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Page Title:
Table 4-8. TRANSMIT CIRCUITS TEST PROCEDURE (Cont'd) |
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|  TM 11-5895-1141-34
Table 4-8. TRANSMIT CIRCUITS TEST PROCEDURE (Cont'd)
Step
Operation
Normal Indication
2
Set the audio signal input to 1000 Hz and
an ac voltmeter reading of 126 mv
(-11 dBm).
3
Close microphone P/T switch. Adjust
Red indicator lamp on selector module turns
threshold adjust potentiometer R1218 on
on. Audio output level of 0 dBm obtained
microphone amplifier for 0 dBm.
across 600 ohm output load resistor, shown in
test figure 4-7.
4
Increase signal input level from 126 mv to
Output signal across the 600 ohm load should
remain at 0 dBm 3 dBm.
1.26 v, an increase of 20 db to 9 dBm.
5
Connect a distortion meter across the
Distortion should not exceed 8% at these three
600 ohm load. Set oscillator to 300, 1000
frequencies.
and 3000 Hz, in sequence.
6
Remove distortion meter and return input
The output level returns to 0 dBm.
signal level to 126 mv at 1000 Hz.
7
Measure the output level at both 300 and
The output level should not decrease more than
3000 Hz while maintaining the input signal
3 db from the level at 1000 Hz.
level at 126 mv.
8
Return the input signal frequency to
Transmitting sidetone signal should be -25
2 dBm.
1000 Hz and 126 mv and connect an ac volt-
meter to 600 ohm resistor between sleeve
terminals on jack panel (fig. 4-8). Set
Headset Volume control to maximum.
4-16
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