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Page 4-26
GNS 400W Series Maintenance Manual
Rev. A
190-00356-05
8.
Measure the SNR (average 10 readings). Verify the following: (SNR with TX interlock
disabled) – (SNR with TX interlock enabled) > 0.
Signal Pin
Signal Name
Reference Pin
Reference Name
Load
J2-7
COMM AUDIO HI
J2-19
COMM AUDIO LO
500 Ohms
Audio Output Requirements
•
With the compressor enabled, the rated audio output must be 7.07 Vrms into a 500 ohm
load.
•
With the compressor enabled, the volume control must be capable of reducing the audio
level from 7.07 Vrms to 22 mVrms into a 500 ohm load.
•
Verify that with the compressor enabled, the squelched audio does not exceed 2 mVrms
when the volume control is set to rated audio.
1.
Enable the audio compressor and the squelch.
2.
Set the channel spacing to the 25 kHz mode.
3.
Generate an RF signal with RF carrier frequency of 127.000 mHz, 30% modulation,
modulation frequency of 1,000 Hz, RF input level of –87 dBm (20 µV).
4.
Set the volume control to deliver rated audio.
5.
Measure the audio output level.
6.
Set the volume control to minimum output. Increase the RF input level to –33 dBm
(10,000 µV).
7.
Measure the audio output level.
8.
Set the volume control back to rated audio.
9.
Remove the RF signal to close the squelch.
10.
Measure the audio output level and verify the following:
•
Rated Audio Output: Audio Output > 7.07 Vrms
•
Minimum Volume Output: Audio Output < 22 mVrms
•
Squelched Audio Output: Audio Output < 2 mVrms
Signal Pin
Signal Name
Reference Pin
Reference Name
Load
J2-7
COMM AUDIO HI
J2-19
COMM AUDIO LO
500 Ohms