Garmin GNS 530AW Installation Manual - page 71
500W Series Installation Manual
Page 4-17
190-00357-02
Rev. D
4.7 COM/VOR/ILS Audio (GNS 530W only)
4.7.1
COM/VOR/ILS Audio Function
Activation of COM MIC KEY enables COM MIC AUDIO and causes the transceiver to transmit.
500
Ω COM AUDIO and 500Ω VOR/ILS AUDIO are 100 mW audio outputs that are intended to drive a
headset or an audio panel.
Momentarily depressing the COM REMOTE TRANSFER button toggles the active and standby COM
frequencies. Momentarily depressing the VLOC REMOTE TRANSFER button toggles the active and
standby VLOC frequencies.
The COM REMOTE TRANSFER input may be used for EMERGENCY operation of the COM
transmitter. If the remote transfer switch is depressed for two seconds, the active COM frequency
changes to 121.50 MHz. Once the emergency frequency is activated through COM REMOTE
TRANSFER, GNS 530W COM transceivers with COM software 4.01 or later, ignore inputs from the
front panel controls for COM selections only. The pilot may exit this independent mode—restoring
COM selection control to the front panel knobs and buttons—by momentarily depressing the COM
REMOTE TRANSFER switch.
When TRANSMIT INTERLOCK is active, the GNS 530W COM receiver sensitivity is decreased. This
input is intended to reduce interference from other transmitters in the aircraft. The TRANSMIT
INTERLOCK input should be connected to the PTT input of other transmitters in the aircraft. If
connected to multiple PTT inputs, these connections must include diode isolation or multiple radios
transmit simultaneously.
4.7.2
COM/VOR/ILS Audio Electrical Characteristics
4.7.2.1 COM MIC KEY
Pin Name
Connector
Pin
I/O
COM MIC KEY
P5002
4
In
This input is considered active if either the voltage to ground is <1.9 V or the resistance to ground is
<375
Ω. This input is considered inactive if the voltage to ground is 11-33 VDC.
4.7.2.2 COM MIC AUDIO, INTERCOM MIC AUDIO
Pin Name
Connector
Pin
I/O
COM MIC AUDIO HI
P5002
6
In
COM MIC AUDIO LO
P5002
18
In
INTERCOM MIC HI
P5002
5
In
INTERCOM MIC LO
P5002
17
In
COM MIC AUDIO and INTERCOM MIC each have a 520
Ω AC input impedance and supply the
microphone with a 9 V bias through 620
Ω.
COM MIC AUDIO is set in the factory so that 275 mV
RMS
modulates the transmitter to 80% nominally.
The microphone gain adjustment is made through Configuration Mode.
When a 125 mV
RMS
signal at 1000 Hz is applied to the INTERCOM MIC input, the level on the COM
AUDIO output is not less than 7.07 V
RMS
.