null  null
TM 11-5820-498-35
DEPARTMENT OF THE ARMY TECHNICAL MANUAL
DS,GS, AND DEPOT
MAINTENANCE MANUAL
RADIO SETS
AN/VRC-53, AN/VRC-64, AN/GRC-125
AND AN/GRC-160
AND
AMPLIFIER-POWER SUPPLY GROUPS
OA-3633/GRC AND OA-3633A/GRC
This copy is a reprint which includes current
pages from Changes 1 through 4.
HEADQUARTERS, DEPARTMENT OF THE ARMY
DECEMBER 1969
TM 11-5820-498-35
C4
HEADQUARTERS
DEPARTMENT OF THE ARMY
WASHINGTON, DC, 12 October 1981
Change
No. 4
Direct Support, General Support, and
Depot Maintenance Manual
RADIO SETS AN/VRC-53 (NSN 5820-00-223-7467),
AN/VRC-64 (NSN 5820-00-223-7475),
AN/GRC-125 (NSN 5820-00-223-7411) AND
AN/GRC-160 (NSN 5820-00-223-7473) AND
AMPLIFIER-POWER SUPPLY GROUPS
OA-3633/GRC AND OA-3633A/GRC
(NSN 5820-00-973-3383)
TM 11-5820-498-35, 22 December 1969, is changed as follows:
1. New or changed material is indicated by a bar in the margin.
2. Remove and insert pages as indicated below.
Remove
Insert
None. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A/(B blsnk)
1-1 and 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 and 1-2
4-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..4-1
A-1 and A-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1 through A-2
3. File this change sheet in front of the manual for reference purposes.
DISTRIBUTION:
To be distributed in accordance with DA Form 12-51, Direct and General Support Maintenance requirements
for AN/VRC-53, 64, AN/GRC-125, 160.
TM 11-5820-498-35
C3
HEADQUARTERS
DEPARTMENT OF THE ARMY
WASHINGTON, DC, 28 April 1981
CHANGE
No. 3
Direct Support, General Support, And
Depot Maintenance Manual
RADIO SETS AN/VRC-53 (NSN 5820-00-223-7467),
AN/VRC-64 (NSN 5820-00-223-7475),
AN/GRC-125 (NSN 5820-00-223-7411), AND
AN/GRC-160 (NSN 5820-00-223-7473), AND
AMPLIFIER-POWER SUPPLY GROUPS
OA-3633/GRC AND OA-3633A/GRC
(NSN 5820-00-973-3383)
TM 11-5820-498-35, 22 December 1969, is changed as follows:
1. Title of the manual is changed as indicated above.
2. This change covers OA-363A/GRC, procured on Contract DAAB07-79-C-0068 (para 1-4a(1)).
3. New or changed material is indicated by a bar in the margin.
4. Remove and insert pages as indicated below:
Insert pages
Remove po.ges
1-1 and 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 and 1-2
3-17 and 3-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17 through 3-18.1
Figure 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 4-9
5. File this change sheet in the front of the manual for reference purposes.
By Order of the Secretary of the Army:
Official:
E. C. MEYER
General, United States Army
Chief of Staff
J. C. PENNINGTON
Major General, United States Army
The Adjutant General
DISTRIBUTION:
To be distributed in accordance with DA Form 12-51 Direct and General Support maintenance
requirements for AN/VRC-53, AN/VRC-64, AN/GRG-125, AN/GRC-160.
WARNING
Remove the battery from the radio sets when the radio sets are not being used. This iS
required to prevent Hydrogen gas (a by-product of Magnesium Battery, BA-4386/U
discharge action) from accumulating. Personnel may be injured and equipment damaged
if the gas explodes.
You can tell the difference between Magnesium Battery, BA-4386/U, and Lithium
Battery, BA-5598/U, by looking at their size. The lithium battery is half the size of
(smaller than) the magnesium battery. Both the magnesium and lithium batteries are
disposed of in a sanitary landfill.
WARNING
A lithium battery is used in this equipment, and is potentially hazardous if misused
or tampered with before, during, and after discharge. The following precautions
must be strictly observed to prevent possible injury to personnel or damage to
equipment.
DO NOT heat, incinerate, crush, puncture, disassemble, or otherwise mutilate the
batteries.
DO NOT short circuit.
DO NOT recharge.
DO NOT bypass internal fuse or replace with a fuse of a different rating. Replacement fuses are packed two per every ten batteries.
DO NOT store in equipment during long periods of unuse in excess of 30 days.
TURN OFF the equipment immediately if you detect the battery compartment
becoming unduly hot or rapidly increasing in temperature, hear battery venting
(hissing sound), or smell irritating sulfur dioxide gas. Remove and dispose of the
battery only after it is cool (30-60 minutes).
DO NOT use carbon dioxide extinguishers on exposed lithium fuel fires. Flood the
burning material with water or use graphite type compounds or extinguishers to
extinguish burning lithium.
Change 4
A/(B blank)
* TM 11-5820-498-35
HEADQUARTERS
DEPARTMENT OF THE ARMY
W ASHINGTON , D. C., 22 December 1969
T ECHNICAL M ANUAL
o. 11-5820-498-35)
DS, GS, and Depot Maintenance Manual
RADIO
SETS
AN/VRC-53,
AN/VRC-64,
AN/GRC-125
AND AN/GRC-160, AND AMPLIFIER-POWER SUPPLY GROUPS
OA-3633/GRC AND OA-3633A/GRC
Parapgraphs
CHAPTER 1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1—1-4
2. CIRCUIT FUNCTIONING
Section I. Radio, and radio with intercom, circuit functioning . . . . . . . . . . . . . . . . . . . . 2-1—2-5
II. Retransmission circuit functioning . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6—2-8
III. Amplifier-Power Supply Group OA-3633(*)/GRC, circuit functioning . . . . . . . . . .2-9—2-11
CHAPTER 3. DS AND GS MAINTENANCE, AMPLIFIER-POWER SUPPLY GROUP
OA-3633(*)/GRC.
Section I. General troubleshooting techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1—3-4
II. OA-3633(*)/GRC; troubleshooting procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5—3-11
III. OA-3633(*)/GRC, parts removal and replacement procedures . . . . . . . . . . . . . . . . . .3-12—3-16
IV. OA-3633(*)GRC, testing procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17—3-24
CHAPTER 4. DEPOT OVERHAUL STANDARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1—4-4
APPENDIX A. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
*This
manual
supersedes
TM
11-5820-498-35,
7
February
1963,
including
all
Page
1-1
2-1
2-8
2-11
3-2
3-5
3-13
3-18
4-1
A-1
changes.
i
TM 11--5820-498-35
CHAPTER 1
INTRODUCTION
1-1. Scope
This manual covers direct support (DS), general support (GS), and depot maintenance of Amplifier-Power
Supply Group OA-3633(*)/GRC, including detailed circuit functioning, troubleshooting, testing, and repair
procedures. This manual also covers circuit functioning
of Radio Sets AN/VRC-53, AN/VRC-64, AN/GRC125, and AN/GRC-160.
NOTE
(OA-3633(*)/GRC represents OA3633/GRC and OA-3633A/GRC (para
14).
Item
AN/VRC-53, AN/VRC-64, AN/GRC-125, and
AN/GRC-160.
a. Operation of the radio sets (which include the
OA-3633(*)/GRC), with and without crew-member
control boxes in the radio-intercom system, and the
operator’s and organizational maintenance of the radio
sets is covered in TM 11-5820-498- 12.
b. Following is a list of publications covering circuit
functioning, maintenance, and repair parts for various
components of the radio sets covered in this manual.
Technical manual
Coverage
TM 11-5820-498-12. . . . . . . . . . . . . . . . . . . Operation and organizational maintenance.
TM 11-5820-498-35 . . . . . . . . . . . . . . . . . . . DS/GS maintenance
RT-505/PRC-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5820-398-12 . . . . . . . . . . . . . . . . . . . Operation and organizational maintenance repair
parts.
TM 11-5820-398-35 . . . . . . . . . . . . . . . . . . . Circuit functioning and DS, GS, and depot
maintenance.
TM 11-5820-497-34P. . . . . . . . . . . . . . . . . . DS, GS, and depot maintenance repair parts.
TM 11-6625-514-12 . . . . . . . . . . . . . . . . . . . DS maintenance using Test Set, Electronic Circuit,
Plug-In Unit AN/GRM-56, -55A, -55B, or -55C to
locate faulty modules.
RT-841/PRC-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5820-667 -12. . . . . . .
Organizational maintenance repair parts.
TM 11-5820-667-35. . . . . . . . . . . . . . . . . . . Circuit functioning and DS, GS, and depot maintenance, including troubleshooting for defective
modules.
TM 11-5820-667-34P. . . . . . . . . . . . . . . . . . DS, GS, and depot maintenance repair parts.
OA-3633(*)/GRC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5820-498-12 . . . . . . . . . . . . . . . . . . . Organizational maintenance.
TM 11-5820-498-20P. . . . . . . . . . . . . . . . . .Organizational, maintenance repair parts.
Operator, organizational, DS, GS, and depot maim
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5820-401-12 and
tenance, and repair parts.
TM 11-5820-401-35-9
AT-912/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5820-401-12 . . . . . . . . . . . . . . . . . . . Operator, organizational, DS, GS, and depot maintenance, and repair parts.
AS-1729/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5985-262-15 . . . . . . . . . . . . . . . . . . . Operator, organizational, DS, GS, and depot*
tenance, circuit functioning, and repair parts.
H-138/U and H-138A/U . . . . . . . . . . . . . . . . . . . . . . . TM 11-5965-257-15 . . . . . . . . . . . . . . . . All maintenance levels and repair parts.
H-189/GR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5965-280-15 . . . . . . . . . . . . . . . . . . . All maintenance levels and repair parts.
c. Following are publications covering various audio
ment used with the radio sets covered in this manual.
accessories and crewmember radio-intercom equipCoverage
Publication
Item
Headset-Microphone H-161/U and H-161/U. . . . . . TM 11-5965-262-13 . . . . . . . . . . . . . . . . . . . All maintenance and repair parts.
Headset Microphone Kit . . . . . . . . . . . . . . . . . . . . . . TM 11-5965-282-15. . . . . . . . . . . . . . . . . . . All maintenance and repair parts.
MK-1039/G (also used in CVC Helmet).
Intercom equipment:. . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5830-340-12
TM 11-5820-401-30-4,
Amplifier, Audio Frequency
TM 11-5820-401-35-6, -7, and -8
AM-1780/VRC, and Controls,
Intercommunication Set
C-2296/VRC, C-2297/VRC, and C-2298/VRC.
Interunit cabling, mounting. . . . . . . . . . . . . . . . . . . SB 11-131 . . . . . . . . . . . . . . . . . . . . . . . . . . . Items comprising installation kit, including Federal
stock numbers for kit parts.
hardware, audio accessories, etc.; provided in
installation kits as required for particular vehicle
installation.
Instructions for installing particular radio
TM 11-2300 series; refer to DA Pam
Head, Mic Kit MK-1697/G (in new CVC
and radio-Intercom configuration.
310-4. TM 11-5965-286-14
Helmet).
Change 4
1-1
TM 11-5820-498-35
d. For applicable forms and records, refer to TM
11-5820-498-12.
e. For OA-3633(*)/GRC and AM-2060(*)/GRC differences, and for differences in equipment and radio configurations, refer to paragraph 1-4. (AM-2060(*)/GRC
represents AM-2060/GRC and AM-2060A/GRC.)
1-2. Index of Publications
DA Pam 310-4. Refer to latest issue of DA
Pam 310-4 to determine whether there are new
editions, changes, additional publications or
modification work orders pertaining to the
equipment.
1-3. Maintenance Forms, Records and
Reports
a. Reports of Maintenance and Unsatisfactory
Equipment. Department of the Army forms and procedures used for equipment maintenance will be those
prescribed by TM 38-750, The Army Maintenance
Management System (Army). Air Force personnel will
use AFM 66-1 for maintenance reporting and
TO-00-35D54 for unsatisfactory equipment reporting.
b. Report of Packaging and Handling Deficiencies.
Fill out and forward SF-364 (Report of Discrepancy
(ROD)) as prescribed in AR 735-11-2/DLAR
4140.55/NAVMATINST 4355.73/AFR 400-54/MCO
4430.3E.
c. Discrepancy in Shipment Report (DISREP) (SF
361). Fill out and forward Discrepancy in Shipment
Report (DISREP) (SF-361) as prescribed in AR
55-38/NAVSUPINST4610.33B/AFR75-18-/
MCOP4610.19C/DLAR 4500.15.
1-3.1. Reporting Errors and Recommending Improvements
You can help improve this manual. If you find any
mistakes or if you know of a way to improve the
procedures, please let us know. Mail your letter, or DA
Form 2028 (Recommended Changes to Publications
and Blank Forms) direct to: Commander, US Army
Communications-Electronics Command, ATTN:
DRSEL-ME-MQ, Fort Monmouth, NJ 07703. In either
case, a reply will be furnished direct to you.
1-3.2. Reporting Equipment Improvement
Recommendations (EIR)
If your equipment needs improvement, let us know.
Send us an EIR. You, the user, are the only one who can
tell us what you don’t like about your equipment. Let
us know why you don’t like the design. Tell us why a
procedure is hard to perform. Put it on an SF-368
(Quality Deficiency Report). Mail it to Commander, US
Army Communications-Electronics Command, ATTN:
DRSEL-ME-MQ, Fort Monmouth, NJ 07703. We’ll
send a reply.
1-2 Change 4
1-3.3. Destruction of Army Electronics
Materiel
Destruction of Army electronics materiel to prevent
enemy use shall be in accordance with TM 750 -244-2.
1-3.4. Administrative Storage
Administrative storage of equipment issued to and
used by Army activities will have preventive maintenance performed in accordance with the PMCS
charts before storing. When removing the equipment
from administrative storage, the PMCS should be performed to assure operational readiness. Disassembly
and repacking of equipment for shipment or limited
storage are covered in paragraph 1-3.3, TM
11-5820-498-12.
1-4. Differences in Equipment and
Configurations
a. The OA-3633/GRC includes Cable Assembly, Special Purpose, Electrical CX-4655/GRC (7 or 11 inches
long) (fig. 3-5) and Amplifier-Power Supply
AM-2060/GRC. The OA-3633A/GRC includes the
CX-4655/GRC and AM-2060A/GRC.
(1) The AM-2060A/GRC is the same as the
AM-2060/GRC except that the A model has added two
filter capacitors C8 and C9 to the 25-5-volt dc input at
connector J3 (fig. 4-9) and the use of a rubber boot for
the front panel SPKR switch (fig. 3-16). However, on
equipment identified under Contract No. DAAB
07-79-C-0068, capacitor C8 was eliminated and diode
CR1, 1N4720 was placed in parallel with C9 (see note
12 in figure 4-9).
(2) Throughout this manual, AM-2060(*)/GRC applies to AM-2060/GRC and AM-2060A/GRC unless a
particular model is specified.
b. The OA-3633/GRC is used with the
RT-505/PRC-25 (TM 11-5820-398-35) in the
AN/VRC-53 and AN/GRC-125 radio configurations;
and with the RT-841/PRC-77 (TM 11-5820-667-35) in the
AN/VRC-64 and AN/GRC-160 radio configurations.
All references to a receiver-transmitter in this manual
apply to the RT-505/PRC-25 and RT-841/PRC-77 unless
one is specifically mentioned.
c. The OA-3633(*)/GRC can be used with Antenna
Matching Unit MX-2799/VRC (part of Antenna
AT-912/VRC (TM 11-5820-401-35) which is used in the
AN/VRC-53 and AN/GRC-125 configurations),
AT-912/VRC-53 and AN/GRC-125 configurations), and
with Matching Unit-Base MX-6707/VRC ((TM
11-5985-262-15) which is used in the AN/VRC-64 and
AN/GRC-160 configurations). All references in this
manual to antenna matching unit apply to the
MX-2799/VRC and MX-6707/VRC, unless one is specifically mentioned.
TM 11-5820-498-35
CHAPTER 2
CIRCUIT FUNCTIONING
Section I. RADIO, AND RADIO WITH INTERCOM,
CIRCUIT FUNCTIONING
2-1. General
a. The radio sets include a receiver-transmitter
(RT-505/PRC-25 or RT-841/PRC-77), a whip
antenna (AT-912/VRC or AS-1729/VRC), the
MT-1029/VRC, and OA-3633(*)/GRC. An audio
accessory, interconnecting cables, and mounting
hardware to mount the radio sets in a vehicle are
provided in the installation unit (kit) applicable
to the radio set installation (SB 11-131).
b. The OA-3633(*)/GRC converts the nominal
24-volt vehicular battery to operating voltages
(13, 2.6, and 3 volts dc) for itself and the receiver-transmitter. It also has provision for listening on a loudspeaker to the signals received on
the receiver-transmitter, and for matching the
output of the receiver-transmitter to the whip antenna matching network.
c. The radio sets are also capable of operating
with a vehicular radio-intercommunication (intercom system. The intercom system includes a central audio and power control (Amplifier, Audio
Frequency AM-1780/VRC), and crewmember
control boxes (Controls, Intercommunication Set
C-2296/VRC (located on the rear outside the vehicle), C-2297/VRC (for vehicle driver), and
C-2298/VRC (for other crewmembers)). The radio-intercome boxes, interconnecting cables,
mounting hardware, and audio accessories required for the radio set with an intercom system
are provided in the installation kit applicable to
the vehicle in which the equipment is used (SB
11-131). The crewmembers can talk either on the
intercom system or over the receiver-transmitter
in the radio set.
d. The internal circuit functioning of the reand
ceiver-transmitters,
whip
antennas,
RT-1029/VRC as well as the intercom system
control boxes is provided in the manual associated with the particular equipment. Refer to
paragraph 1-1b and c for the associated publications.
e. The module circuits in the RT-505/PRC-25
are functionally the same as those in the
RT-841/PRC-77. Those that are identical in both
receiver-transmitters have the same reference
designation (for example: dc to dc converter A10
and speech amplifier limiter A22). Those modules
that are functionally identical but have internal
circuit differences are identified with different
reference designations. For example: squelch
relay control A24 and receiver audio amplifier
A25 in the RT-505/PRC-25 are the same, as
squelch relay control A54 and receiver audio amplifier A55 in the RT-841/PRC-77. In this manual those functionally similar modules are identified thusly: A24/A54, A25/A55, A22/A22, etc.
2-2.
Radio and OA-3633(*)/GRC, Circuit
Functioning Without Crewmember Control Boxes
(fig. 4-3)
When the radio configuration does not include
crewmember control boxes, the radio and
OA-3633/(*)GRC circuit functioning are given in
a through d below. Figure 4-3 shows the circuits
in radio standby mode; that is, neither transmitting or receiving a radio signal.
a. Circuit Setup. For this radio configuration,
the following conditions are required:
(1) The link in the MT-1029/VRC must be
set for local control of the dc power to the equipment.
(2) On the AM-2060(*)/GRC, the POWER
circuit breaker switch is set to ON, and the ANT.
FREQ. CONTROL switch is set to a position that
includes the frequency at which the receivertransmitter is tuned. The SPKR switch is set to
ON.
(3) On the receiver-transmitter, the function switch S1 is set to ON, and the frequency
selector switches MC and KC (not shown in fig.
4-3) are set to the desired operating frequency.
An audio accessory (such as the H-189/GR,
H-161/U, or equal) is connected to one of the receiver-transmitter AUDIO receptacles FL1 or
FL2.
2-1
TM 11-5820-498-35
b. Power Distribution.
(1) Power from the battery source is applied through the MT–1029/VRC and the
AM–2060(*)/GRC PWR switch CB1 to audio amplifiers Q1 and Q2, and to regulator amplifiers Q3
and Q4. The dc power is also applied through
ANT. FREQ. CONTROL switch S2 to the control
circuits of the antenna matching unit
(MX-2799/VRC or MX-6707/VRC).
(2) From the AM-2060(*)/GRC, the dc operating voltages are applied to the receiver-transmitter: 13 volts for both receiver-transmitters
(RT-505/PRC-25 and RT-841/PRC-77), and 3
and 2.6 volts for the RT-505/PRC-25 only.
c. Radio Transmission. When the push-to-talk
switch in the audio accessory is operated to radio
position, the following circuit operations occur.
(1) The audio accessory push-to-talk switch
provides a ground through receiver-transmitter
relays K1 and K2 for the 13 volts supplied by Q3
and Q4 in the AM-2060(*)/GRC.
(2) In the AM-2060(*)/GRC, K1 also operates and disconnects the loudspeaker from the
audio circuit.
(3) In the receiver-transmitter, the following actions occur:
(a) Relay K3 remains unoperated. Relays
K1 and K2 operate to apply power to the transmitter circuits of the receiver-transmitter. In the
RT-505/PRC-25, K2 applies power to the filament of the power amplifier V1.
NOTE
Relay K1 in the AM-2060(*)/GRC also operates and disconnects the loudspeaker from
the output of Q1 and Q2. This operation
prevents sound feedback between the loudspeaker and the audio accessory microphone.
(b) Speech signals from the audio accessory now applied through speech amplifier A22,
transmitting amplifier, and the power amplifier
(P.A.) stages to the antenna for transmission to
the distant radio station.
(c) Sidetone of the speech amplifier is applied from speech amplifier A22 through receiver
audio amplifier A25/A55 to the audio accessory
earphones.
d. Radio Reception. For radio reception, the
push-to-talk switch of the audio accessory is unoperated. The following circuit operations occur
when a signal is received from the distant radio
station. Receiver-transmitter relays K1, K2, and
K3, and the AM–2060(*)/GRC relay K1 is unoperated.
2-2
(1) Receiver-transmitter function switch set
to ON.
(a) A signal received
applied through the RF-IF amplifiers and discriminator circuits to receiver audio amplifier
A25/A55.
(b) From the A25/A55, the speech signal
are applied as follows:
1. To the audio accessory earphone.
2. Through AM-2060(*)/GRC audio
amplifiers Q1 and Q2 to the loudspeaker.
(2) Receiver-transmitter function switch set
to SQUELCH. When the function switch is set to
SQUELCH, signals received at the antenna must
contain a 150-Hz squelch tone. Until the 150-Hz
tone is received, receiver-transmitter relay K3 is
unoperated. Relay K3 provides a short circuit to
ground through K3 contacts and function switch
S1 for the output transformer in A25/A55. Thus,
the FM rushing noise is not heard in the audio
accessory earphones or the loudspeaker.
(a) Signals received at the antenna are
applied through the RF-IF amplifiers and the
discriminator circuits to receiver audio amplifier
A25/A55.
(b) From the discriminator, the 150-H
squelch signal is applied to squelch relay contr
A24/A54.
(c) A24/A54 then provides a closed circuit to operate relay K3. When K3 operates, it removes the short from the output transformer in
A25/A55.
(d) Speech signals are now applied from
the output transformer in A25/A55 to the audio
accessory earphones. The speech signal is also applied through the AM–2060(*)/GRC audio amplifier Q1 and Q2 to the loudspeaker.
2-3.
System Power Distribution, Including
Crew-member Control Boxes
(fig. 4-4)
The distribution of power to operate the radio,
AM–2060(*)/GRC, and the crewmember control
boxes is controlled from the AM–1780/VRC.
Whenever the intercom equipment is connected to
the radio and the intercom system, the link in the
MT–1029/GRC must be connected for remo
power control operation as shown in figure 4-4.
The setting of the AM-1780/VRC MAIN PWR
switch determines the path of the power distribution from the MT-1029/VRC. The charts in a and
b below trace the distribution of power through-
TM 11--5820-498-35
out the radio and crewmember control boxes in
system.
a. AM–1780/VRC MAIN PWR Switch at
NORM Position.
From
To
J21, pin B . . . . . . . . . . . . . . . . . . . . . . .
Pin B . . . . . . . . . . . . . . . . . . . . . . . . . . .
J501, pin B . . . . . . . . . . . . . . . . . . . . . .
Switch S504, rear . . . . . . . . . . . . . . . .
Pin D . . . . . . . . . . . . . . . . . . . . . . . . . . .
J22, pin D . . . . . . . . . . . . . . . . . . . .
J3, pins J and Ca. . . . . . . . . . . . . . . . .
Switch S2 . . . . . . . . . . . . . . . . . . . . . . .
J22, pin B
Pin B
Switch S504, rear (NORM position)
J501, pin D
Pin D
J24, pin J
Switch S2, front and rear
J4 (pins used depend on setting of
S2)
Q1, Q2, Q3, and Q4, and R17
J2, pin B
J2, pins E and M
J2, pin H
J2, pins N and C
FL1 or FL2, pin B; to audio
accessory earphone
Chassis ground
A10, only in RT-505/PRC-15
V1 filament in RT-505/PRC-25
only when K2 is operated by
closure of audio accessory pushto-talk switch
K1 and K3
K1 and K2 to audio accessory
push-to-talk switch. Switch
operation will key K1 and K2
to set up receiver-transmitter in
transmit mode
Pins used depend on setting of S2
Pins used depend on setting of S2
Unit
CX-1029/VRC .. . . . . . . . . . . . . . . . .
MT-4723/VRC . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . .
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . .
AM-2060(*)/GRC . . . . . . . . . . . . . . . .
(1) Power distribution to OA-3633/GRC,
receiver-transmitter, and MX–2799/VRC or MX–
6707/VRC.
J3, pins J and Ca . . . . . . . . . . . . . . . .
Q1 and Q2 . . . . . . . . . . . . . . . . . . . . . .
Q3 and Q4 . . . . . . . . . . . . . . . . . . . . . . .
R17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
K1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver-transmitter . . . . . . . . . . . . . . . J3, pin B . . . . . . . . . . . . . . . . . . . . . . .
J3, pin A . . . . . . . . . . . . . . . . . . . . . . . .
J3, pin M . . . . . . . . . . . . . . . . . . . . . . . .
J3, pin H . . . . . . . . . . . . . . . . . . . . . . . .
J3, pin N . . . . . . . . . . . . . . . . . . . . . . . .
J3, pin C . . . . . . . . . . . . . . . .
CX-4722/VRC . . . . . . . . . . . . . . . . . Pins used depend on setting of S2 . . . . .
MX-2799/VRC or MX-6707/VRC . . . . . J551; pins used depend on setting of
S2.
• Indicates parallel connetions from J3, with CB1 in ON position.
(2) Power distribution through AM-1780
/VRC and crewmember control boxes.
Unit
From
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VBC . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . .
J21, pin B . . . . . . . . . . . . . . . . . . . .
Pin B . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J501, pin B . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S504, rear . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J22, pin D . . . . . . . . . . . . . . . . . . . . . . .
J3, pin J . . . . . . . . . . . . . . . . . . . . . . . . . . .
J24, pin C . . . . . . . . . . . . . . . . . . . . . . .
Pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J501, pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S504, front . . . . . . . . . . . . . . . . . . . . . . . . . . .
CB501 . . . . . . . . . . . . . . . . . . . . . . . . .
Pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J801, pin C . . . . . . . . . . . . . . . . . . . . . .
CB501 . . . . . . . . . . . . . . . . . . . . . . . . .
Pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .
J904, pin Cb . . . . . . . . . . . . . . . . . . . .
J904, pin Cb . . . . . . . . . . . . . . . . . . . . .
S901, rear . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . .
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . .
AM-2060(*)/GRC . . . . . . . . . . . . . . . . . . . . . .
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . .
C-2298/VRC . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . .
2297/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . .
To
J22, pin B
Pin B
S504, rear
J501, pin D
Pin D
J24, pin D
J3, pin C through CB1
J22, pin C
Pin C
S504, pin C
CB501
J504, pin C
Pin C
Amplifier A80
J505 (J506,J507), pin C
Pin C
Amplifier A80
S901, rear (EXT position)
J901, pin C
See footnote at end of table.
2-3
TM 11-5820-498-35
Cable (fig. 4-5, note 9) . . . . . . . . . . . . . .
C-2296/VRC . . . . . . . . . . . . . . . . . . . . . . .
a
b
To
From
Unit
Pin C . . . . . . . . . . . . . . . . . . . . . . . . . . .
J61, pin C . . . . . . . . . . . . . . . . . . . . . . .
Pin C
Amplifier A80
Indicates parallel connection from CB501.
Indicates parrallel connection from J904 pin C.
b. AM-1780/VRC MAIN PWR Switch at INT
ONLY. Under this arrangement, the radio circuit
Unit
is inoperative, and only the intercom circuit is operative.
From
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . .
J21, pin B . . . . . . . . . . . . . . . . . . . . . . .
Pin B . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J501, pin B . . . . . . . . . . . . . . . . . . . . . .
S504, front . . . . . . . . . . . . . . . . . . . . . . .
CB501 ª. . . . . . . . . . . . . . . . . . . . . . . . .
CB501 ª. . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . Pin C . . . . . . . . . . . . . . . . . . . . . . . . .
C-2298/VRC . . . . . . . . . . . . . . . . . . . . . . . J801, pin C . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . CB501ª . . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . Pin C . . . . . b. . . . . . . . . . . . . . . . . . . . . . .
C-2297/VRC . . . . . . . . . . . . . . . . . . . . . . J904, pin Cb . . . . . . . . . . . . . . . . . . . . .
J904, pin C . . . . . . . . . . . . . . . . . . . . .
S901, rear . . . . . . . . . . . . . . . . . . . . . . . .
Cable (fig. 4-4. note 9) . . . . . . . . . . . . . . . Pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-2296/VRC . . . . . . . . . . . . . . . . . . . . . . . J61, pin C . .
a
b
To
J22, pin B
Pin B
S504, front
CB501
Interphone amplifier A520
J504, pin C
Pin C
Amplifier A80
J505 (J506, J507) pin C
Pin C
Amplifier A80
S901, rear (EXT position)
J901, pin C
Pin C
Amplifier A80
Indicates parallel connection from CB501.
Indicates paallel connection from J904, pin C.
2-4. Receiver-Transmitter Control of Radio
Transmission and Microphone Signal Distribution, including Crewmember Control
Boxes
(fig. 4-5)
The crewmember control boxes (C-2296/VRC,
C–2797/VRC, and C–2298/VRC) provide a means
of keying the receiver-transmitter when the
audio accessory push-to-talk switch is set to radio
position. Simultaneously, the speech signals applied to the audio accessory microphone are applied through the crewmember control box, the
AM-1780/VRC, MT-1029/VRC, OA-3633(*)/
GRC, and the transmit circuits of the receivertransmitter to the antenna system.
Set
Intercommunication
a.Control,
C-2298/VRC.
(1) Circuit setup. Control of the receivertransmitter from the C-2298/VRC crewmember
boxes is possible when the AM-1780/VRC
Unit
RADIO TRANS switch S502 is set to CDR ONLY
or CDR + (plus) CREW, the INSTALLATION
switch is set to OTHER, the MAIN PWR Switch
is set to NORM, and the PWR CKT BKR switch
CB501 is set to ON. When the PWR CKT BKR
switch is set to ON, dc power is applied to the amplifiers A80 in the control boxes (fig. 4-5), to enable them to amplify the audio signals transmitted
from the crewmember audio accessories. Received
signals (para 2-5), either from the receivertransmitter or from other crewmembers in the
system, are not amplified in the intercom receive
circuits.
(2) Keying transmitter. When the audio accessory push-to-talk switch is depressed, a
ground is applied to the transmit circuits of the
receiver-transmitter, which, in turn, causes the
transmitter to set up for transmit mode in order
to permit speech signals ((3) below) to be applied to the distant radio station.
From
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . .
J802, pin C . . . . . . . . . . . . . . . . . . . . . .
S801 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin D . . . . . . . . . . . . . . . . . . . . . . . . . .
J504, pin D . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . .
MT-1029/VRC. . . . . . . . . . . . . . . . . . . . . .
S502 . . . . . . . . . . . . . . . . . . . . . . . .
S501 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin S . . . . . . . . . . . . . . . . . . . . . . . .
J22, pin S . . . . . . . . . . . . . . . . . . .
C-2298/VRC . . . . . . . . . . . . . . . . . . . . . .
See footnote at end of table.
2-4
To
S801 (ALL and A positions)
J801, pin D
Pin D
S502 (CDR ONLY or CDR +
CREW position)
S501 (OTHER and INT positions)
J501, pin S
Pin S
J24, pin S
TM 11-5820-498-35
Unit
From
....................
AM-2060-(*)/VRC
CX-4655/GRC . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver-transmitter . . . . . . . . . . . . . . . . .
a
J3, pin Ha . . . . . . . . . . . . . . . . . . . . . . . . . K1, terminal 5
J3, pin Ha . . . . . . . . . . . . . . . . . . .
J2, pill C
Pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin C
J3, pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Relay K3, terminal 5
Indicates parallel connection from J3, pin H.
(3) Radio transmission. After the receivertransmitter is keyed ((2) above), and the operator
at the C-2298/VRC talks into the microphone of
the audio accessory connected to J802, voice sig-
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . . . .
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . . . .
AM-2060(*)/VRC . . . . . . . . . . . . . . . . . .
CX-4655/GRC . . . . . . . . . . . . . . . . . . . . . .
Receiver-transmitter . . . . . . . . . . . . . . . .
nals are applied through the C-2298/VRC audio
the
then
and
through
amplifier
A80,
AM-1780/VRC to the transmit circuits of the receiver-transmitter.
From
Unit
C-2298/VRC . . . . . . . . . . . . . . . . . . . . . . . .
J802 or J803, pin D . . . . . . . . . . . . . . .
Amplifier A80, terminal 4 . . . . . . .
S801 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin K . . . . . . . . . . . . . . . . . . . . . . . . . . .
J504, pin K . . . . . . . . . . . . . . . . . . .
K502, terminal 4 . . . . . . . . . . . . . . . . .
Pin U . . . . . . . . . . . . . . . . . . . . . . . . . . .
J22, pin U . . . . . . . . . . . . . .
J3, pin N . . . . . . . . . . . . . . . . . . . . . . . .
Pin D . . . . . . . . . . . . . . . . . . . . . . . . . . .
J3, pin D . . . . . . . . . . . . . . . . . . . . . . . .
h. Control, Intercommunication Set C-2297/
VRC.
(1) Circuit setup. The circuit setup is the
one as given for the C-2298/VRC in a (1)
above.
(2) Keying transmitter. When the push-toUnit
From
J902, pin C . . . . . . . . . . . . . . . . . . . . . . . . . . .
S902 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J505 (J506, J507), pin D . . . . . . . . . . . . . . .
K501, terminal 3 . . . . . . . . . . . . . . . .
S502 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-1723/VRC . . . . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . .
CX-4725/VRC . . . . . . . . . . . . . . . . . . . . .
MT-1029/VDRC . . . . . . . . . . . . . . . . . . . .
AM-2060(*)/GRC . . . . . . . . . . . . . . . . . .
CX-4655/GBC . . . . . . . . . . . . . . . . . . .
Receiver-transmitter . . . . . . . . . . . . . . . .
To
Amplifier A80, terminal 2
S801
J801, pin K
Pin K
K502, terminals 2 and 4
J501, pin U
Pin U
J24, pin N
J2, pin D
Pin D
Module A22
talk switch of the audio accessory at connector
J902 is depressed, a ground is applied to the
transmit circuits of the receiver-transmitter,
which, in turn, causes the transmitter to setup for
transmit mode to permit speech signals ((8)
below) to be applied to the distant radio station.
C-2297/VRC . . . . . . . . . . . . . . . . . . . . .
a
To
S501 . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin S . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J22, pin S . . . . . . . . . . . . . . . . . . . . . . . . .
J3, pin Ha . . . . . . . . . . . . . . . . . . . . . . .
J3, pin Ha . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin C . . . . . . . . . . . . . . . . . . . . . . . .
J3, pin C . . . . . . . . . . . . . . . . . . . . . . . .
To
S902 (ALL and A positions)
J904, pin D
Pin D
K501, terminals 4 and 3
S502 (CDR + CREW position)
S501 (OTHER and INT ONLY
positions)
J501, pin S
Pin S
J24, Pin H
K1, terminal 5
J2, pin C
Pin C
K2, terminal 5
Indicates paralled connection from J3, pin H.
(3) Radio transmission. After the tranamittion is keyed ((2) above) and the operator at the
C-2297/VRC speaks into the microphone of the
audio accessory connected to J802, voice signals
are applied through the C-2297/VRC amplifier
A80, and through the AM-1780/VRC to the
transmit circuits of the receiver-trasmitter.
2-5
TM 11-5820-498-35
To
From
Unit
J902 or J903, pin D . . . . . . . . . . . . . . . Amplifier A80, terminal 2
Amplifier A80, terminal 4 . . . . . . . . . S902
J904, pin K
S902 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin K . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin K
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J505 (J506, J507), pin K . . . . . . . . . K502, terminals 13 and 12
K502, terminal 12 . . . . . . . . . . . J501, pin U
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . . Pin U . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin U
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . . J22, pin N . . . . . . . . . . . . . . . . . . . . . J24, pin N
AM-2060(*)/GRC . . . . . . . . . . . . . . . . . . J3, pin N . . . . . . . . . . . . . . . . . . . . . . . . J2, pin D
. . . . . . . . . . . . . . . . . . . . . Pin D . . . . . . . . . . . . . . . . . . . . . . . . . . Pin D
CX-4655/GRC
Receiver-transmitter . . . . . . . . . . . . . . . . . J3, pin D . . . . . . . . . . . . . . . . . . . . . . . . . Module A22
C-2297/VRC . . . . . . . . . . . . . . . . . . . . .
c. Control, Intercommunication Set
C - 2 2 9 6 / V R C . The C–2296/VRC is usually
mounted on the outside of the vehicle.
(1) Circuit setup. The circuit setup is the
same as given in a(1) above. In addition, the
OFF-EXT switch S901 in the C–2297/VRC must
be set to EXT. This operation permits communication from the C–2296/VRC to pass through the
C-2297/VRC into the intercom and radio system
circuits. It also lights the EXT lamp on the
Unit
C-2296/VRC .. . . . . . . . . . . . . . . . .
Cable (fig. 4-5, note 9) . . . . . . . . . . . . . .
C-2297/VRC . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . .
MT-1029/VRC . . . . . . . . . . . . . . . . . . . .
AM-2060(*)/GRC . . . . . . . . . . . . . . . . . . . . .
CX-4655/GRC . . . . . . . . . . . . . . . . . . . .
Receiver-transmitter . . . . . . . . . . . . . . . .
a
C-2297/VRC to alert the C-2297/VRC user that
the external C-2296/VRC is in the circuit.
(2) Keying transmitter. To communicate on
the radio system, the C-2296/VRC INT-RAD
TRANS switch S61 is set to RAD TRANS position. When the H–207/VRC push-to-talk switch is
depressed, a ground is applied to the transmit circuits of the receiver-transmitter, which, in turn,
causes the transmitter to set up for transmit
mode to permit speech signals ((3) below) to be
applied to the distant radio station.
From
To
TB61, pin 4 . . . . . . . . . . . . . . . . . . . . . .
S61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin H .. . . . . . . . . . . . . . . . . . .
J901, pin J . . . . . . . . . . . . . . . . . . . . .
J901 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S902 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin D . . . . . . . . . . . . . . . . . . . . . . . . . .
J506 (J506, J507), pin D . . . . . . . . .
K501, terminal 3 . . . . . . . . . . . . . . . . .
S502 . . . . . . . . . . . . . . . . . . . . . . . . . . .
S61 (RAD TRANS position)
J61, pin H
Pin H
S901 (EXT position)
S902
J904, pin D
Pin D
K501, terminals 4 and 3
S502 (CDR + CREW position)
S501 (OTHER and INT ONLY
positions)
S501 . . . . . . . . . . . . . . . . . . . . . . . . . . . J501, pin S
Pin S . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin S
J22, pin S . . . . . . . . . . . . . . . . . . . . J24, pin H
J3, pin Ha . . . . . . . . . . . . . . . . . . . . . . . K1, terminal 5
J3, pin Ha . . . . . . . . . . . . . . . . . . . . . J2, pin C
Pin C . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin C
J3, pin C . . . . . . . . . . . . . . . . . . . . . . . . K2, terminal 5
Indicates parallel connection from J3, pin H.
(3) Radio transmission. After the transmitter
has been keyed ((2) above) and the operator
speaks into the H–207/VRC microphone, voice
signals are applied through the C-2296/VRC amUnit
C-2296/VRC . . . . . . . . . . . . . . . . . . . . .
Cable (fig. 4-5, note 9) . . . . . . . . . . . . . . .
.................
C-2297/VRC
CX-4723/VRC . . . . . . . . . . . . . . . .
...................
AM-1780/VRC
See footnote at end of table.
2-6
plifier
A80,
the C-2297/VRC, and the
AM-1780/VRC to the transmit circuits of the receiver-transmitter.
From
To
TB61, pin 3 . . . . . . . . . . . . . . . . . . . . . . . . Amplifier A80, terminal 2
Amplfier A80, terminal 4 . . . . . . . . . J61, pin K
Pin K . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin K
J901, pin K . . . . . . . . . . . . . . . . . . . . . . S901, (EXT position)
S901 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S902
S902 . . . . . . . . . . . . . . . . . . . . . . . . . . . J904, pin K
Pin K
Pin K . . . . . . . . . . . . . . . . . . . . . . . . . .
K502, terminals 13 and 12
J505 (J506, J507), pin K . . . . . . . . . . . . . .
K502, terminal 12 . . . . . . . . . . . . . . . . J501, pin U
TM 11-5820-498-35
. . . . . . . . .. . . . . . .
CX-4723/VRC
.................
MT-1029/VRC
AM-2060(*)/GRC . . . . . . . . . . . . . . .
..................
CX-4655/GRC
Receiver-transmitter . . . . . . . . . . . . . . .
Pin U . . . . . . . . . . . . . . . . . . . . . . . Pin U
J22, pin U . . . . . . . . . . . . . . . . . . . . . . . . . . . J24, pin N
J3, pin N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J2, pin D
Pin D . . . . . . . . . . . . . . . . . . .
J3, Pin D . . . . . . . . . . . . . . . . . . . . . Module 22
2-5. Receiver-Transmitter Received Audio Signal Distribution, Including Crewmember
Boxes
(fig. 4-6)
Received audio signals from the receiver-transmitter are applied to the AM-2060(*)/GRC and
through the MT–1029/VRC, system cabling, and
the AM–1780/VRC, to the crewmember control
boxes (C-2296/VRC, C-2297/VRC, and C-2298/
Unit
Receiver-transmitter . . . . . . . . . . . . . .
.....................
CX-4655/GRC
AM-2060(*)/GRC . . . . . . . . . . . . . . . . . . .
VRC). Individual selector switches and volume
controls in the crewmember control boxes are
used to select the signal to be monitored, and to
adjust the audio signal level.
a. AM-2060 (*)/GRC Loudspeaker. Audio signals can be heard on the AM–2060(*)/GRC internal loudspeaker when the SPKR switch is set to
ON. Audio signals from the receiver-transmitter
are applied to the loudspeaker as follows:
From
Module A25/A55 . . . . . . . . . . . . . . . . . . .
Pin B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J2, pin B . . . . . . . . . . . . . . . . . . . . . . .
Audio amplifier Q1, Q2 . . . . . . . . . . .
S1 . . . . . . . .. . . . . . . . . . . . . . . . . . .
Relay K1, terminal 1 . . . . . . . . . . . . .
b. Unmuted Audio Signals to Crewmember
Control Boxes. When the crewmember control
box MONITOR switch is set to A position, unmuted (full strength) audio signals from the reItem
TO
From
Unit
To
J3, pin B
Pin B
Audio amplifier Q1, Q2
S1 (ON Position)
Relay E1, terminals 2 and 1
LS1 (through P1, J1)
ceiver-transmitter can be heard at the audio accessory at the crewmember control boxes. Unmuted audio signals are distributed to the crewmember control boxes as follows:
From
To
J3, pin B
Pin B
Audio amplifier Q1, Q2
J3, pin S
J22, pin H
Pin H
K501, terminals 9 and 10
J504, pin M
Pin M
S801 (A position)
R801 (VOLUME control)
J802 and J803, pins B and E to
audio accessory earphones
K501, terminal 10a . . . . . . . . . . . . . . . J505 (J506, J507), pin M
Pin M . . . . . . . . . . . . . . . . . . . . . . . . .
Pin M
J904, pin M . . . . . . . . . . . . . . . . . . . . . . S902 (A position)
S902b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R902 (VOLUME control)
R902 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J902 and J903, pins B and E to
audio accessory earphones
S902 b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S901 (EXT position)
J901, pin J
S901 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin J . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pin J
J61, pin J . . . . . . . . . . . . . . . . . . . . . . . . R61 (VOLUME control)
R61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . TB61, pin 5
TB61, pin 6 . . . . . . . . . . . . . . . . . . . . H-207/VRC earphone
Receiver-transmitter . . . . . . . . . . . . . . Module A25/A55 . . . . . . . . . . . . . . . . . .
CX-4655/GRC . . . . . . . . . . . . . . . . . . . . . . Pin B . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-2060(*)/GRC . . . . . . . . .
J2, pin B . . . . . . . . . . . . . .
Audio amplifier Q2 . . . . . . . . . . . . . . .
MT-1029/VRC . . . . . . . . . . . . . . . . . . . . . J24, pin S . . . . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . .
Pin H . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . J3, pin H . . . . . . . . . . . . . . . . . . . . . . . .
K501, terminal 10 . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . Pin M . . . . . . . . . . . . . . . . . . . . .
C-2298/VRC . . . . . . . . . . . . . . . . . . . . . . .
J801, pin M . . . . . . . . . . . . . . . . . . . . . .
S801 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
R801 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . . .
C-2297/VRC . . . . . . . . . . . . . . . . . . . . . . . . .
Cable (fig. 4-6, note 7) . . . . . . . . . . . . . .
C-2296/VRC . . . . . . . . . . . . . . . . . . . . . . . .
a
b
Indicates parallel connections from K501, terminal 10.
Indicates parallel connections from S902.
2-7
TM 11-5820-498-35
c. Muted Audio Signals to Crewmember Control Boxes. When a crewmember control box
MONITOR switch is set to ALL position, muted
audio signals (reduced strength by passage
through R15 in AM-2060(*)/GRC) can be heard
at the audio accessory at each crewmember control box. The receiver-transmitter audio signal is
reduced so that the intercom audio signals among
the crewmembers can be heard over the radio
audio signals, since both sources of audio signals
are avaiIable when the crewmember control box
MONITOR switch is set to ALL position. Muted
audio signals received at the receiver-transmitter
are distributed to the crewmember control boxes
as follows:
From
Unit
Receiver-transmitter . . . . . . . . . . . . . . . . . .
CX-4655/GRO . . . . . . . . . . . . . . . . . . .
AM-2060(*)/GRO . . . . . . . . . . . . . . . . . .
CX-4723/VRC . . . . . . . . . . . . . . . . . . . .
AM-1780/VRC . . . . . . . . . . . . . . .. . . . . . . .
CX-4723/VRC
...............
C-2298/VRC . . . . . . . . . . . . . . . . . . . .
Module A25/A55 . . . . . . . . . . . . . . .
Pin B . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J2, pin B . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Audio amplifier Q2 . . . . . . . . . . . . .
R15 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin K . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J501, pin K . . . . . . . . . . . . . . . . . . . . . . . . .
S503 . . . . . . . . . . . . . . . . . . . . . . . . . .
K502, terminal 19 . . . . . . . . . . . . . . . . .
Interphone amplifier A520a . . . . . . . . .
Pin L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J801, pin L . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S801 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
R801 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
AM-1780/VRC . . . . . . . . . . . . . . . . . . . . . . . . Interphone amplifier A520 . . . . . . . .
CX-4723/VRC . . . . . . . . .. . . . . . . . . Pin L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C-2298/VRC . . . . . . . . . . . . . . . . . . . . . . J904, pin L . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S902ª
. . . . . . . . . . . . .. . . . . . . . .
R 9 0 2 . . . . . . .. . . . . . . . . . . . . . . . . .
Cable (fig. 4-6, note 7) . . . . . . . . . . . . . . . . .
C-2296/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
b
S902 b . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S901 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pin J . . . . . . . . . . . . . . . . . . . . . . . . . . .
J61, pin J . . . . . . . . . . . . . . . . . . . . . . . . . .
R61 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TB61, pin 6 . . . . . . . . . . . . . . . . . . . . . . . . .
To
J9, pin B
Pin B
Audio amplifier Q1, Q2
R15 (muting resistor)
J9, pin K
Pin K
S608 (OFF position)
K502, terminals 18 and 19
Interphone amplifier A520
J504, pin L
Pin L
S801 (ALL position)
R801 (VOLUME control)
J802 and J809, pins B and E to
audio accessory earphone
J506 (J506, J507), pin L
Pin L
S902 (ALL position)
R902 (VOLUME control)
J902 and J903, pins B and E, to
audio accessory earphone
S901 (EXT position)
J901, pin J
Pin J
R61 (VOLUME control).
TB61, pin 5
H-207/VRC earphone
Indicates parallel connections from interphone amplifier A520.
Indicates paralled connections from S902.
Section II. RETRANSMISSION CIRCUIT FUNCTIONING
2-6. Radio Retransmission Circuits, General
(fig. 4-7 and 4-8)
a. The receiver-transmitter in the AN/VRC-53,
AN/VRC-64, AN/GRC-125, and AN/GRC-160
can be connected with another receiver-transmitter for the purpose of setting up a radio relay site
for automatic retransmission of radio signals
from radio stations that are too far distant from
each other for direct radio communication. The
other receiver-transmitter at the relay site can be
the RT-505/PRC-25 or RT-84/PRC-77 (para
2-7), or it can be the RT-246(*)/VRC or
RT-542(*)/VRRC
(para
2-6)
from
the
AN/VRC-12 radio series. (RT-246(*)/VRC and
RT-524(*)/VRC represent all models of each receiver-transmitter.)
b. Retransmission Cable Kit MK-456/GRC is
2-8
used to provide the connection between the receiver-transmitters at the relay site. The
MK-456/GRC consists of a canvas bag and a 50foot Cable Assembly, Special Purpose, Electrical
CX-4656/GRC. Two circuit boxes, a choke box,
and filter box (fig. 4-7) are included in the cable
assembly. An audio accessory can be connected to
the receptacle on the choke box to monitor audio
signals applied through the retransmission circuits. When the two radios at the relay site are
set up for providing retransmission to the two
distant radio stations, the keying of one relay site
receiver-transmitter to send the signals to one
distant radio station is automatically arranged by
the other relay site receiver-transmitter that i
receiving the signal from the other distant radio
station.
TM 11-5820-498-35
2-7 Retransmission Using RT-505/PRC-25’s or
RT-841/PRG-77's
a. Basic Setup. The CX-4656/GRC connection
between the two receiver-transmitters No. 2 and
No. 3 at the relay site is shown in note 5, figure
4-7. On the receiver-transmitters, the function
pitches are set to RETRANS. The distant radio
stations must be set up for squelch operation in
order to provide the automatic sending of the
150-Hz squelch signal when they are keyed for
transmission. When the relay site receiver-transmitters are set up for retransmission, the 150-Hz
squelch signal is used to operate relays for automatic retransmission and keying of the sending
receiver-transmitter.
b. Circuit Functioning. Under the setup in a
above, the retransmission circuits perform as
given in (1) through (8) below.
(1) Before a radio signal is received from
either distant radio station, the relay site receiver-transmitters are in standby mode. Under
this condition, the audio output transformers in
receiver amplifiers A25/A55 are grounded
through contacts of squelch relay K1 and function switch S1. Thus, no audio signals can pass
between the relay site radios.
(2) When a signal, including the 150-Hz
quelch signal, is received at receiver-transmitter
No. 2, it is applied through RF-IF amplifiers and
discriminator to receiver audio amplifier
A25/A55.
(3) From the discriminator, the 150/Hz
squelch signal is applied to squelch relay control
A24/A54. A24/A54 then provides a closed circuit
to operate relay K3. When K3 operates, contact
8-3 remove the short from audio output transformer in A25/A55 ((1) above).
(4) Simultaneously, ground on audio output
transformer in A25/A55 is provided through the
function switch and applied through the diode in
the CX-4656/GRC, and through receiver-transmitter No. 3 relays K1 and K2 to the battery.
Thus, contacts 4-7 of relay K1 provide 10 volts
operating power to receiver-transmitter No. 3
transmitting circuits.
(5) With the transmitting circuits in receiver-transmitter No. 3 in transmit mode, speech
signals now can be applied from receiver-transmitter No. 2 through the CX-4656/GRC to receiver-transmitter No. 3 speech amplifier A22,
and through the transmitting amplifier and P.A.
stages to the antenna for transmission to radio
station No. 4.
(6) When radio station No. 1 ceases keying
its transmitter, receiver-transmitters No. 3 and
No. 2 go into standby condition as described in
(1) above.
(7) When radio station No. 4 keys its transmitter and transmits its signals, receiver-transmitters No. 3 and No. 2 perform in the same
manner as described in (2) through (5) above.
(8) When an audio accessory is connected to
the audio accessory receptacle on the
CX-4656/GRC network box, the audio accessory
circuits are effectively connected to the output
audio circuits of receiver-transmitter No. 3 (the
one next to the choke box of the CX-4656/GRC
48 feet away). Accordingly, the audio accessory
user can perform the following operations.
(a) Hear the signal being transmitted
from radio station No. 4 to radio station No. 1.
(b) While receiver-transmitter No. 2 is
keyed (by squelch tone from No. 4), the user can
talk to radio station No. 1.
(c) If the radios are on standby, the user
can key (through pin C) and transmit (through
pin D) over receiver-transmitter No. 3 to No. 4.
The reply from radio station No. 4 will be heard
(through pin B). The action will also cause the
reply to be heard at radio station No. 1
(d) To transmit to radio station No. 1, the
user must transfer the audio accessory to the
AUDIO connector on receiver-transmitter No. 2,
which is next to the network box of the
CX-4656/GRC (2 feet away).
2-8. Retransmission Using ReceiverTransmitters r Radio RT-246(*)/VRC or
RT-524(*)/VRC With RT-505/PRC-25
or RT-841/PRC-77
NOTE
RT–246(*)/VRC and RT-524(*)/VRC represent all models of each receiver-transmitter.
When the RT-505/PRC-25 or RT-841/PRC-77 is
the
connected to
RT-246(*)/VRC or
RT-524(*)/VRC for retransmission, the circuit
performance of the radios during retransmission
is similar to that described in paragraph 2-7.
Refer to figure 4-8 for the following circuit functioning descriptions.
a. Basic Setup. The CX-4656/GRC connection
between receiver-transmitters No. 2 and 3 is
shown in figure 4-5. On receiver-transmitter No.
2, the function switch is set to RETRANS; on receiver-transmitter No. 3, the SQUELCH switch is
set to NEW ON or OLD ON, depending on the
radio station used at radio station No. 4.
b. Circuit Functioning. Under the setup in a
above, the retransmission circuits function as
given in (1) through (7) below.
2-9
TM 11-5820-498-35
(1) Before the RF signals are received from
either distant radio station, the relay site receiver-transmitters are in standby mode. Under
this situation, the output transformers, in
A25/A55 in No. 2 and T5001 in No. 3, are
grounded through contacts of their associated
squelch relays. Thus, no signals can pass between
the relay site receiver-transmitters.
(2) When a signal including the 150-Hz
squelch signal is received at receiver-transmitter
No. 2, it is applied through RF-IF amplifiers and
the discriminator to receiver audio amplifier
A25/A55.
(3) From the discriminator, the 150-Hz
squelch signal is applied to squelch relay control
A24/A54. A24/A54 then provides a closed circuit
to operate relay K3. When K3 operates, contacts
8-3 remove the short from output transformer in
A25/A55 ((1) above).
(4) Simultaneously, ground on the output
transformer in A25/A55 is provided through
function switch S1 and applied through diode
CR2 in the CX-4656/GRC and through receivertransmitter No. 3 relays K405 and K401 to the
25-volt battery. Thus, contacts 4-7 of K1 provide
operating power continuity to receiver-transmitter No. 3 transmitting circuits by the operation of
relays K405 and K401.
(5) With the transmitting circuits in receiver-transmitter No. 3 in transmit mode, speech
signals can now be applied from receiver-transthe
through
2 A25/A55
mitter No.
CX-4696/GRC to receiver-transmitter No. 3
transmit circuits, and to the antenna for transmission to radio station No. 4.
(6) When radio station No. 1 ceases keying
its transmitter, receiver-transmitters No. 2 and 3
go into standby condition ((1) above).
(7) When radio station No. 4 keys its transmitter and transmits its signals, the operation of
the circuits in receiver-transmitters No. 3 and 2
are accomplished as follows:
(a) When a signal including a squelch
signal (150-Hz or noise) is received at receivertransmitter No. 2, it is applied through the receive circuit.
(b) In the receive circuit, the squelch signal is applied to squelch control A5200, causing
squelch relay K5002 to operate. When K5002 operates, a ground is provided through contacts 2-5
of K505, CR303 (in RT–246(*)/VRC), or CR351
(in RT-524(*)/VRC), and the CALL lamp to the
25-volt battery.
(c) At the same time, the ground is pro-
2-10
vided through the CX-4656/GRC (pins E–C)
and relays K1 and K2 to the 12.5-15 volt batter
in receiver-transmitter No. 2.
(d) With the transmitting circuits in receiver-transmitter No. 2 in transmit mode by the
operations of K1 and K2, speech signals can now
be applied from T5005 in receiver-transmitter
No. 3 through the CX-4656/GRC (pins E-C) and
the transmitting circuits in receiver-transmitter
No. 2 to the antenna for transmission to radio
station. No.1.
(e) When radio station No. 4 ceases keying
its transmitter, receiver-transmitters No. 3 and 2
go into standby condition ((1) above).
(f) Diode CR1 in the C-E circuit of the
CX-4656/GRC is provided to keep the two different battery potentials separated when the receiver-transmitters No. 3 and 2 are in standby.
The diode prevents receiver-transmitter No. 2
from going into transmit mode by the operation
of K1 and K2. Under this condition, the circuit
performs as follows:
NOTE
If the CX-4656/GRC cable connects to the
receiver-transmitters shown in figure 4-8
diode CR2 in the C-E circuit would perform
the operations described for CR1 below.
1. When receiver-transmitter No. 2 is
connected to another RT-505/PRC-25 or
RT-841/PRC-77, a squelch signal received by No.
3 provides a simple ground to the battery in No. 2
which causes relays K1 and K2 to operate for
transmission (fig. 4-3 and para 2-7 b(4)).
2. However, when an RT–246(*)/VRC
or RT-524(*)/VRC is used as receiver-transmitter No. 3, there are two different battery potentials, 12.15 volts in No. 2 and 25 volts in No. 3.
If there were no diode CR1 in the CX-4656/GRC
when the receiver-transmitters are in standby,
the two batteries would be connected in series (B,
fig. 4-8). When two such opposing potentials
meet, a voltage difference (between 10 and 12.5
volts) would be sufficient to operate K1 and K2
into transmit mode in receiver-transmitter No. 2.
3. The diode in CX-4656/GRC preven
this extra voltage from operating K1 and K2. The
remaining voltage is blocked because the potential (which takes on the polarities of the 25-volt
battery) would apply a negative potential to the
anode of the diode. Thus, no current can flow
operate K1 and K2 in receiver-transmitter No. 2.
TM 11-5820-498-35
Section Ill. AMPLIFIER-POWER SUPPLY GROUP
OA-3633(*)/GRC, CIRCUIT FUNCTIONING
2-9. Amplifier-Power Supply AM-2060(*) /
GRC, Block Diagram
(fig. 2-1)
The AM-2060(*)/GRC is the main component of
the OA-3633(*)/GRC; the other component is
Cable Assembly, Special Purpose, Electrical
CX-4656/GRC (para 2-11, fig. 3-5). The
CX-4656/GRC provides dc power and audio signal connection between the receiver-transmitter
and the AM-2060 (*)/GRC. The
AM-2060(*)/GRC converts vehicular battery
power (24 ±3 volts dc) to the operating voltages
for the receiver-transmitter (a below), and amplification of the receiver-transmitter received
audio signals for application to the loudspeaker
in the AM–2060(*)/GRC (c(1) below), and to
the crewmember control boxes when they are a
part of the system (c(2) below). The vehicular
battery power is also applied to Antenna Matching Unit MX–2799/VRC (part of Antenna
AT-912/VRC) or to Matching Unit-Base, Antenna MX-6707/VRC (part of Antenna
AS-1729/VRRC) (b below).
a. Operating Voltages to Receiver-Transmitter.
The nominal 25.5 volts dc from the power source,
normally a vehicular battery, is applied through
the MT-1029/VRC and PWR circuit breaker CB1
to series regulator Q3 and dc amplifier Q4, voltage dropping resistor R17, ANT. FREQ. CONTROL switch S2, and audio amplifiers Q1 and Q2.
(1) Series regulator Q3 and dc amplifier Q4
convert and control the applied 25.5 volts dc to a
regulated 13 and 3 volts dc. The 13 volts is for
use in the receiver-transmitter where it is converted to 10 volts for the transmit and receive
circuits. In the RT-505/PRC-25 only, the 3 volts
dc is used for interval oscillator A10.
(2) Voltage dropping resistor R17 lowers
the applied 25.5 volts dc to 2.6 ±0.3 volts dc.
This voltage is used only in the RT-505/PRC-25
as filament voltage for power amplifier V1 when
the RT-505/PRC-25 is in transmit mode.
b. Operating V o l t a g e s A p p l i e d t o M X 2799/VRC and MX-6707/VRC. The nominal
25.5 volts dc is applied through ANT. FREQ.
CONTROL switch S2 to the MX-2799/VRC or
MX-6707/VRC. The voltage is used by the
MX-2799/VRC and MX-6707/VRC to control the
settings of the matching circuits to provide a
close impedance match for the whip antenna at
the operating frequency of the receiver-transmitter. Switch S2 is set to a position that includes
the receiver-transmitter operating frequency.
c. Audio Amplifiers Q1 and Q2. The audio output of the receiver-transmitter is applied to audio
amplifiers Q1 and Q2.
(1) Remote audio output. Amplifiers Q1 and
Q2 amplify the audio signals applied to it from
the receiver-transmitter and provide two outputs,
muted and unmuted. The output signals are applied to crewmember control boxes when they are
part of the system.
(2) Local audio output. The amplifier audio
signals from Q1 and Q2 are also applied through
SPKR switch S1 to receive-transmit relay K1.
When the receiver-transmitter is keyed for transmission, the keying relay in the receiver-transmitter is operated which causes +13 volts dc to
be applied to the winding of keying relay K1 in
the AM-2060(*)/GRC. When K1 operates, it disconnects the audio signal from the loudspeaker,
and thus prevents feedback from the loudspeaker
to the audio accessory microphone.
2-10. AM-2060(*)/GRC, Circuit Functioning
a. Audio Amplifiers Q1 and Q2. Q1 and Q2
provide amplification of the audio output signals
from the receiver-transmitter. The amplified
audio output is applied to the AM–2060(*)/GRC
loudspeaker and to the audio accessories of the
associated crewmember control boxes.
(1) The audio output signal at pin B of SET
POWER connector J2 is coupled through impedance matching transformer T1 to the base of
push-pull amplifiers Q1 and Q2. The amplified
audio output is applied to the primary (terminals
1 and 3) of transformer T2. The audio output
across one-half of the secondary of T2 (terminals
4 and 5) is coupled through SPKR switch S1
(ON position) and relay K1 (contacts 8 and 2) to
loudspeaker LS1. The audio output across the
secondary of T2 (terminals 4 and 6) is applied
through limiting resistor R15 to pin K of
POWER INPUT connector J3 to provide a muted
audio output; and to pin S of J3 to provide an unmuted audio output to the crewmember control
boxes.
(2) A voltage-dividing network, composed
of resistors R2 and R3, and temperature-compensating thermistor RT1 provide base-to-emitter
bias for Q1 and Q2. Thermistor RT1 has a nega2-11
TM 11-5820-498-35
Figure 2-1. Amplifier-Power Supply AM-2060(*)/GRC, block diagram.
tive temperature coefficient to compensate for
temperature variations during operation. Resistors E1 and R4 provide negative feedback to the
base of Q1 and Q2 to control the gain of the amplifier. Resistors R7 and R8 prevent current saturation of Q1 and Q2.
(3) A +13-volt dc output from the receivertransmitter is applied to contact 1 of relay K1
through pin N of connector J3. When the receiver-transmitter is keyed, a ground is applied
through pin C of J3 to energize K1. When K1 is
energized, loudspeaker M1 is disconnected from
the circuit, and a remote muting path (pin D of
J3) is grounded through closed contacts 4 and 7.
Energizing relay K1 mutes any audio accessory
at the crewmember control boxes. When LS1 is
disconnected from the circuit (K1 energized), re
sisters R12 and R13 act as a load for the secondary of transformer T2. When the SPKR switch is
2-12
at OFF, resistor R16 acts as the output load for
the audio amplifier through closed contacts 2 and
3 of S1. Resistors R14 and R18 provide impedance matching for the audio accessories at the
crewmember control boxes.
b. Series Regulator Q3 and Dc Amplifier Q 4 .
Series regulator Q3 and dc amplifier Q4 reduce
the 25.5-volt dc power from the vehicular battery
to 13 volts and 3 volts dc, and regulates these
voltages. The 13 volts dc is applied to the RT505/PRC-25 or RT-841/PRC–77; the 3 volts
dc is used only by the RT-505/PRC-25.
(1) The +25.5-volt dc input at pin J or
POWER INPUT connector J3 is applied through
CB1, bias resistor R5 to the collector of Q3, and
bias resistor R6 to the base of Q3 and the collector of Q4. The regulated +13 volts that appear:
across filter capacitor C1 is applied to pin E of
SET POWER connector J2. The regulated +3
TM 11-5820-498-35
volts that appears across resistor R19 is applied
to pin M of connector J2.
(2) Bias for Q4 is supplied from a voltagedividing network composed of R9, R10, R11, and
R19 connected between the collector of Q3 and
ground. Diode CR1 references the emitter of Q4
to ground. Diode CR2 references the base of Q4
to the + 13-volt output. Regulating action is described in (3) below.
(3) If the input voltage to Q3 decreases, the
13-volt output decreases. Capacitor C1, charged
to the 13-volt level, will begin to discharge as the
output voltage drops, tending to maintain a constant output until the regulating action occurs.
As the output voltage decreases, the voltage drop
across R9, R11, and R19 decreases, reducing forward bias on Q4, which will decrease its emitterto-collector current flow. The reduced emitter-tocollector current of Q4 reduces the voltage drop
across resistor R6, increasing the forward bias of
Q3. Emitter-to-collector current flow in Q3 will
increase, decreasing emitter-to-collector resistance. The voltage drop through Q3 will decrease
and allow the output to return to the desired level
of 13 volts. If the supply voltage increases to the
normal 25.5-volt level, Q4 will decrease the forward bias on Q3 to maintain the constant 13-volt
output. Resistor R10 is adjusted to produce the
required 13-volt output from the voltage regulator.
c. ANT. FREQ. CONTROL Switch S2. T h e
+25-volt dc input at pin J of POWER INPUT
connector J3 is applied through PWR circuit
creaker CB1 and switch S2 to the MX–2799/VRC
of the AT–912/VRC or to MX-6707/VRC of the
AS-1729/VRC, whichever is connected to the
AM–2060(*)/GRC. Switch S2 is set to the position corresponding to the operating frequency of
the associated receiver-transmitter. Capacitors
C1 through C7 bypass radio frequency (RF) from
the MX–2799/VRC or MX–6707/VRC to ground.
2-11. Cable Assembly, Special Purpose,
Electrical CS-4655/GRC
(fig. 3-5)
The CX-4655/GRC (9 or 11 inches long) and the
AM-2060(*)/GRC comprise the OA-3633(*)/
GRC. The CX-4655/GRC is provided with two cable connectors either of which is connected to
the SET POWER connector on the
AM–2060(*)/GRC; the other end of the cable is
connected to POWER connector J3 on the receiver-transmitter. The cable carries power, control circuits, and audio signal circuits between
the AM–2060(*)/GRC and the receiver-transmitter.
2-13
TM 11-5820-498-35
CHAPTER 3
DS AND GS MAINTENANCE
AMPLIFIER-POWER SUPPLY GROUP OA-3633(*) /GRC
NOTE
Throughout these procedures, receiver-transmitter refers to Receiver-Transmitter, Radio
RT–505/PRC-25 which is used in Radio Sets
AN/VRC-53 and AN/GRC-125, and to Receiver-Transmitter, Radio RT-841/PRC-77
which is used in Radio Sets AN/VRC-64 and
AN/GRC-160. Both receiver-transmitters
are used with Amplifier-Power Supply
Group OA-3633(*)/GRC which is also part of
these radio sets.
Section I. GENERAL TROUBLESHOOTING TECHNIQUES
3-1. Scope of DS and GS Maintenance
a. The maintenance procedures in this chapter
are applicable to DS (direct support) and GS
(general support) maintenance facilities and supplement the organizational maintenance procedures described in TM 11-5820-498-12 for the
OA-3633(*)/GRC. The systematic troubleshooting procedures which begin with the operational
and equipment performance checks that can be
performed at an organizational maintenance level
are carried to a higher level in this chapter.
b. Refer to paragraph 1-lb for a listing of
publications that cover the DS and GS maintenance level of the components that are part of
the AN/VRC-53, AN/VRC-64, AN/GRC-125,
and AN/GRC–160.
c. Refer to paragraph 1-1c for a listing of publications that cover the DS and GS maintenance
level of the equipment that is used in conjunction
with these radio sets.
3-2. Organization of Troubleshooting Procedures
a. General. The first step in servicing a defective OA-3633*/GRC is to localize the fault by
tracing the trouble to the CX-4655/GRC or to
some part of the AM–2060(*)/GRC. The second
step is to isolate the fault. Isolation means tracing the fault to a defective part responsible for
the abnormal operation. Isolating a fault to a defective part on the plug-in assembly of the
AM-2060(*)/GRC is covered in Paragraphs 3-8,
3-9, and 3-10. Some faults, such as burned out
resistors, arcing, and shorted relay coils and
transformer windings can often be located by
sight, smell, or hearing. The majority of the
faults, however, must be isolated by checking
voltages and resistances.
b. Visual Inspection. The purpose of visual
inspection is to locate faults without testing or
measuring circuits. All visual signs should be observed and an attempt made to localize the fault
to a particular area.
c. Testing Procedure. After any repair of the
CX-4655/GRC or AM-206(*)/GRC, always test
it for satisfactory performance of all circuits before returning the equipment to the user or placing it in repaired stock. Refer to paragaphs 3-16
through 8-21 for inspection and testing procedures. The procedures can also be used to check
the performance of the equipment before starting
to troubleshoot it.
3-3. Test Equipment, Tools, Materials, and
Power Sources Required
a. Test Equipment Required.
Publication
Item
a
Multimeter ME-26(*)/U . . . . . . .
TM 11-6625-200-15
TM 11-6625-683-15
Generator, Signal AN/URM-127
Voltmeter, Electronic
M E - 8 0 ( * ) / U b . . . . . . . . . TM 11-6625-820-12
Change 2
3-1
TM 11-5820-498-35
Publication
Item
Spectrum Analyzer
TS-723(*)/U a
a
b
ME-30(*)/U represents ME-30A/U, ME-30B/U, ME-30C/U, a
ME-30E/U.
a
TS-723(*)/U represents TS-723A/U, TS-723B/U, TS-723C/U,
TS-723D/U.
TM 11-5097
ME-26(*)/U represents ME-26A/U, ME-26B/U, and ME-26C/U.
Item
b. Materials and Tools Required.
Federal stock No.
Resistor, 7.6 ohms (e below).
Resistor, 275 ohms (e below).
Resistor, 14.5 ohms (e below) . . . . . 5905-279-3521
Resider, 300 ohms (e below) . . . . . . . . . 5905-101-8850
5820-893-1323 . . . . . . . . . . . . . . . . . . .
Mounting MT-1029/VRC . . . . . .
Cable Assembly, Power, Electrical CX- 5995-823-2726 . . . . . . . . .. . . . . . . . . . .
4720/VRC (10 ft).
Cable Assembly, Special Purpose, Elec- 5995-889-1061 . . . . . . . . . . . . . . .
trical CX-4655/GRC (e below).
5935-863-5876 . . . . . . . . . . . . . . . . . . . .
Connector, receptacle, electrical (male,
oval; same as J21 in MT-1029/VRC).
Connector, receptacle, electrical (female, 535-853-5944 . . . . . . . . . . . . . . . . . . . .
oval; same as J23 in MT-1029/VRC.
Connector, receptacle, electrical (female, 5935-853-6044. . . . . . . . . . . . . . . . . . . .
elliptical; same as J24 in MT-1029/
VRC).
Tool Kit, Electronic Equipment TK100/G.
Tool Kit, Electronic Equipment TK106/G.
Identified in
TM 11-5820-498-12
TM 11-5820-498-12
TM 11-5820-498-12
TM 11-5820-401-35
TM 11—5820-401-35
TM
11-5820-401-35
Notes
MT-1029/VRC is required if a fabricated power distribution box (d below) is not avaailable.
For fabrication of power distribution box (d below as substitute for the MT-1029/VRC.
c. Power Source Required. (1) Power Supply
PP-6224/U or
PP-2953(*)U maybe used
to provide the operating dc voltage for the
AM-2060(*)/GRC. The PP-2952(*)/U is normal
internally adjusted to provide 25.2 volts dc output
(TM 11-6130-233-12.)
(2) If a dc power source other than the
ones in (1) above
is used, it should be
capable of providing a regulated, filtered, dc output of 25.5 volts dc at approximately 5 amperes.
(3) If the area in which the testing is being
performed has difficulty in obtaining an ac power
source that is within the operating ac input voltage of the PP-2953(*)/U or other power supply),
use Variable Power Transformer TF-523/U (fig.
3-3). Refer to TM 11-5950-212-15 for installation and maintenance of the TF-523/U.
d. Power Distribution Box. As a substitute for
the MT–1029/VRC which is only used as a connecting device between the dc power source and
the AM-2060(*)/GRC during testing and troubleshooting, a power distribution box may be fabricated. Refer to paragraph 3-4b for fabrication details.
e. Transmit and Receive Dummy Load Assemblies. Fabricate two dummy load assemblies to imitate the transmit and receive states of the receiver-transmitter that would be connected to the
3-2
Change 2
AM-2060(*)/GRC SET POWER connector
through the CX-4655/GRC.
(1) Remove the two connector plugs from the
CX-4655/GR C (b above).
(2) Designate one of the connector plugs as
the transmit dummy load assembly, and correct
the load resistors (b above) as shown in figure
3-1.
(3) Designate one of the connector plugs as
the receive dummy load assembly, and connect
the load resistors (b above) as shown figure 3-1.
3-4. Connecting Dc Power to AM-2060(*) /
GRC
There are two methods for connecting dc power to
the AM-2060(*)/GRC. One method is to use the
MT-1029/VRC (a below): the other method is to
use a fabricated power distribution box ( b
below).
CAUTION 1
Before making dc power connection make
sure the dc power supply POWER switch and
the PWR switch on the AM-2060(*)/GRC
are set to off.
CAUTION 2
If the CX-4720/VRC power cable is used
(a(2) and b(4) below), make sure the redwhite leads are connected to plus (+) ter-
TM 11-5820-498-35
NOTE
The PP-2953(*)/U is normally internally adjusted for 25.2 volts dc output (TM
11-6130-233-12). Throughout this manual, a
dc power source of 25.5 volts dc is indicated.
Accordingly, if the PP-2953(*)/U is used,
25.2 volts dc should be measured where 25.5
volts is mentioned.
Figure 3-1. Fabrication of transmit and receive dummy
load assemblies.
minal of the dc power supply, and the bluegreen leads are connected to the minus (-)
terminal of the dc power supply.
a. Using Mounting MT–1029/VRC. Before using
the MT-1029/VRC, check to see that the link in
the connecting box is positioned as shown in
figure
3-2
for
directing
power
to
the
AM-2060(*)/GRC.
NOTE
If the link were positioned between pivot and
terminal E22 as shown in dashed lines in
figure 3-2, no power would be applied to the
AM-2060(*)/GRC when the PWR switch is
set to ON. (See MT-1029/VRC in figure 44.).
(1) Using PP-2953 (*)/U.
(a) If the PP-2953(*)/U is used, connect
CX-4721/VRC between the PP–2953(*)/U
d the MT–1029/VRC as shown in figure 3-3.
NOTE
Since the PP-2953(*)/U can supply up to approximately 10 amperes, two OA-3633(*)/
GRC may be tested at the same time, including receiver-transmitted, as shown in
figure 3-3.
(b) Connect the PP-2953(*)/U to the ac
power source.
NOTE
If the TF-523/U is required (para 3-3c),
connect it between the ac power source and
the PP-2953(*)/U as shown in figure 3-3.
Refer to TM 11-5950-212-15 for instructions
to modify the PP-2953(*)/U’s CX-4524/U
for use with the PP-2953(*)/U. Set the TF523/U POWER switch to OFF and the
VOLTS ADJUST control fully counterclockwise (O volt output) before making connections.
(c) Lay the AM-2060(*)/GRC on the
MT-1029/VRC and push it back until the connectors are fully together. Fully tighten the
MT-1029/VRC mounting clamps to hold the
AM-2060(*)/GRC in place.
NOTE
A receiver-transmitter can be mounted on the
AM-2060(*)/GRC and connected to it using
the CX-4655/GRC.
(d) To turn on the equipment, set the
PP-2953(*)/U AC and DC power switches to ON;
the NORM indicator lamp should light. Set the
PWR switch on the AM-2060(*)/GRC to ON
when desired. If the TF-523/U is used, set its
POWER switch to ON and adjust the control until
the voltmeter indicates 115 volts. The amount of
current drawn by the equipment will be shown on
the ammeter.
(2) Dc power source other than PP-2953
(*)/U.
(a) If a dc power source other than the
PP–2953(*)/U is used ((1) above), connect the
MT–1029/VRC to the dc power source; use the
CX-4720/VRC (fig. 3-3). (See caution 2 above.)
(b) Lay the AM-2060(*)/GRC on the
MT-1029/VRC and push it back until the
AM–2060(*)/GRC and MT-1029/VRC connectors
are
together.
firmly
Fully
tighten the
MT-1029/VRC mounting clamps to hold the
AM–2060(*)/GRC in place.
NOTE
A receiver-transmitter can be mounted on the
AM–2060(*)/GRC and connected to it using
the CX-4655/GRC.
3-3
TM 11-5820-498-35
Figure 3-2. View of MT-1029/VRC connector box with cover removed showing position of link.
(c) Turn on and adjust the output of the dc power
supply to 25.5 volts. Set the PWR switch on the AM2060(*)/GRC to ON when desired.
b. Using Fabricated Power Distribution Box (fig. 34). When the MT-1029/VRC is not available, dc power
may be applied to the AM-2060(*)/GRC through a
power distribution box, fabricated and used as
follows:
(1) Obtain the MT-1029/VRC oval power receptacles J21 (male) and J23 (female), and the elliptical
power receptacle J24 (para 3-3b).
(2) Fabricate a small, sturdy, metal box large
enough to mount the two oval receptacles and the
elliptical receptacle. Mount the oval receptacles on
34 Change 2
the rear of the box, and the elliptical receptacle on
the front of the box (fig. 3-4).
(3) Interconnect the following pins of the receptacles; use insulated # 14 AWG wire:
(a) Interconnect pins A(+) and B(-) of the oval
receptacles.
(b) Interconnect pins A and B of one of the
oval receptacles with pins A and J of the elliptical
receptacle.
(4) To make the power connections, proceed as
follows:
(a) Turn off the dc power supply being used
and connect the CX-4720/VRC to it; see caution 2
above. Connect the other end of the
TM 11-5820-498-35
Figure 3-3. Connecting power to OA-3633/GRC using PP-2953(*)/U and TF-523/U.
CX-4720/VRC to the male receptacle on the power
distribution box (D, fig. 8-4).
(b) Connect the elliptical receptacle on the
power distribution box to POWER INPUT receptacle on the rear of the AM-2060(*)/GRC.
(c) The female receptacle on the power
distribution box may be connected to another
piece of equipment using the CX-4721/VRC.
(d) Turn on and adjust the output of the dc
power supply to 25.5 volts. Set the PWR switch on
the AM–2060(*)/GRC to ON when desired.
Section II. OA-3633(*)/GRC, TROUBLESHOOTING PROCEDURES
3-5. Troubleshooting OA-3633(*)/GRC
a. When the AM–2060(*)/GRC resistors R6, R7,
and R8 (fig. 3-18) are charred, there will be no
audio output from the AM–2060(*)/GRC t O the
receiver-transmitter. These charred resistors usually indicate that the power cable in the vehicle
(usually the CX-4720/VRC) in which the
AM-2060(*)/GRC had been used, had been connected incorrectly to the vehicular battery. That
is, the CX-4720/VRC negative leads (blue-green)
had been connected to the battery positive terminal, and the positive leads (red-white) had been
connected to the battery negative terminal. To
prevent incorrect battery connections, the following precautionary procedures are recommended:
(1) Mark the battery terminals of the vehicular battery power cable so that the person that replaces the cable leads to the battery knows the
positive power cable lead(s) and the negative
power cable lead(s). The battery negative terminal can be identified by the fact that it is smaller
than the positive battery terminal and it is connected to the vehicular chassis by a bonding strap.
(2) Install Suppressor, Electrical MX7778/GRC in the battery distribution circuit
of the vehicle. Installation procedures are provided in TM 11–5195-223-15, which also covers
maintenance of the suppressor. T h e M X 7778/GRC protects the vehicle from circuit
overload (short circuit) in the radio (and intercom) equipment and the radio (and intercom)
equipment from electrical transient voltages in
the vehicle electrical system.
b. When trouble is suspected in the application
of operating dc voltages to the receiver-transmitter that was used with the AM-2060(*)/GRC,
check the AM–2060(*)/GRC output circuits by
performing measurements of the output voltages
and resistances at connector J2 (para 3–8, fig.
3-6).
c. When trouble is suspected in the audio ampli3-5
TM 11-5820-498-35
Figure 3-4. Fabrication and connection of power distribution box.
3-6
TM 11-5820-498-35
fier circuits, check the circuits of the audio amplifiers (para 3-9).
3-6. Troubleshooting Chart
The trouble symptoms listed in the following
troubleshooting chart will aid in localizing and
isolating troubles to a component part in the
AM–2060(*)/GRC.
3-7
TM 11-5820-498-35
NOTE:
CONNECTORS VIEWED FROM PIN SIDE.
TM5020-498-35-6
Figure 3-5. Cable Assembly, Special Purpose, Electrical CX-4655/GRC, wiring diagram.
3-7.
Continuity and Short Circuit Tests for
Cable Assembly, Special Purpose, Electrical CX-4655/GRC
Use Multimeter ME-26(*)/U as an ohmmeter to
check for continuity and short circuits in
CX-4655/GRC wires. Refer to figure 3–5 for the
wiring diagram.
3-3. AM-2060(*)/GRC, Voltage and
Resistance Measurements at Connectors
J2, J3, and J4
To isolate trouble to a defective part in the
AM-2060(*)/GRC, other than on the plug-in assembly, use the techniques given in a through c
below. Use the schematic diagram (fig. 4-9) to
trace and isolate the defective part.
a. Resistance Measurements Before making resistance measurements, remove all power and
cable connections to the AM-2060(•)/GRC. Refer
to figure 3-6 for the required AM-2060(*)/GRC
3-8
switch settings and resistance indications. Refer to
c below for the resistance indications at all switch
positions of the ANT. FREQ. CONTROL switch.
b. Voltage Measurements. To make voltage
measurements, apply a 25.5-volt dc power source
(or 25.2 volts from the PP-2953(*)/U)to POWER
INPUT connector J3 (para 3-4). Refer to figure
3-6 for the required AM–2060(*)/GRC switch settings and voltage indications. Refer to c below for
the voltage indications at all positions of the ANT
FREQ. CONTROL switch.
c. ANTENNA CONTROL Connector J4. Voltage
(b above) and resistance (a above) indications at
connector J4 for all positions of ANT. FREQUENCY CONTROL switch are provided in the
following chart. The SPKR switch is set to OFF;
the PWR switch is set to ON. The ME-26(*)/U
measurements are made between J4 pins and
ground.
TM 11-5820-496-35
3-9. AM-2060(*)/GRC, Isolating Troubles in
Audio Amplifiers Q1 and Q2
When trouble has been localized to audio amplifiers Q1 and Q2, use the following procedures
to isolate the defective part in the circuit.
a. The following equipment is required:
(1) A 25.5-volt dc power source (or 25.2-volt
output of Power Supply PP–2953(*)/U).
(2) Generator, Signal AN/URM-127.
(3) Voltmeter, Electronic ME-30(*)/U.
(4) Receive dummy load assembly (para
3-3e, fig. 3-1).
b. Remove the access plate (fig, 3–10) from the
top of the AM–2060(*)/GRC to gain access to the
test points El through E22 on the plug-in assembly (fig. 3-11 and 3-15).
c. Connect the receive dummy load assembly to
SET POWER connector J2 (fig. 3-7).
d. Connect the dc power source (a(1) above) to
pins A (chassis ground) and J of POWER INPUT
connector J3 (fig. 3–7).
e. Set the PWR and SPKR switches to ON.
f. Apply a 1-kHz, 1-volt signal from the
AN/URM-127 with its adapter UG–514/U to pins
A (chassis ground) and B of SET POWER
connector J2 (fig. 3-7).
g. When the ME–30(*)/U is connected between
pins E1 and E14 of the plug-in-assembly (fig.3-9),
it should indicate 4.5 ± 0.10 volts ac. If the
ME-30(*)/U indication is not approximately 4.5
volts ac, make voltage and resistance measure
ments of the audio amplifier circuit and also the
voltage regulator circuit.
(1) To make the voltage measurements, leave
the dc power connected to connector J3 (d above)
and make the voltage measurements at the pins of
the plug-in assembly (fig. 3–9).
(2) TO make the resistance measurements,
remove the dc power from connector J3, and make
the resistance measurements at the pins of the
plug-in assembly.
(3) Refer to paragraph 3-11 for dc resistance of transformers and coils involved in the
circuits.
3-10. AM-2060(*)/GRC, Adjustment of R10,
and Isolating Troubles in Voltage Regulator Circuits Q3 and Q4
When trouble has been localized to voltage regulators Q3 and Q4, use the following procedures to
isolate the defective part in the circuit.
a. Equipment Required.
(1) A 25.5-volt dc power source (or 25.2volt output of Power Supply PP-2953(*)/U).
(2) Multimeter ME-26(*)/U.
(3) Transmit dummy load assembly (para
3-3e, fig. 3-1).
b. Test Setup.
(1) Remove the access plate (fig. 3-10)
from the top of the AM–2060(*)/GRC to gain access to the test points El through E22 on the
plug-in assembly (fig. 3-9).
(2) Connect the transmit dummy load assembly to SET POWER connector J2 (fig. 3–8).
(3) Connect the dc power source (a(1)
above) to pins A (chassis ground and J of
POWER INPUT connector J3 (fig. 3-8).
(4) Set the PWR switch to ON.
c. Output Voltage Adjustments, R1O.
(1) Perform the test setup given in b above.
(2) Connect the ME-26(*)/U, arranged as a
dc voltmeter, between pins E (positive) and A
(chassis ground) (14.5-ohm load resistor) of
SET POWER connector J2 (fig. 3–8).
(3) Loosen the locknut holding the adjustment screw of R10 (fig. 3–11).
NOTE
If the locknut cannot be easily loosened, use
a drop of penetrating oil on the threads and
allow it to penetrate before trying to loosen
the locknut.
(4) Adjust R10 adjustment screw for an indication of +13 volts on the ME-26(*)/U. Fingertighten the locknut holding the control.
d. Isolating Troubles in Voltage Regulator Circuit Q3 and Q4.
(1) Perform the test setup and adjustment
procedures given in b and c above before proceeding.
(2) Measure the voltage drop across reference diode CR1 by placing the ME-26(*)/U negative lead on test point E1 and the positive test
lead on test point E6 (fig. 3-9). The ME-26(*)/U
should indicate approximately 6.8 volts dc.
(3) Measure the voltage drop across reference diode CR2 by placing the ME–26(*)/U
negative lead on test point E3 and the positive
test lead on test point E4. The ME–26(*)/U
should indicate approximately 6.8 volts dc.
(4) If the voltage indication obtained across
CR1 and CR2 is still not within limits, make voltage and resistance measurements of the voltage
regulator circuits to determine the defective part.
3-11. Dc Resistance of Transformers and Coils
The dc resistance of the transformer windings
and the relay coil on the plug-in assembly of
the AM-2060(*)/GRC are listed in the following
chart.
3-9
TM 11-5820-498-35
Figure 3-6. AM-2060(*)/GRC, front and rear panel connectors J2, J3, and J4,
voltage and resistance indications.
NOTE
Make all resistance measurements with the
plug-in assembly removed from the
AM-2060(*)/GRC (para 3-13a).
3-10
Change 1
TM 11-5820-498-35
Figure 3-7. Test setup for isolating trouble in audio amplifiers Q1 and Q2.
3-11
TM 11-5820-498-35
3-12
TM 11-5820-498-35
Section lll. OA-3633(*)GRC, PARTS REMOVAL AND
REPLACEMENT PROCEDURES
3-12. General
a. Most of the parts of the AM-2060(*)/GRC
may
be
easily
reached,
and
replaced
within the equipment without special procedures.
Paragraphs 3-13 through 3-15 contain removal
and replacement procedure for those parts of
the AM-2060(*)/GRC which are not obvious or
which require precautionary procedures.
b. No special tools are required, except that in
removing transistors and diodes, use a pencil-type
soldering iron with a 25-watt maximum capacity.
With a pair of long-nose pliers, grasp the lead between the transistor or diode and the solder connection to dissipate the soldering iron heat.
3-13. AM-2060(*)/GRC, Plug-In Assembly,
Removal and Replacement
The plug-in assembly (fig. 3-11) is removed for
performing repairs on it (fig. 3-13 and 3-14),
and to gain access to parts under it (fig. 3-12).
Before proceeding, remove all cable connections
to the AM–2060(*)/GRC and remove the access
plate from the top of the equipment (fig.3-10).
a. Plug-In Assembly Removal and Replacement.
(1) Removal.
(a) Remove the four captive screws that
hold the plug-in assembly to the chassis (fig.
3-11).
(b) Grasp the plug-in assembly and pull
the assembly straight up and out of the equipment.
(2) Replacement.
(a) Insert the plug-in assembly so that
the plug on the bottom of the assembly mates
with the receptacle J1 on the bottom of the
AM-2060-(*)/GRC (fig. 3-12).
(b) Tighten the four captive screws on
the plug-in assembly (fig. 3-11). Make sure that
the plug-in assembly is not loose.
(c) Replace the access plate on top of the
AM-2060(*)/GRC.
b. Plug-In Assembly Printed Circuit Board,
Removal and Replacement. Use the following
procedures to remove and replace the printed circuit board of the plug-in assembly.
(1) Removal.
(a) Remove the plug-in assembly (a(1)
above).
(b) Unsolder the wires attached to test
points E1 through E17 (fig. 3-9) on the top of
the plug-in assembly. Tag each wire with the
identification of the terminal from which it was
removed.
(c) Remove the screws, nuts, and spacers
that secure the printed circuit board to the plugin assembly.
(2) Replacement (fig. 3-15).
(a) Insert a screw and washer through
each of the four mounting holes of the printed
circuit board.
(b) Place a spacer over each of the four
screws.
(c) Align the mounting holes of the plugin assembly with the screws in the printed circuit
board and insert the screws through the mounting holes.
(d) Place a washer and nut on each of the
four screws and tighten the nut securely.
(e) Solder the wires to test points E1
through E17 (fig. 3-9). Check each wire tag to
insure the correct replacement.
(f) Replace the plug-in assembly in the
AM–2060(*)/GRC (a(2) above).
3-14. AM-2060(*)/GRC, Loudspeaker LS1
Removal and Replacement
The loudspeaker is removed from the front panel
for testing and replacement, or to gain acc'ess to
the area behind it. Before proceeding, remove all
cable connections.
a. Removal.
(1) Remove the four mounting screws that
attach the loudspeaker cover with the loudof
the
speaker
attached to the front
AM–2060(*)/GRC. Place the nylon strap attached to the SET POWER connector dust cap
clear of the loudspeaker area.
(2) Grasp the front of the loudspeaker
cover and pull the loudspeaker cover from the
loudspeaker by holding LS1 firmly and snapping
the cover off.
WARNING
When soldering and unsoldering the voice
coil leads, be careful to prevent the glass portion of the terminals from cracking due to
excessive heat. Grasp the terminal lead with
a pair of pliers, between the glass bead and
the eye of the terminals, before applying
heat.
(3) Unsolder the leads that connect the voice
coil of LS1 to the feedthrough terminals at the
3-13
TM 11-5820-498-35
Figure 3-10. AM-2060( * )/GRC, access plate and gasket.
(4) Replace the Mounting screws and nylon
strap.
c. Testing Voice Coil Polarity. When a 4.5
±1.5 volt dc potential is connected to the voice
coil terminals, with the positive polarity applied
to the terminal next to the red mark, the voice
coil shall move in a direction away from the mag
net.
3–15.
Figure 3-9. AM-2060 ( * )/GRC, plug-in assembly, test
points with voltage and resistance indications.
voice coil terminals. Tag the leads (VC1 or VC2)
to insure correct replacement. Remove LS1. See c
below for testing the polarity of the loudspeaker
magnet.
b. Replacement.
(1) Place the loudspeaker cover on a new
LS1 by holding LS1 firmly and snapping the cover
i n place. Check to insurc that the mounting holes
in the cover align with the mounting holes in
LS1.
(2) Solder the leads that come from the
feedthrough terminals VC1 and VC2.
(3) Place LS1 in the loudspeaker cavity.
Check to insure that the mounting holes in the
loudspeaker cover and LS1 align with the mounting holes in the front of the AM- 2060(*) /GRC.
3-14
AM-2060(*)/GRC, ANT. FREQ.
CONTROL Switch S2, Removal and
Replacement
(fig. 3-12 and 3-16)
a. Removal.
( 1 ) Remove the access plate from the top of
the AM- 2060(*)/(GRC.
(2) Set the ANT. FREQ. CONTROL to
30–33 position.
(3) Remove the knob retaining screw (A, fig.
3-16). Remove the switch knob from the switch
shaft.
(4) Remove the nut that secures the switch
to the front panel.
(5) Slide switch S2 back into the compartment. Do not exert too much force or push the
switch back too far; the leads may break.
(6) Hold the replacement switch in th
exact position as the original switch, remove th
connecting wires and capacitors C1 through C7
(fig. 3-12) from the original switch, one at a
time, and connect them to the corresponding contact on the replacement switch.
b. Replacement.
(1) Replace the switch shaft through the
opening in the f ront panel.
TM 11-5820-498-35
Figure 3-11. AM-2060(*)IGRC, top view with plug-in assembly in place.
Figure 3–12. AM–2060(*)/GRC, top view with plug-in assembly removed.
3-15
TM 11–5820-498-35
Figure 3-13. AM-2060(*)/GRC, plug-in assembly front view, parts location.
(2) Rotate the switch shaft so that the knob
will be in the proper position when it is replaced
on the shaft.
(3) Replace and tighten the nut; hold the
switch in the proper position until the nut is
tightened.
(4) Replace the knob on the switch shaft,
and secure it i n place with the retaining screw.
Figure 3-14. AM-2060(*)/GRC, plug-in assembly,
rear view, parts location.
3-16
3–16. Rewiring POWER INPUT Connector J3
AM-2060(*)/GRC’S on Orders No. 15108-PP-62
and 5175-PP-64 were wired incorrectly at
POWER INPUT connector J3 (note 10, fig. 4–9).
Tests to determine the faulty equipment are
given in a below ; rewiring instructions are given
in b below. If the equipment is wired incorrectly
a closed circuit to the dc vehicular dc power ex
ists even when the AM–2060(*)/GRC PWR
switch is set to OFF.
a. Tests. When the AM–2060(*)/GRC PWR
switch is set to OFF, the associated receivertransmitter should not be able to be turned on.
However, when the AM-2060(*)/GRC is wired
TM 11-5820-498-35
Figure 3-15. AM-2060(*)/GRC, plug-in assembly, exploded view.
incorrectly at J3, the receiver-transmitter can be
turned on even when the PWR switch is set to
OFF. If any of the following tests indicates the
wiring is incorrect, proceed to the rewiring procedures in b below.
(1) Method No. 1. Set the AM-2060(*)/
GRC PWR switch to OFF and connect an ohmmeter between pins A and B of POWER
INPUT connector J3 (D, fig. 3-4). If the ohmmeter indicates continuity, J3 wiring is incorrect.
(2) M e t h o d N o . C o n n e c t t h e A M 2060(*)/GRC to a dc power source (para
3-4). Use the CX–4655/GRC to connect a receiver-transmitter to the AM–2060(*)/GRC. Set
the AM–2060(*)/GRC PWR switch to OFF.
(a) Set the receiver-transmitter function
3-17
TM 11-5820-498-35
switch to LITE. If the dial map lights, J3 wiring is
incorrect.
(b) Set tile receiver-transmitter function
switch to ON. If a rushing noise is heard in a
handset connected to the receiver-transmitter, J3
wiring is incorrect.
b. Rewiring INPUT POWER Connector J3. If
any of the tests performed in a above indicates that
J3 wiring is incorrect, rewire the leads at J3 to
conform to the circuit shown in figure 4-9. The
incorrect wiring at J3 is shown in figure 4-9, note
10. To facilitate the work, remove the plug-in
assembly (para 3- 13). Perform the operational test
in a above when the rewiring is completed.
CAUTION
Make sure all changed wires are properly
taped with electrical insulation tape.
c. Installation of Zener Diode CR1 in place of
Capacitor C8. If capacitor C8 is defective it will be
replaced by diode CR 1. Remove capacitor C8 and
install CR1 in its place (fig. 3-16.1).
Figure 3-16. AM-2060(*), front panel, parts location.
3-18
Change 3
TM 11-5820-498-35
Figure 3-16.1. Installation of diode CR1.
Change
3-18.1
TM 11-5820-498-35
Section IV. OA-3633(*)/GRC, TESTING PROCEDURES
3-17. General
Before a repaired AM-2060(*)/GRC is returned to
the using organization, or to. stock, it must be
tested for acceptable performance. The AM2060(*)/GRC performance checks include physical
tests (para 3-18), and testing the continuity of
circuits (para 3-19), dc output voltages (para 3-20),
and the audiofrequency amplifier circuits (para
3-18.2
Change 3
3-21 and 3-22). The CX-4655/GRC test procedures
are given in paragraph 3-23.
3-18. Physical Tests and Inspection
a. Test Equipment and Material. None.
b. Test Connection and Conditions. Remove the
access plate from the top of the AM-2060(*)/GRC.
TM 11-5820-498-35
3-19. Circuit Continuity and Resistance
The following tests check the circuits that are
not involved in the tests in paragraphs 3-20, 3-21,
and 3-22.
a. Test Equipment and Materiel. Multimeter
ME-26(*)/U, used as an ohmmeter.
b. Test Connections and Conditions. Connect
the ME-26(*)/U to the indicated pins on the receptacles given in c below.
c. Procedure. In the following procedures
“J3-C”, “J2-A”, etc., indicate the receptacle and
the pins on the receptacle: receptacle J3, pin C;
receptacle J2, pin A, etc.
NOTE
SET POWER receptacle J2 is on the front
panel (fig. 3-17) and POWER INPUT receptacle J3 is on the rear panel (fig. 3-4).
3-19
Change 1
TM 11-5820-498-35
3-20
TM 11-5820-498-35
3-20. Output Voltages Tests
a. Test Equipment and Materials.
(1) Multimeter ME-26(*)/U.
(2) Mounting MT-1029/VRC.
(3) Power Supply PP-2953(*)/U, or equal.
(4) Cable Assembly, Power, Electrical CX-4720/VRC.
(5) Transmit and receive dummy load assemblies.
b. Test Connections and Conditions. Connect the equipment as shown in figure 3-17. Turn the equipmen on, and allow it to warm up for 5 minutes before proceeding.
c. Procedure.
Change 1
3-21
TM 11-5820-4984-35
Control settings
Step
No.
Test equipment
Equipment under
test
Test proccedure
Performance
standard
RANGE switch: 100V
(zero meter)
b. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
30-33 MCS. Connect the
ME-26(*)/U DC probe
to pins A, D, and N of
the receptacle.
c. Set the AM–2060(*)/GRC
ANT. FREQ. CONTROL
to 33-37 MCS. Connect
the ME-26(*)/U DC
probe to pins A and E
of the receptacle.
d. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 37-42 MCS. Connect
the ME-26(*)/U DC
probe to pins A and F
of the receptacle.
e. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 42-47.5 MCS. Connect
the ME-26(*)/U DC
probe to pins A and H
of the receptacle.
f. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 47.5–53 MCS. Connect
the ME-26(*) /U probe
to pins A and J of the
receptacle.
g. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 53-56 MCS. Connect
the ME-26(*)/U DC
probe to pins B and D
of the receptacle.
h. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 56-60 MCS. Connect
the ME-26(*)/U DC
probe to pins B and E of
the receptacle.
i. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 60-65. Connect the
ME-26(*)/U DC probe
to pins B and F of the
receptacle.
j. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 65-70.5 MCS. Connect
the ME–26(*)/U DC
probe to pins B and H of
the receptacle.
k. Set the AM-2060(*)/GRC
ANT. FREQ. CONTROL
to 70.5–76 MCS. Connect
the ME-26(*)/U DC
probe to pins B and J
of the receptacle.
3-22
b. 25.5 volts on pins A, D, and
N.
c. 25.5 volts on pins A and E.
d. 25.5 volts on pins A and F.
e. 25.5 volts on pins A and H.
f. 25.5 volts on pins A and J.
g. 26.5 volts on pins B and D.
h. 25.5 volts on pins B and E.
i. 25.5 volts on pins B and F.
j. 25.5 volts on pins B and H.
k. 25.5 volts on pins B and J.
TM 11-5820-498-35
3-21. Audio Amplifier Gain and Frequency Response Tests
a. Test Equipment and Materials.
(1) Generator, Signal AN/URM--127.
(7) Resistor, carbon: 130 ohms
(2) Voltmeter, Electronic ME-30(*)/U.
±10%, 5 watt 8.
(3) Mounting MT-1029/VRC.
(4) Power Supply PP-2953(*)/U, or equal.
(6) Cable Assembly, Power, Electrical CX-4720/VRC.
(6) Receive dummy load assembly (para 3-3e, fig. 3-1).
b. Test Connection and Conditions. Remove the access plate from the top of the AM-2060(*)/GRC and
connect the equipment as shown in figure 3-18. Turn on the equipment and allow it to warm up for 5
minutes before preceding.
C.
Procedure.
Change 2
3-23
3-24 Change 2
Change 2
3-25
TM 11-5820-498-35
3-22. Audio Amplifier Distortion Test
a. Test Equipment and Materials.
(1) Generator, Signal AN/URM-127.
(6) Voltmeter, Electronic
(2) Spectrum Analyzer TS-723A/U.
ME-30(*)/U.
(3) Mounting MT-1029/VRC.
(7) Resistor, carbon: 130
ohms, ±10%, 5 watts.
(4) Power Supply PP-2953(*)/U, or equal.
(5) Receive dummy load assembly (para 3-3e, fig. 3-1).
b. Test Connection and Conditions. Connect the equipment as shown in A, figure 3–19. Turn on the
equipment and allow it to warm up 5 minutes before proceeding,
c. Procedure.
3-23. CX-4655/GRC, Test Procedure
a. Test Equipment and Materials. Use Multimeter ME-26(*)/U as an ohmmeter.
b. Test Connections and Conditions. Use the
ME-26(*)/U as instructed in c below.
c. Procedure (fig. 3–5).
(1) Continuity test. Use the ME-26(*)/U to
test the continuity (O ohm) between each pin of
connector P2 with the corresponding pin on
connector P5, except that between pins F, L, and
R there is no continuity (infinite resistance).
3-26
Change 2
(2) Short circuit test. No two pins on P2
and P5 should indicate a short circuit (O ohm)
when the ME–26(*)/U is connected between the
pins on the connector.
TM 11-5820-498-35
3-23.1. Circuit Breaker Test of PWR Switch
a. Teat Equipment and Materiels.
(1) Mounting MT-1029/VRC.
(2) Power Supply PP-1104/G.
(3) Cable Assembly, Power, Electrical CX4020/VRC.
b. Test Connection and Conditions. Turn off the
PP-1104/G and set its OUTPUT control fully counterclockwise (minimum output). Connect the PP1104/G through the CX-4720/VRC to the MT1029/VRC and AM-2060(*)/GRC (fig. 3-19). Remove
the access plate from the top of the AM-2060(*)/GRC
and connect a jumper between test point E5 (fig. 3-9)
and the chassis.
c. Procedure.
(1) Adjust the PP-1104/G OUTPUT control clockwise until the D.C. AMPERE meter indicates 4 amperes. The AM-2060(*)/GRC PWR circuit breaker
shall not have tripped.
(2) Continue to rotate the OUTPUT control
clockwise until the D.C. AMPERE meter indicates 6
amperes. The AM-2060(*)/GRC PWR circuit breaker
shall have tripped before 6 ampere indication is
reached.
NOTE
The magnetic circuit breaker required up
to 1 ampere beyond its Specification
requirement because of its proximity to
the loudspeaker magnet.
(3) Turn off the equipment and remove the
jumper connection to teat point E5.
3-24. Summary of Test Data
Personnel may find it convenient to arrange a
checklist of the test performance standards given in
paragraphs 3-19 through 3-32.1 similar to the one
given below.
Change 2
3-27
TM 11-5820-498-35
3-28 Change 2
TM 11-5820-498-35
CHAPTER 4
DEPOT OVERHAUL STANDARDS
4-1. Applicability of Depot Overhaul
Standards
The tests on repaired equipment are designed to measure the performance capability of the equipment.
Equipment that is returned to stock should meet the
standards given in the tests.
NOTE
The depot overhaul test procedures (DOS)
should not be used to test the performance
of new equipment; that is, equipment that
has not been repaired or rebuilt. Such
equipment should be tested for conformance
with the electrical and operational tests
cited in the Military Specification under
which the equipment was manufactured including all waivers and/or changes to the
specification that were imposed upon or
granted to the particular manufacturer of
the equipment. For such information, address correspondence to: Commander, US
Army Communications-Electronics Command, ATTN:DRSEL-ME-MQ, Fort Monmouth, NJ 07703.
Following are production specifications applicable to the radio equipment covered in
this manual:
1. Amplifier-Power Supply Group
OA-3633(*)/GRC: Military Specification
MIL-A-55147B(EL).
2. Antenna AS-1729/VRC: Military Specification MIL-A-55288B(EL).
3. Radio Set AN/PRC-25, Including
Radio
Receiver-Transmitter,
RT-505/PRC-25: Military Specification
MIL-R-55137C(EL).
4. Radio Set AN/PRC-77, Including
Radio
Receiver-Transmitter,
RT-841/PRC-77: Military Specification,
MIL-R-55499B(EL).
4-2. Applicable References
a. Repair Standards. Applicable procedures of depots performing tests and general standards for repaired electronic equipment given in TB SIG 355-1, TB
SIG 355-2, and TB SIG 355-3 form a part of the re
quirements for testing the components of the radio sets
covered by this manual.
b. Modification Work Orders. Perform all modification work orders (MWO’s) applicable to the equipment before making tests specified. DA Pam 310-7 lists
current MWO’s.
4-3. Depot Overhaul Standards
Procedures
Refer to the following publications for the depot overhaul standards for the indicated equipment which are
part of Radio Sets AN/VRC-53, AN/VRC-64, AN/
GRC-125, and AN/GRC-160.
Publication
Component
Amplifier-Power Supply Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paragraphs 3-18 through
OA-3633(*)/GRC.
3-24 of this publication.
Radio Set AN/PRC-25, including . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5820-398-35.
Receiver-Transmitter, Radio
RT-505/PRC-25.
Radio Set AN/PRC-77 including . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5820-667-35.
Receiver-Transmitter, Radio
RT-841/PRC-77.
Antenna AS-1729/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TM 11-5985-262-15.
Change 4
4-1/(4-2 blank)
TM 11-5820-498-35
APPENDIX A
REFERENCES
CTA 50-970
DA Pam 310-4
SB 11-131
TB SIG 355-1
TB SIG 355-2
TB SIG 355-3
TM 11-5820-398-12
TM 11-5820-398-35
TM 11-5820-398-20P
TM 11-5820-398-34P
TM 11-5820-401-10-1
TM
11-5820-401-102
TM
11-5820-401-12
TM 11-5820-401-20P
TM 11-5820-401-30-4
Expendable Items (Except: Medical, Class V, Repair Parts and Heraldic Items).
Index of Technical Publications.
Vehicular Radio Sets and Authorized Installations.
Depot Inspection Standard for Repaired Signal Equipment.
Depot Inspection Standard for Refinishing Repaired Signal Equipment.
Depot Inspection Standard for Moisture and Fungus Resistance Treatment.
Operator’s and organizational maintenance manual including repair parts and special
tools lists: Radio set AN/PRC-25 (NSN 5820-00-857-0759) (including receiver-transmitter, radio, RT-505/PRC-25) (NSN 5820-00-857-0934) (Reprinted w/basic incl ch 1-5).
Field and depot maintenance manual: Radio set AN/PRC-25.
Organizational maintenance repair parts and special tools lists: Radio set AN/PRC-25
(NSN 5820-00-857-0759).
Direct support and general support maintenance repair parts and special tools lists
(including depot maintenance repair parts and special tools lists: Radio set AN/PRC-25
(NSN 5820-00-857-0759).
Operator’s manual: Radio sets AN/VRC-12 (NSN 5820-00-223-7412), AN/VRC-46
(NSN 5820-00-223-7433), AN/VRC-47 (NSN 5820-00-223-7434), AN/VRC-48 (NSN
5820-00-223-7435), and AN/VRC-49 (NSN 5820-00-223-7437) (used without an
intercom system).
Operator’s manual: Radio sets AN/VRC-12 (NSN 5820-00-223-7412), AN/VRC-46 (NSN
5820-00-223-7433), AN/VRC-47 (NSN 5820-00-223-7434), AN/VRC-48
(NSN 5820-00-223-7435), and AN/VRC-49 (NSN 5820-00-223-7437) (used with an
intercom system).
Operator’s and organizational manual (including repair parts and special tools lists):
Radio sets AN/VRC-12 (NSN 5820-00-223-7412), NSN 5820-00-223-7415), AN/VRC-44
(NSN 5820-00-223-7417), AN/VRC-45 (NSN 5820-00-223-7418), AN/VRC-46 (NSN
5820-00-223-7433), AN/VRC-47 (NSN 5820-00-223-7434),
AN/VRG-48 (NSN 5820-00-223-7437), AN/VRC-49 (NSN 5820-00-223-7437),
AN/VRC-54 (NSN 5820-00-223-7567), and AN/VRC-55 (NSN
5820-00-402-2265); Mounts, MT-1029/VRC
(NSN 5820-00-893-1323) and MT-1898/VRC (NSN 5820-00-893-1324); Antenna,
AT-912/VRC (NSN 5820-00-897-6357); Control frequency selector C-2742/VRC
(NSN 5820-00-892-3343), and Control, radio set C-2299/VRC (NSN 5820-00-892-3340)
(Reprinted w/basic incl ch 1-3).
Organizational maintenance repair parts and special tools lists: Radio sets AN/VRC-12
(NSN 5820-00-223-7412), AN/VRC-43 (NSN 5820-00-223-7415), AN/VRC-44
(NSN 5820-00-233-7417), AN/VRC-45 (NSN 5820-00-223-7418), AN/VRC-46 (NSN
5820-00-223-7433), AN/VRC-47 (NSN 5820-00-223-7434), AN/VRC-48 (NSN 5820-00223-7435), AN/VRC-49 (NSN 5820-00-223-7437), AN/VRC-54 (NSN 5820-00-2237567), and AN/VRC-55 (NSN 5820-00-402-2265); Receiver-transmitter, radio, RT-246/
VRC and RT-246A/VRC (NSN 5820-00-892-0623), RT-524/VRC and RT-524A/VRC
(NSN 5820-00-892-0622); Receivers, radio R-442/VRC and R-442A/VRC (NSN 582000-892-0624); Mounts, MT-1029/VRC (NSN 5820-00-892-1323) and MT-1898/VRC
(NSN 5820-00-893-1324); Control, frequency selector, C-2742/VRC (NSN 5820-00-8923343), and Control, radio set, C-2299/VRC (NSN 5820-00-892-3340) (Navelex 0967LP-432-3160).
Direct support maintenance manual (including repair parts and special tools lists):
Amplifier, radio frequency AM-1780/VRC (NSN 5820-00-592-3342) (Navelex
0967-LP-432-3080) (Reprinted w/basic incl ch 1).
Change 4 A-1
TM 11-5820-498-35
TM 11-5820-401-34-2
TM 11-5820-401-34-3
TM 11-5820-401-34P-2-1
TM 11-5820-401-34P-2-2
TM 11-5820-401-35-1
TM 11-5820-401-35-6
TM 11-5820-401-35-7
TM 11-5820-401-35-8
TM 11-5820-401-35-9
TM 11-5820-497-20P
TM 11-5820-497-34P
TM 11-5820-498-12
TM 11-5820-498-20P
A-2
Change 4
Direct support and general support maintenance manual: Radio sets, AN/VRC-12
(NSN 5820-00-223-7412), AN/VRC-43 (NSN 5820-00-223-7415), AN/VRC-44 (NSN
5820-00-223-7418), AN/VRC-46 (NSN 5820-00-223-7433), AN/VRC-47 (NSN
5820-00-223-7434), AN/VRC-48 (NSN 5820-00-223-7435), and AN/VRC-49 (NSN
5820-00-223-7437), and Receiver-transmitters, radio, RT-246/VRC and
RT-246A/VRC (NSN 5820-00-892-0623), RT-524/VRC and RT-524A/VRC (NSN
5820-00-892-0622) (Navelex 0967-LP-432-3030) (Reprinted w/basic incl ch 1).
Direct support and general support maintenance manual: Radio sets, AN/VRC-12
(NSN 5820-00-23-7412), AN/VRC-43 (NSN 5820-00-223-7415), AN/VRC-44 (NSN
5820-00-223-7418), AN/VRC-46 (NSN 5820-00-223-7433), AN/VRC-47 (NSN
5820-00-223-7434), AN/VRC-48 (NSN 5820-00-223-7435), and AN/VRC-49 (NSN
5820-00-223-7437); and Receivers, radio R-442/VRC and R-442A/VRC (NSN
5820-00-892-0624) (Navelex 0967-LP-432-3060).
Direct support and general support maintenance repair parts and special tools lists
(including depot maintenance repair parts and special tools lists): Receivertransmitters, radio RT-246/VRC and RT-246A/VRC (NSN 5820-00-892-0623).
Direct support and general support maintenance repair parts and special tools lists
(including depot maintenance repair parts and special tools lists): Receiver-transmitters, radio RT-524/VRC and RT-524A/VRC (NSN 5820-00-892-0622).
R-442/VRC and R-442A/VRC (NSN 5820-00-892-0624).
Direct support, general support and depot maintenance manual (including repair
parts and special tools lists): Control frequency selector C-2742/VRC, and
Control, radio set C-2299/VRC (Navelex 0967-LP-432-3020) (Reprinted w/basic
incl ch 1).
Direct support, general support and depot maintenance manual (including repair
parts and special tools lists): Control, intercommunication set, C-2299/VRC (NSN
5820-00-892-3337) (Navelex 0967-LP-432-3100) (Reprinted w/basic incl ch 1).
Direct support, general support and depot maintenance manual (including repair
parts and special tools lists): Control, Intercommunication set, C-2297/VRC
(Navelex 0967-LP-432-3110) (Reprinted w/basic incl ch 1).
Direct support, general support and depot maintenance manual (including repair
parts and special tools lists): Control, intercommunication set, C-2298/VRC (NSN
5820-00-892-3339) (Navelex 0967-LP-432-3120) (Reprinted w/basic incl ch 1).
Direct support, general support and depot maintenance manual (including repair
parts and special tools lists): Mountings, MT-1029/VRC (NSN 5820-00-893-1323)
and MT-1898/VRC (NSN 5820-00-893-1324) (Navelex 0967-LP-432-3131) (Reprinted
w/basic incl ch 1).
Organizational maintenance repair parts and special tools lists for ReceiverTransmitter, Radio RT-505/PRC-25 (NSN 5820-00-857-0934).
Direct support and general support maintenance repair parts and special tools lists
(including depot maintenance repair parts and special tools lists): Receivertransmitter, radio, RT-505/PRC-25 (NSN 5820-00-857-0934).
Operator’s and organizational maintenance manual: Radio sets AN/VRC-53 (NSN
5820-00-223-7467), AN/VRC-64 (NSN 5820-00-223-7475), AN/GRC-125 (NSN
5820-00-223-7411), and AN/GRC-160 (NSN 5820-00-223-7473), and Amplifier power
supply group OA-3633/GRC.
Organizational maintenance repair parts and special tools lists: Radio sets, AN/
VRC-53, AN/VRC-64, AN/GRC-125, and AN/GRC-160, and Amplifier power
supply groups, OA-3633/GRC and OA-3633A/GRC (parts list for OA-3633GRC
and OA-3633A/GRC, NSN 5820-00-973-3383, only).
TM 11-5820-498-35
TM 11-5820-498-34P
TM 11-5820-667-12
TM 11-5820-667-20P
TM 11-5820-667-34P
TM 11-5820-667-35
TM 11-5983-262-15
TM 11-5950-212-15
TM 11-5965-257-15
TM 11-5965-262-13
TM 11-5965-280-15
TM 11-5965-282-15
TM 11-6625-200-15
TM 11-6625-255-14
TM 11-6625-320-12
TM 11-6625-514-12
TM 11-6625-683-15
TM 38-750
Direct support and general support maintenance repair parts and special tools lists
(including depot maintenance repair parts and special tools lists): Radio sets, AN/
VRC-53, AN/VRC-64, AN/GRC-125, and AN/GRC-160, and Amplifier power
supply groups OA-3633/GRC and OA-3633A/GRC (parts list for OA-3633/GRC and
OA-3633A/GRC, NSN 5820-00-973-3383, only).
Operator’s and organizational maintenance manual including repair parts list: Radio
set AN/PRC-77 (NSN 5820-00-930-3724) (Including Receiver-transmitter, radio,
RT-841/PRC-77) (NSN 5820-00-930-3725) (Reprinted w/basic incl ch 1-7).
Organizational maintenance repair parts and special tools lists: Radio set,
AN/PRC-77 (NSN 5820-00-930-3724).
Direct support and general support maintenance repair parts and special tools lists
(including depot maintenance repair parts and special tools lists): Radio set, AN/
PRC-77 (NSN 5820-00-930-3724).
Direct support, general support and depot maintenance manual: Radio set
AN/PRC-77 (Reprinted w/basic incl ch 1).
Operator’s organizational, direct support, general support and depot maintenance
manual including repair parts and special tools lists: Antenna, AS-1729/VRC
(NSN 5820-00-985-9024) (Reprinted w/basic incl ch 1-6).
Operator’s, organizational, direct support, general support and depot maintenance
manual including repair parts and special tools lists: Variable power transformer
TF-523/U (NSN 5950-00-926-0742).
Organizational, direct support, general support and depot maintenance manual
including repair parts and special tools lists: Handsets, H-138/U and H-138A/U
(FSN 5965-892-0972).
Organizational and direct support maintenance manual including repair parts and special
tools lists: Headset-microphone H-161/U and H-161A/U (FSN 5965-082-0437 and
5965-824-4871 ) (Reprinted w/basic incl ch 1-2).
Operator’s, organizational, direct support, general support and depot maintenance
manual including repair parts and special tools lists: Handset H-189/GR (NSN
5965-00-069-8886).
Operator’s, organizational, direct support, general support and depot maintenance.
manual including repair parts and special tools lists: Headset-microphone kit
MK-1039/G (Reprinted w/basic incl ch 1-2).
Operator’s, organizational, direct support, general support and depot maintenance
manual: Multimeters ME-26A/U (NSN 6625-00-360-2493), ME-26B/U, ME-26C/U
(NSN 6625-00-646-9409), ME-26 D/U (NSN 6625-00-913-9781).
Operator’s, organizational, direct support, and general support maintenance manual:
Spectrum analyzers TS-723A/U, TS-723B/U, TS-723C/U, and TS-723D/U (NSN
6625-00-668-9418).
Operator’s and organizational maintenance manual: Voltmeter, meter ME-30A/U and
Voltmeters, Electronic ME-30B/U, ME-30C/U, and ME-30E/U.
Operator’s and organizational maintenance manual: Test sets, electronic circuit plug-in
units AN/GRM-55, AN/GRM-55A, AN/GRM-55B, and AN/GRM-55C.
Operator’s, organizational, direct support, general support and depot maintenance
manual: Signal generator AN/URM-127 (NSN 6625-00-783-5965).
The Army Maintenance Management System (TAMMS).
Change 4 A-3
TM 11-5820-498-35
Figure 4-1. Color code markings for MIL-STD resistorss.
TM 11-5820-498-35
By Order of the Secretary of the Army:
Official:
KENNETH G. WICKHAM,
Major General, United States Army,
The Adjutant General.
W. C. WESTMORELAND,
General, United States Army,
Chief of Staff.
Distribution:
To be distributed in accordance with DA Form 12-51, Direct and General Support requirements
for following equipments: AN/GRC-125, AN/VRC-53 and OA-3633/GRC.
*U.S. GOVERNMENT PRINTING OFFICE: 1994-342-421/81111
PIN: 030695-000
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