TMA44 Audio Panel Installation Manual
7 November 2017
01849-00 Issue
AB
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Trig Avionics Limited
33
Appendix A
External PTT Hook Up
Part of the installation includes the installation of PTT (Push-To-Talk)
switches that allow the use of your aircraft radio for communications
transmissions. There are three configurations that can be used, you must select
the case that best fits your installation.
CASE 1 - The PTT is built into the pilot and co-pilot yokes
Simply install the plugs from the headset into the aircraft headphone jacks.
Then use the yoke mounted PTT to transmit. No other action is required.
CASE 2 - Built in PTT only on the pilot side only
This configuration requires a modified external PTT switch plugged into the
co-pilot's mic jack – see modification details below. When the co-pilot's PTT
is depressed, this activates an internal relay that switches the mic audio to the
aircraft radio from the pilot to the co-pilot.
CASE 3 - No built in PTT switch at all
Two built-in PTT must be installed, or two external, modified PTT switches
will be required for both the pilot and co-pilot – see modification details
below.
Push To Talk Modifications
When received from the manufacturer, an after-market PTT switch opens the
mic audio path to the "ring" connection of the PTT mic plug until the button is
pressed. When the PTT is between the intercom and the headset, the intercom
function will not work unless the PTT switch is depressed. A simple
modification can be performed to allow proper intercom operation. NOTE:
This mod does not alter normal operation.
Below are some examples of typical modifications. Contact Trig Support or
the PTT manufacturer for more details if necessary.
