SIDETONE

TO 31R2-2GRC171-2

TM 11-5820-815-14

NAVELEX 0967-LP-544-5010

d. Measure and determine modulation percentage

5-22. REMOVAL OF MODULE. To remove d/a servo

using the oscilloscope display and the following formula:

amplifier module from chassis, refer to figure 5-10 and

-E

proceed as follows:

MAX MIN x 100%

M =

MAX MIN

a. Remove top cover.

e. Adjust % MOD control (behind front panel

b. Loosen six captive screws around periphery of

access door) to obtain 85 to 95 percent modulation.

module retainer bracket and remove bracket.

NOTE

c. Disconnect transmit rf cable A10A2P1 from

A2A6J1.

Ensure that over modulation does not occur.

A minimum rf level of zero corresponds

d. Remove module by carefully sliding module to

to over modulation of the RT-980/GRC-171.

the rear, disengaging A1P1 from A10A2J10, and lifting

module from chassis.

5-17. SIDETONE. To adjust transmitter sidetone,

5-23. REPLACEMENT OF MODULE. Replace mod-

connect equipment as shown in figure 5-6 for transmitter

ule in the reverse order of its removal.

power output and proceed as follows:

CAUTION

a. Connect audio oscillator and 600-ohm load

across the RT-980/GRC-171 main audio input.

Ensure proper module-to-chassis plug and

pin alignment is achieved before sliding

b. Connect distortion analyzer and 600-ohm load

module into position. Do not exert abnormal

across the RT-980/GRC-171 main audio output and set

force to seat module.

distortion analyzer FUNCTION control to VOLTMETER.

c. Set audio oscillator output for 2.45 V rms at

5-24.

FREQUENCY SYNTHESIZER MODULE A2.

1000-Hz input to RT-980/GRC-171 as observed on

digital multimeter.

5-25. REMOVAL OF MODULE. To remove frequency

synthesizer module from chassis, refer to figure 5-10 and

d. Set RT-980/GRC-171 REMOTE/LOCAL switch

proceed as follows:

to LOCAL, PTT/CARRIER TEST switch to CARRIER

TEST, SQUELCH switch to OFF, and frequency

a. Remove top cover.

switches to 300.000 MHz.

b. Loosen six captive screws around periphery of

e. Adjust SIDETONE level control (behind front

module retainer bracket and remove bracket.

panel access door) to obtain 7.75 V rms (100 mW) audio

output as observed on distortion analyzer VOLTMETER.

c. Disconnect transmit rf cable A10A2P1 from

A2A6J1 and the receive injection cable A2A6P2 from

5-18. TROUBLESHOOTING.

A3J1.

5-19. Troubleshooting procedures are presented in

flow-chart form.

Figure 5-9 is the troubleshooting

d. Remove module by carefully sliding module to

procedures for Radio Set AN/GRC-171.

the rear, disengaging A2P1 from AlOA2Jll, and lifting

troubleshooting Radio Set AN/GRC-171, use the block

module from chassis.

diagrams and schematic diagrams of chapters 4 and 6

with the troubleshooting procedures of figure 5-9 for

5-26. REPLACEMENT OF MODULE. Replace mod-

trouble analysis and location.

ule in the reverse order of its removal.

5-20.

REMOVAL/REPLACEMENT.

CAUTION

Ensure proper module-to-chassis plug and

pin alignment is achieved before sliding mod-

Turn power off before removal or replace-

ule into position. Do not exert abnormal force

ment of any module.

to seat module.

5-21.

D/A SERVO AMPLIFIER MODULE A1.

5-29