Table 5-3. Radio Receiver-Transmitter RT-980/GRC-171 Performance Tests (Sheet 11 of 17)

TO 31R2-2GRC171-2

TM 11-5820-815-14

NAVELEX 0967-LP-544-5010

CONTROL SETTINGS

OPERATION OF TEST

AND OPERATION

PERFORMANCE

STEP

EQUIPMENT

POINT OF TEST

OF EQUIPMENT

STANDARD

TRANSMITTER NARROW-BAND MODULATION

Connect equipment as

XCVR

Set REMOTE/LOCAL

shown in figure 5-6.

(A10W3J2)

switch to LOCAL,

Set audio oscillator

PTT/CARRIER TEST

for 2.45 V rms (+10

switch to CARRIER

dB mW) at 1000-Hz

TEST, SQUELCH

input to RT-980/

switch to OFF, and

GRC-171 as observed

frequency switches

on digital multimeter.

to 300.000 MHz.

Set rf signal genera-

tor to 298.000 MHz.

While observing os-

cilloscope display,

adjust rf signal

generator output level

to obtain RT-980/

GRC-171 modulation

envelope.

Measure and determine

Adjust % MOD

85 to 95%.

the modulation per-

adjustment if

centage using the oscil-

necessary to ob-

loscope display and the

tain required

following formula:

percent of

modulation.

-E

MAX

MIN

x 100%

MAX

MIN

Set audio oscillator level

75 to 95%.

for 0.135 V rms (-15 dB

mW) at 1000-Hz input to

RT-980/GRC-171 as ob-

served on digital volt-

meter. Measure and

determine modulation

percentage.

Set audio oscillator

Observe that over-

level for 7.75 V rms

modulation does not

(+20 dB mW) at 1000-

occur (a minimum rf

Hz input to RT-980/

level of zero cor-

GRC-171 as observed

responds to over-

on digital voltmeter.

modulation of the

RT-980/GRC-171).

5-17