User's Manual

TY91/TY92 VHF Radio Installation Manual 11 April 2012
00839-00 Issue AA
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Trig Avionics Limited 21
pulled below approximately 4 volts. The input should be connected to a
momentary switch on the yoke or on the microphone.
5.6.7 Intercom Key Input
The intercom key switch input allows the intercom function to be selected
using a remote switch, or permanently enabled by grounding the pin inside the
connector. The input is active low, and will be asserted when the voltage to
ground is pulled below approximately 4 volts.
If this pin is tied low, the intercom function depends on the vox operated
squelch.
Note: It is possible to combine both the key switch and the vox
activation, or to use only one. To use only the switch, wire the switch
to the intercom key input and select the vox squelch to the lowest
setting during configuration. To use only the vox, wire the intercom
key input to ground, and configure the squelch accordingly.
5.6.8 Transmit Interlock
When two VHF radios are mounted in an aircraft the transmit interlock of one
can be connected to the transmit PTT key of the other radio. When the other
radio transmitter is keyed, the squelch threshold of this radio is increased to
minimise break-through between one radio and the other.
Note: To improve the performance when using two radios, the
antennas should be as far apart as practical – for example on the top
and bottom of the fuselage.
5.6.9 Auxiliary Audio Input
This input is continually routed to the headphone and cabin speaker outputs. It
is intended for annunciators and identification tones.
Note: The audio bandwidth on the auxiliary input is limited, and is
not ideal for MP3 players or other entertainment inputs. If such a
device is connected, the mute settings should be enabled in
configuration mode so that radio reception and transmission takes