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GNS 400W Series Maintenance Manual
Page 4-21
190-00356-05
Rev. A
4.5.3 General Test Conditions
Covers and Shields
All comm board tests are performed with covers and shields in place.
Comm Frequency Range
The comm radio receives and transmits on all frequencies from 118.000 to 136.975 mHz in the 25
kHz channel mode and from 118.005 to 136.990 mHz in the 8.33 kHz channel mode.
4.5.4 Comm Board I/O Description
The following pin descriptions are for J2, the rear panel comm board connector. The pin
descriptions can aid in the fabrication of test cables, test setup, and troubleshooting. Refer to
Figure A-1 for the location of J2.
PIN
NAME
I/O
DESCRIPTION
1 UNSQUELCHED
AUDIO
O
Not used on 400 series.
2
COMM IF AGC TEST
O
This is the IF AGC output. It has a 10 K output
impedance, and should be measured with a high
impedance voltmeter.
3 SQUELCH
/
COMPRESSOR TEST
I
This input disables the compressor and opens the
squelch when input is low. Vin low = .1 Volts @ 5 mA.
This input is designed to be operated from a hard switch
or relay. The compressor disable function can be
controlled serially for ATE.
4
COMM MIC KEY
I
This input is the PTT line. A signal less than 3 volts or a
the resistance to ground less than 100 ohms shall
activate the transmitter. The transmitter is inactive when
the resistance to ground is greater than 1 megohm.
5
INTERCOM MIC HI
I
Microphone intercom audio input. This input will supply
the microphone with a 9 volt bias through a 610 ohm
resistance.
6
COMM MIC AUDIO HI
I
Microphone audio input. This input will supply the
microphone with a 9 volt bias through a 610 ohm
resistance.
7
COMM AUDIO HI
O
Comm radio audio output will supply 100 mW to a 500
ohm load. This audio is the summation of the receiver,
microphone intercom and sidetone.
8
COMM AUDIO IN HI
I
-----
9
NAV AUDIO IN HI
I
-----
10
AUX AUDIO IN HI
I
-----
11
AIRCRAFT POWER
I
Aircraft power input.
12
AIRCRAFT POWER
I
Aircraft power input.