Garmin GNC 255 Installation Manual - page 46
GTR 225/GNC 255 TSO Installation Manual
190-01182-02
Page 5-8
Rev. B
5.2.4.3 COM Audio
5.2.4.4 COM Audio Function
Activation of COM MIC 1 TRANSMIT enables MIC 1 AUDIO IN HI and causes the transceiver to
transmit.
Activation of COM MIC 2 TRANSMIT enables MIC 2 AUDIO IN HI and causes the transceiver to
transmit.
500
COM AUDIO is a 100 mW audio output that is intended to drive a headset or an audio panel.
5.2.4.5 COM Audio Electrical Characteristics
5.2.4.5.1 COM MIC AUDIO
MIC 1 and MIC 2 are standard carbon or dynamic mic inputs with integrated preamps providing minimum
70 mVrms into a 1000 Ω load.
MIC 1 and MIC 2 are set in the factory so that 100 mVrms modulates the transmitter to 85% nominally at
1000 Hz. The microphone gain adjustment is made through Configuration Mode.
5.2.4.5.2 COM AUDIO
COM AUDIO supplies 100 mW into a 500
load. This is a balanced output and the LO output must be
connected.
COM AUDIO is the summation of the COM receiver audio, COM sidetone audio, and intercom audio.
Pin Name
Connector
Pin
I/O
COM MIC 1 AUDIO IN HI
P2001
5
In
COM MIC 2 AUDIO IN HI
P2001
6
In
MIC AUDIO IN LO
P2001
20
In
Pin Name
Connector
Pin
I/O
500 Ω COM AUDIO HI
P2001
7
Out
500 Ω COM AUDIO LO
P2001
18
Out