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Page Title:
Table 4-7. TESTING RECEIVER CIRCUITS TEST PROCEDURE (Cont'd) |
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|  TM 11-5895-1141-34
Table 4-7. TESTING RECEIVER CIRCUITS TEST PROCEDURE (Cont'd)
Step
Operation
Normal Indication
2
Set the audio signal source to 1000 Hz and
With the 600 ohm load in place at the jack
155 millivolts as measured by voltmeter.
panel as shown in figure 4-5, a reading of
This corresponds to an effective input
0 dBm should be obtained across the load.
level of -20 dBm. Refer to test connec-
If necessary adjust threshold adjust pot B17
tion diagram, figure 4-4.
(fig. 4-2) in the volume control module to
obtain 0 dBm.
3
Increase the signal input from 155 mv to
The output across the 600 ohm load shown in
4.90 v at 1000 Hz.
test figure 4-5 should remain at 0 dBm
3 dBm.
4
Connect a distortion meter across the 600
Distortion should not exceed 8%.
ohm output load. Measure the percentage
distortion at the following frequencies:
300, 1000, 3000 Hz. Input level is 4.9 v.
5
Reduce input signal to 155 mv at 1000 Hz.
Output level should return to 0 dBm
(0.755 volts) across the 600 ohm load.
Reduce frequency to 300 Hz maintaining the
The output should not decrease more than 3 dB
155 mv input amplitude.
(0.707) of the output level at 1000 Hz.
Increase the input frequency to 3000 Hz,
The output should not decrease more than 3 dB
maintaining the 155 mv input amplitude.
(0.707) of the output level at 1000 Hz.
6
Restore the condition of 0 dBm output for
The output noise level in the absence of
155 mv input at 1000 Hz. Disconnect the
signal input should not be greater than
audio oscillator and short circuit the
-45 dBm.
attenuator output.
4-8
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