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Page 4-38
GNS 400W Series Maintenance Manual
Rev. A
190-00356-05
RF Power Output
NOTE
Except as noted below, all transmitter measurements are taken at the transmit RF
output BNC connector using a standard load of 50 ohms.
The transmitter must deliver a minimum output power shown in the below table. The power must
not vary more than three watts across the operating band as described in the com frequency range
section. Transmitter power must be measured at channels 118.500, 127.500, and 136.500.
Power Input Voltage Range (V)
127.51 13.752
27.53
Minimum Transmitter Power (W)
10 10 16
1.
Set the unit to 118.500 mHz.
2.
Turn off the microphone audio.
3.
Key the microphone.
4.
Measure the TX CW power in watts.
5.
Unkey the microphone.
6.
Repeat steps 2-5 at 127.500 mHz and 136.5 mHz.
7.
Verify the following:
•
10W com radio: 10-14 watts
•
16W com radio: 16-22 watts
Modulation Capability
•
The modulation must not be less than 70% and not greater than 99.99% with a standard
modulator signal applied to the transmitter. Modulation must be measured at channels
118.500, 127.500 and 136.500.
•
The microphone adjustment must be capable of adjusting the input signal level from 70
mVrms to 3 Vrms and maintain the specification of DO186a 2.3.3.
•
The microphone compressor must have a minimum dynamic range of 20 dB. Measure at
channel 127.000.
•
The microphone compressor must clip 3 dB above the dynamic range.
•
The microphone compressor attack time must be less than 20 msec and the decay time
must be greater than 400 msec.
1.
Apply a standard microphone test signal.
2.
Set the carrier frequency to 118.000 mHz.
3.
Key the transmitter.
