Figure 5-8. Test Setup for Radio Set Control C-7999/GRC-171

TO 31R2-2GRC171-2

TM 11-5820-815-14

NAVELEX 0967-LP-544-5010

a. Connect distortion analyzer and 600-ohm load

5-9.

VOLTAGE REQUIREMENTS AND SOURCES.

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

5-10. Radio Set AN/GRC-171 and test equipment

require 120-V ac, 60-Hz, single-phase power for

b. Set the rf signal generator for rf output level of 2

operation.

to 2.5 V at 300.000 MHz, 30 percent modulation at 1

kHz.

5-11.

ALIGNMENT.

c. Set the RT-980/GRC-171 REMOTE/LOCAL

5-12. No alignment is required at the organizational/

switch to LOCAL, PTT/CARRIER TEST switch to PTT,

intermediate maintenance level. Alignment is performed

SQUELCH switch to ON, and frequency switches to

at the module level and is covered in section H.

300.000 MHz.

d. Set distortion analyzer FUNCTION control to

5-13.

ADJUSTMENT.

VOLTMETER and observe RT-980/GRC-171 main audio

5-14. RECEIVE AUDIO. To adjust the receive audio

output voltage.

level, connect equipment as shown in figure 5-2 and

proceed as follows:

e. Adjust SQUELCH level control (behind front

panel access door) counterclockwise from maximum

a. Connect distortion analyzer and 600-ohm load

until an audio output signal is obtained (main audio

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

output voltage will be 7.25 to 9.0 V rms).

b. Set the rf signal generator for rf output level of 3

5-16. MODULATION PERCENTAGE. To adjust the

V at 225.000 MHz, 30 percent modulation at 1 kHz.

transmitter modulation percentage, connect equipment

as shown in figure 5-5 for modulation check and proceed

c. Set the RT-980/GRC-171 REMOTE/LOCAL

as follows:

switch to LOCAL, PTT/CARRIER TEST switch to PTT,

SQUELCH switch to OFF, and frequency switches to

a. Set the RT-980/GRC-171 REMOTE/LOCAL

225.000 MHz.

switch to LOCAL, PTT/CARRIER TEST switch to

CARRIER TEST, SQUELCH switch to OFF, and fre-

d. Set distortion analyzer FUNCTION control to

quency switches to 300.000 MHz.

VOLTMETER and observe RT-980/GRC-171 main audio

output voltage.

b. Set audio oscillator output for 2.45 V rms (+10

dB mW) at 1000-Hz input to RT-980/GRC-171 as

e. Adjust RCV AUDIO level control (behind front

observed on the digital multimeter.

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

across the 600-ohm load.

c. Set rf signal generator to 298.000 MHz and while

observing oscilloscope display, adjust rf signal generator

5-15. SQUELCH. To adjust the squelch level, connect

output to obtain the RT-980/GRC-171 modu-lation

equipment as shown in figure 5-2 and proceed as

envelope.

follows.

5-28