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GNS 400W Series Maintenance Manual
Page 4-41
190-00356-05
Rev. A
•
The sidetone audio level must be capable of adjusting from 1.4 to 7.07 Vrms when the
transmitter is modulated with a standard microphone input signal.
•
The nominal sidetone audio level must be set to 1.4 Vrms into a 500 ohm load when the
transmitter is modulated with a standard microphone input signal. Measure at 118.500,
127.500, and 136.500.
1.
Set the unit to 118.500 mHz.
2.
Generate and apply a standard microphone audio signal.
3.
Key the microphone.
4.
Measure the RMS audio level.
5.
Unkey the microphone.
6.
Repeat steps 1-5 for 127.500 mHz and 136.500 mHz.
7.
Verify audio level is between 1.12 and 1.68 Vrms.
Signal Name
Signal Pin
Reference Name
Reference Pin
Load
COMM AUDIO HI
J2-7
COMM AUDIO LO
J2-19
500 Ohms
Spurious Emissions
Spurious emissions below 1000 mHz must not exceed -36 dBm with a measurement bandwidth of
1 kHz. Above 1000 mHz, spurious emissions must not exceed -30 dBm with a measurement
bandwidth of 10 kHz. Set the spectrum analyzer to the following:
•
Reference Level: -30 dBm
•
Center Frequency: 600 mHz
•
Span: 800 mHz
•
Marker ON
1.
Set the unit to 118.500 mHz.
2.
Key the microphone.
3.
Measure the peak using measurement averaging.
4.
Unkey the microphone.
5.
Verify result is
≤
36 dBm.
