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Page 4-30
GNS 400W Series Maintenance Manual
Rev. A
190-00356-05
Carrier Squelch (8.33 kHz)
1.
Enable the compressor.
2.
Set the unit for 118.005 mHz, 8.33 kHz spacing, squelch enabled.
3.
Set the signal generator to 118 mHz, 85% modulation, 8 kHz audio frequency.
4.
Sweep the output level from 1.5 µV to 6.0 µV, step size: 0.2 µV.
5.
Measure the audio output in ac Vrms.
6.
Repeat steps 3 and 4 until the squelch opens (the audio is present).
7.
Store the squelch open point.
8.
Reduce the signal generator output by 6 dB.
9.
Measure the audio output in ac Vrms (hysteresis).
10.
Verify the following:
•
Squelch open point: 1.5 µV
≤
X
≤
6.0 µV.
•
Hysteresis: ac Vrms < 10 mVrms.
Noise Squelch (25 kHz)
1.
Enable the compressor.
2.
Set the unit to 118.000 mHz, 25 kHz spacing, squelch enabled.
3.
Set the signal generator to 118 mHz, 30% modulation, 1 kHz audio frequency.
4.
Sweep the output level from 1 µV to 4 µV in 0.2 µV step sizes.
5.
Measure the unit audio output in ac Vrms.
6.
Repeat steps 3 and 4 until the squelch opens (audio is present).
7.
Store the squelch open point.
8.
Reduce the signal generator output by 6 dB.
9.
Measure the audio output in ac Vrms (hysteresis).
10.
Repeat steps 1-8 for 127.000 mHz and 136.975 mHz.
11.
Verify the following:
•
Squelch open point: 1 µV
≤
X
≤
4 µV.
•
Hysteresis: ac Vrms < 10 mVrms.
