONTACT
CONNECTOR, ELECTRICAL
l CONTACT
SAME AS J201
SAME AS J201-PART OF
HARMONIC FILTER.
SAME AS J201-PART OF
HARMONIC FILTER.
CONNECTOR, cLECTR ICAL
500 VDCW, 50 OHMS
IMPEDANCE
CONNECTOR, ELECTRICAL
SAME AS J30 4

K301

Rc:LAY, ARMATURE

E325
E326
E327
E328
E329
F301
F302
F303
J201
J202
J203
J30l
J302
J303

/'.

4-15
STEAM POWERED RADIO.COM

parts list

SYMBOL

K302
K303
K304
K305
L201
L202
L203
L301
L302
M301
M302
M303
M304
MP301
MP302
THROUGH
MP30 5
MP306
MP307
MP308
MP309
MP310
MP311
MP312
MP313
MP314
MP315
MP316
MP317
MP318
MP319
MP3 20
MP321
MP322
P301
P302
P303
P304
P305

DESCRIPTION

115 VOLTS AC, 330 OHMS
RESISTANCE
SAME AS K301
RELAY, SWITCH
20 AMPS, 60 CPS, 20 VOLTS
RELAY, ARMATURE
2 CONTACTS
Rl:LAY, ARMATURE
SILVER, 10 OHMS
RESISTANCE, 10% TOL
NOT USED
COIL, RADIO FREQUENCY
4.7 UH, lOi TOL, 0.60 OHMS
RESISTANCE
COIL, RADIO FREQUENCY
CHOKE
10 H, 90 OHMS, 0.350 AMPS
SAME AS L301
MEHR
100 OHMS, PLUS 5% MINUS
10% METER RESISTANCE
METER
COIL TYPE, MOVING
METER
COIL TYPE, MOVING
METER
COIL TYPE, MOVING
KNOB
BLACK PHENOLIC

MANUFACTURER'S
PART NUMBER

MFR
CODE

COLLINS
PART NUMBER

DA2102-002-12060

27780

402-0126-000

702LBOD92

01121

405-0674-000

95062

78277

408-1114-000

LT7Kl94

81349

549-2132-002
240-0178-000

El2321

-80008

549-2133-002
668-0014-000

56-0443-0000

80145

458-0649-000

56-0383-0000

80145

458-0640-000

56-7733-0000

80145

458-0639-000

56-4922-0000

80145

458-0638-000
546-1293-003

SAME AS MP301
KNOB
BLACK PHENOL IC
CONTACT ASSY
INTERLOCK SWITCH
SAME AS MP30 7
LATCH, MAGNETIC
ALUM INUM STRIKER PLATE,
STEEL FERRITE MAGNET
SAME AS MP309
ROD ASSEMBLY, SHORTING
BRASS, PLASTIC HANDLE
24.938 INCHES LONG
CATCH, HEAVY DUTY
STEF. L, CADMIUM PLATE

546-1294-003
N4050

85107

260-4050-000

ADPLlOODCSTl

84792

015-0899-000

549-2186-003
4-2-57

14608

015-0005-000

61-380 CAC-1

42689

549-2128-002
015-1398-000

40F3687-l

01930

2105

74887

1SAME AS MP30,6

SHAFT, STRAIGHT
LATCH, TOUCH RELEASE
STEEL, CADMIUM PLATE
NOT USED
CATCH, DOOR
WINDOW, METtR OBSERVATION
GLASS, 3/16 INCHES THICK
PLATE, SWITCH ACTUATOR
COUPLING
BRASS
SAM E AS MP301
FILT ER, AIR
STEEL FRAM E
CONNECTOR, ELECTRICAL
1 CONTACT
SAME AS P301
CONNECTOR, ELECTRICAL
1 CONTACT-PART OF
EXCITATION INPUT.
SAME AS P303
CONNECTOR
USED WITH HARMONIC FILTER.

4-16
STEAM POWERED RADIO.COM

015- 4090- 000
548-3567-002
549-2054-002
015-0257-000
009-1069-000

MS35168-8 8E

96906

357-9292-000

UG1185A/U

81349

357-9326-000

parts list

SYMBOL

P306
P307
P308
P309
R201
R202
R203
R204
R301
R302
R303
R304
R305
R306
R307
R308
R309
R310
R311
R312
R313
R314
R315
R316
R317
R318
R319
R320
R321
R322
R323
R324
R325
R326
THROUGH
R420
R421
R422
Slll

DESCRIPTION

SAME AS P305
SAME AS P301
NOT USED
CONNECTOR
2 CONTACTS-USED WITH
CABINET FAN
RESISTOR, FXD, COMPOSITION
2700 OHMS, 10% TOL, 2
WATTS
RESISTOR, FXD, COMPOSITION
3300 OHMS, 10% TOL, 2
W

parts list

.,,,-----.,

.

SYMBOL

76005
76487

76854
77554
78277
80008
80058
80145
80147
80583
81349

81350

81483

81487

82104

82877
84792
85107
90211
,,,.--..._

91637
91929

DESCRIPTION

MANUFACTURER'S
PART NUMBER

MFR
CODE

COLLINS
PART NUMBER

800 E NORTHWEST HWY
DES PL AINES, ILL.
ZIP CODE 60016
LORD MFG. CO.
1635 WEST 12TH STREET
ERIE, PA
MILLEN JAMES MFG CO. INC.
150 EXCHANGE ST.
MALDEN, MASS.
ZIP CODE 02148
OAK MFG. CO.
SOUTH MAIN
CRYSTAL LAKE, ILL.
REDMAN TRAILER CO.
ALMA, MICH.
SIGMA I~STRUMENTS INC.
170 PEARL ST.
SOUTH BRAINTREE, MASS.
ELECTRO ENGINEERING WORKS
OAKLAND, CALIF.
JOINT ELECTRONIC TYPE
DESIGNATION SYSTEM
ASSEMBLY PRODUCTS INC.
7100 ,1 ILSON MILLS ROAD
CHES TERLAND, OHIO
BIGGS STEEL FOUNDRY A'4D
FABRICATING CO.
AKRON, OHIO
HAMMARLUND CO. INC
NEW YORK, N.Y •
MILITARY SPECIFICATIO"S
PROMULGATED BY
STANDARDIZATION DIVISION
DIRECTORATE OF LOGISTIC
SERVICES DSA
JOINT ARMY-NAVY
SPECIFICATIONS
PROMULGATED BY
STA.. DARDIZATION DIVISION
DIRECTORATE OF LOGISTIC
SERVICES 0SA
INTERNATIONAL RECTIFIER
CORP.
1523 EAST GRAND AVE.
El SEGUNDO, CALIF.
SQUARE D CO.
INDUSTRIAL CONTROLLER
DIVISION
4041 NORTH RICHARDS ST.
MILWAUKEE, WIS.
STANDARD GRIGSBY INC.
2085 N HAWTHORNE AVENUE
MELROSE PARK, ILL.
ZIP CODE 60160
ROTRON MFG. CO. INC.
7-9 HASBROUCK LANE
WOODSTOCK, N.Y •
HEPPNER MFG. CO.
P.O. BOX Q
ROUND LAKE, ILL.
NEPTUNE ELECTRONICS CO.
30 WEST 15TH STREET
NEW YORK, N.Y.
SQUARED CO.
9405 RIVER
CHICAGO, Ill
DALE ELECTRONICS INC.
COLUMBUS, NEBR
HONEYWELL INC.-MICRO SWITCH

4-21
STEAM POWERED RADIO.COM

parts list

DESCRIPTION

SYMBOL

92702

91t310

94375
96214
96906
97488

97965

DIVISION
FREEPORT t ILL.
IMC HAGN ET ICS CORP .
EASTERN DIVISION
570 HAIN STREET
WESTBURY LONG ISLANO, N.Y.
TRU-OHM PRODUCTS
MEMCOR COMPONETS DIVISION
P.O. BOX 890
HUNTINGTON, IND.
AUTOMATIC METAL PRODUCTS co.
315 BERRY
BROJKLYN, N.Y.
TEXAS INSTRUMENTS INC.
APPARATUS DIVISION
DALLAS, TEXAS
MILITARY STANDARD
PROMULGATED BY STANOIZATION DIVISION DIRECTORATE
UNITED STATES RUBBER CO.
OF LOGISTIC SERVICES DSA
CONSUMER INDUSTRIAL AND
PLASTICS PRODUCTS DIVISION
CHICAGO, ILL.
STANCON ELECTRONICS HC
CHICAGO, I LL .

4- 22
STEAM POWERED RADIO.COM

MANUFACTURER' S
PART NUMBER

MFR
CODE

COLLINS
PART NUMBER

-~

section

5·

illustrations

5-1/5-2
STEAM POWERED RADIO.COM

illustrations

•

TO EXCITER

.

TO REMOTE CONTROL

...... z

u.
u.

Oo

0

~

0

0

u.

I!:' ::; is

- :5

UJW...J_j

~ ~

-

...w

z

0

:!:

~

a::w~ f58~a::~
w ... <(
,-4,-.

z

0

...w

~~~

<(
_J

'-' '-'
<(
> >

<(

~~~ ~ j

::i:50

~ ~

<.n [/) i... LI.. Q. '-' 0..

~8

9

.,
I

I?

I PART Of
TB:303

I

"' "'
)

I)

~

o

'-'
3 6 7
)

I
I

TB334

I

I
I

I
I

ON- OF F
\SEE NOTE 71

~

I .;;

!.1,:;~
I

Jt

!.I --

-HJ
I
I

R494
27

10
I

r~

6

-

-3
~1

I
I

_5

, 'cR387

-

R3l9
20

l

R3l8
100

__J

SCA
GENERATOR
NO. I

~.____o-- ---11--<'.2->-4 - - 4 - - - 4 - - 1 - - 1 --i--1 _
4

! ~

•:.-<>- --+-o-5-+--1---

1

!+.-.-ll.....---+--<:">-'- -

1

-,- ,:;

Z 301
---L.:.:
___
.....J

r

I

P L ATE
ON-OFF

I HJ

'--'->---+-0' +-----....J
r-

I
I

I
I
I

PLATE ON (NO.)

r--C.-C-C......C--'---

*

I LoCALI, rlREMOTEI

- E3I0

5\
~

;

10

I

_noI

I/

.....
.......... ' -

!

8

6--

18304

I

I

,---o-il
14 I
o-, I 12

2

a

I

-I

R311
IMEGO

R310 ~
I MEG010

P.A.
PLATE
M30
VOLT A G E ~

,~ c31:

1

T

I
L-__

_

11

J-!,._---1'111--..

e,~ R30 I

IOO

_6

I
2

1

5 AMP '

~ ':;

111

~

-

>--

1
,

I, 10

9

'

8

__J

RESET

r

°11.__
3

~ •1

I

~I

'2J i

I

s•

----<~,..

3 11

•
S312

!PLATE!

tL
3 -3 - -- 4

~
s l 14

S3 l3

-

N

t- Q

-

'Z

~ ::::, r



i5J
0
4'1'.'.:

c:x

O

~r.:,

..J ~ ~

:E

I

>:

2

1

ITB30I

I

~

POWER IN,,200 TO
250 V AC ·soCPS

4

-=-

R:3 25
100

-+--+1-+--~--o-.~•:

6

-=

"// ✓ /

- -

1

I

___ _

_

l
.I · I
t= ·1""

_J

C205
.02UF

lh

c206 1
IQOQ I

R305
3 IK

A

2

1

I

P.A.

PLATE
CURRENT
M303

"=

7 T 30 3

~

I

6-

ill

--=---4+-l-t-'----l-----::5.---+-- - - 3
3 1,_

10

2

I

CR30 I

-

_,_
-=K 05
OVEI LOAD

R304
50
2

R306
10
V30I
0D3

_.._
•

R303
10

,1

~

l

c 30 4

2000

1

200 0

1

.I

-4.7

.I
.I
.I

V302
003

•

0

_....

R309

5K

I)

2

~

-- - 7
PO WER
AMPLIFI ER
COMPARTM E NT

NOTES :
I. SUPPL IED WITH RE MOTE CONTROL ON LY. R494 MAY CH ANGE PER CUSTOM ER REQUI REMENTS

1

L20I

J:d'~ *
~:\

I

c~~7
1000

L

I

-

FS
!MU LTIMETER( .
M30 I

\
,
\

'7 1

s : N _I_

rF SSCREEN
400V DC 1\

I/
I\
C202
.02U F

-., .

--

R20I
2700

C204
.ofyF

--f

, , ;::12

f

.I
.I

I

.I
.I

II 1

J304

,______ _ _ __ __ _ _----4'-.:>,--< MONITOR

OUTPUT

~~

L-!
) "~,"__,,.,,L,.,,20,.,,3'"""'-r>T-J2-<_~r>24

I

c 2os
OUTP UT

COuPU,O

I

c~o II

, -

P ~ i ,.cF-'w'"'o'--_ _ _o_
c_30
_1
_ __ __

).r304

I

)301A

:.;.4=-,

~ 305 3 E313

I I LlOS "~
,~--Ll~:~~

E3 I 3

I

A-=j30\ RF ouTPu T

T

T

,s:i:, "~

I

REMOTE

I

-I

I-

FORWARD!

\

1 ,

II

I

-x-

C309
25
C30 8

C306
25
C305

25

25

HARMONI C F ILTER
(SEE NOTE 5l_ _

I II

~

\

\

----- ----------"

I

-:r

J

I

I
REFLECT ED

I
+------1(1--- I
-_ __ _J
C203
02UF

I

.I

4c:~?6e

,~---K-----

\JI'
C213
4 - SO
I GRID
T UN I NG I

•,

.I

I/

- '-C2I6
r r-- I000

-f

c~

.I

4.5 -9-5

2 •4 • C20 I
6 , 8 .02UF

R202
3300

T-:-

I/
II
I.I

'"' 1
,HJ09

,_;.
I/
_._

2. SCA GENERATORS OPTIONAL FOR STEREO OR MULT IPL EX
3. AL L GROU NDS UNLESS OTH ERWISE SPECIF I ED ARE CONNECTED TO BASE
PLAT E OF CAB I NET CHASS IS
•
4 . JUMPER WHEN USED AS 250 WATT TRANSMI TTER.
5. HARMON IC FILTER NOT PART OF 8830- 1, USED ONLY WHEN B830 - I IS CONN ECTED
TO ANTENN A . WHEN NOT USED, CONNECT J 202 TO DC301-1 .
6 . UNLESS OTHERWISE INDICATED '
ALL RESISTANCE VALUES ARE IN OHMS
ALL CAPACITANCE VALUES ARE IN MICROMICROFARADS
ALL INDUCTANCE VALUES ARE IN MICROHENRYS
7 , LATCHI NG RELAY ( Z30 3) SUPPLIED WI TH REMOTE STEREO ONLY
8 . FOR REMOTE CONTROL REMOVE JUMPER BETWEEN TERMINALS 9 AND 10 OF TB302
9 . R3l8 AND R3l9 RESISTOR VALUES MAY CH ANGE PER CUSTOME R REQUI REMENTS.

r / .1.1.1
I,,
I,,

,

,.

PA
SHORTING
SWITCH

R203
47

1

S307

I.I
/
/
/
/

P LAT E,!
TUN I NG

I
R322
1110
4 02_1<
~ ~
E:3040---'V\/v- +-''O..--u._,.//r ;,_
L___ _,,_..,...4:.c,-.,
\
~9 - E 3 I 7

5

- - C30 3

I

R308
5K

2

R320
390

3
I

L2 0 2

I

C2I4
10 00

5

, ... 2

4

S20I

_!00~

E303

3~
2

"\I
/I
C3 0 2
4UF

-

_8

~

C2I I

R3 I 6

S.3$; j::;:
9

~

,J !

I

2

3t:
I_

C2IB
1000

.J- Tl
I
4~-"Nl,--------=-o-----~,K-~J: -C-.__- ::~~~~~~~~~:-~~~~~~~:~..!.J
"--~

L302
10

I/
I/
II
II
II
II

.I

I
I

2560

Q---Vl/l,.--11--- - - . . - -- - -

= L30 I

~

Ir

r-:
R323
I I 2

I
I

10

~

I
it
I

R:307

E30 1

~

.I

7
CR302

~

, vC2 l 7
- - 1000

c 2 I2

-:-

V20I

__J_

~

I

[/

~

REAR DOOR
SHORT I NG SWI TCHES

3

:---"'+1----+-----+-----l- - - - ~5 J • 6

E3I2 T

C2l0 ,i.,
1000--

T P302~--- - - - - '
~~

5

PL~~I A~ON T

~

"='

5

I

2

-- - - --

Z20 I

T302
,)

-

..

5~

... ...

TP30l > - I

_ __ ---

1
1

2

,)

)
7 E3I4

_E322

RE AY
l
3

~~

K:,02

-r~-;---l-+-+-½-Hf-+ - - - -- -+ - - + - - - - -- - - -- - -- -- -- - - ----...;_&-1oi
-_s 11 3..,__L
Ii
~
E3l?J:"_ '
E308 ~

z
\'o

K304
PLATE
CONTACTOR
I
2

,l_

'l I I

~:

L__

C8301 I
12 AMP
REAR DOOR INTERLOCKS
2 l.r,. 2
I .r-,.2 1~

'v'-r''-r'~~

i

l

( SEE
G_o:!:£

_ _ _ _ _ _ _ _ _ _ _ _r;----,--A--,1_
j.;.
1
1 7
2

I

'------- -~

-7

REMOTE

I

6t 66

PART OF
TB303

18306

~

I
.....0-.....

__

'J'~~

5 AMP
• _

II

i

~

-

OK

1k:-/ 5L- L

- - --

r
I

DS302
RED

IK

_ _ __

.,_----4t--- --------+-----+- -,_,..,_.

::2

F302

2

3

R:;~y

~

I
I
I

R3 3 ; ~ THERMAL
680
RELAY
2
3 K307 AUX

I

I

'i

I
2

-i-

F30I

7j I

--7- --

R302
II<

1 1

220K 2·•_2,

2

y ASSEM BLY

.

11

'

S3 I 4

L---.

--r- :-~g-- T7
l

R:313 IRM3EIG20
IOK

5

'

II

K~OI
F IL CO~T RELAY

1

!

PA
BLOWER

830 I
E3l7

7
I
3I

BLOWERINTERLOCi'

I

---C~~ ~

, TS308-4 - - - -

'.

-

r

~ - - - l - -~1 -

-

I

CABI NET
FAN
8302

T 8309

'
•a-+--+---+------+------+--4---4---1-----'D-''I
-

T

4

o

1""-<6>---E-30-0-7_ -+---o-l--- ~

~

DS30I r,;:::::::i I
GREEN~ 2

:

II II II II
11
1

°"[9

LI NE
VOLTAGE

~~A~ ~ ~

--i--

E3I2
J305 P309

1

F303
4AMP

~220K
E3I0

-~

IIII

7
-t--<>--t-- - - - -- - - - - - -- --+- - -- - --

-

7

.-~--=;-;::,------------+-+---+----+-------+--l------+--4---~,

i

TB305 ! 0 0 0
I
I I
' IL.-'-12=-c1.:..1.:.::10:._::9~8_;....7_6::,_.:5:___;4c..,.=2____:,I___::c3__J
PLATE ON ( NO.)

4

I

9
---C8>"-----ll-+j-ll--l---+--4-1-+---4-..,..._.,

,

5

!•,--c-: >---+-O,-+-----------'

?

TB3I3

~~ 9
1011'1-<>-----W'.::2

IIII

12

\

7
I

I

3 •)4 4

Ef---+.f·
-=

+ }REMOTE

- - C3I7
'r"' OOIUF

7
'--O--- -------......~

21' ]

!.!__ I

PLATE OFF (NC)
....:..::..:::.:.=c.=.:......!.:.:=_+O--f~
- - -- - ----+------+--- -----11_.:..11....:-11-4-U-l-4-n....:.-=--t_J

I

5

8

2

u.

5

..J

I I I

1
- {

~

-

f!.

n_

13 II

I I I

,

jFIL~~:NTj

s 302

g_

OFF (NCI

w
~
c:! . ~
_J

0

w

"'0::

l ::

~ , 4

Sill

I

06
PLATE

'(10(~11 ' I

:::i;?
...- ...:,

0

w,-

. .J ..Jg

I, I I I

-

!FILAMENT ON!

~9

I

z

E3I0

'---++-+--~~:...;.;...:...;.;...~::..:..:..._+-<>-+- - - -- - - --+rt--'-Q9
GROUND

o

r-.~t-----+------+-t,-H
, ,++-i-+--+-H+-++++-,+------ - --=-~_-.......- - -- - ---1---W~-oJI

_10

~

rs3w
,.....:...;....

1

PART OF
TB302

II II

..J...

FILAMEN T ON ( NO l

... ...u.
:c

- ,

2

o

1-

::.

:

II II
I I I_[)I

PART OF
18302

,:;3

3'

4l ,

I I I I

ADJUST

1

Fl LAME NT OFF I NC l

I

I

-= I, I I I
11 I I I

7

I

2

<>

L _ _ _ _ l111

I
I

____s_,,_2 _

I

y

LL

2
R424
220

>-06

1

R3I7
75

REMOTE FAIL SAFE ' (SEE NOT E Bl
'-,-_

8

I

SCA
_
GENERATOR [
NO. 2

I
I

6

8

L&..

3
z

~

100

CR389

0

wo-

...J ,r,

R423

..-,

~

-

'-'
<(
>

E316¾

ft~ -il-4i
r

I
I
I
I
I

i ~ ~

6

I

Iri~~~l

STEREO
REMOTE
CONTROL

F ILAMENT TB~
ON-OFF

I I

f

E3I3

I;

s:

I I
7
1I
L _ __i_J
-1, Lf-""TTJ
-= I I (SEE 2~0TE J
I I
._ ____ 7 11
JI

(SEE
NOTE 9)

I
I

TB307

Dr - -_!_~(!)

I I

_.__~==--__, __

~

R42I
IBOO

R422
4700

L" __"'= --=

B

IL.:no3
- ...J
______

r
I

"°re32_3__

- - C3l5
T .OIUF

7

B303

L

24

~ ~

WW

1-

,.
<(

LLl..i..u

SEE
~ o.. "- SEE "- u.
NOTE 4r1 r 1 NorE 4 r 1

::E

I

I

~IS:315
,~~
? I

TB336 1
~9

H

:

O

e

z z

t!>.-55

tz~··

~

~-7

~

0~
Q:w

z

I

r

I

•

~~

"

goo

,----A----..

iE317

I
I

jl

)

TO REMOTE
CONT ROU

a:: w
~~
0 <(
...J a:: z
a::
a:: 0
ww :!:

~ ~ ~

8 9 10 I

-STERE0--7

•

PART OF

T O HIGHER
POWER PA

WATTMETER!
S308

PART OF
TB333

a::

~ ,--- - - - - .
R. F.
._ WATTMETER

:?
ii!

3

i.::-.,,:;.;::,.._

_

__:...;> R32I

IOK
2

C2151\

-- ~

o_ _

4 0MAI

,

P30 1
GR I D , EXCITATION
l FS 40MAI
' INPUT

,
t

\ ____ ____ ~

S307

• I Ol

!7l 6

AUDIO INPUT

STEAM POWERED RADIO.COM

Figure 5- 1.

Overall Schematic, B830- 1 250- Watt FM Power Amplifier
5- 3/ 5- 4



File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.5
Linearized                      : Yes
Author                          : Collins Radio Company
Create Date                     : 2018:05:25 16:29:58-07:00
Keywords                        : Collins 830B-1A 250 Watt FM Broadcast Transmitter Manual, Collins 830B-1A, 830B-1A FM Transmitter, 830B, 830B FM Transmitter
Modify Date                     : 2018:05:26 13:37:38-07:00
Has XFA                         : No
XMP Toolkit                     : Adobe XMP Core 5.6-c015 84.159810, 2016/09/10-02:41:30
Producer                        : Adobe Acrobat Pro DC 18 Paper Capture Plug-in
Metadata Date                   : 2018:05:26 13:37:38-07:00
Format                          : application/pdf
Title                           : Collins 830B-1A 250 Watt FM Broadcast Transmitter Manual
Description                     : Collins 830B-1A 250 Watt FM Broadcast Transmitter Manual
Creator                         : Collins Radio Company
Subject                         : Collins 830B-1A 250 Watt FM Broadcast Transmitter Manual, Collins 830B-1A, 830B-1A FM Transmitter, 830B, 830B FM Transmitter
Document ID                     : uuid:b37ee27e-3f71-4ed0-b9f9-81603be77a36
Instance ID                     : uuid:21fc76a1-9f6a-4dc8-81ae-e06207042f6d
Page Count                      : 127