TT21/TT22 Transponder Installation Manual 22 August 2017
00560-00 AP
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4 Trig Avionics Limited
The TT21/TT22 operates on 11 to 33 Volts DC.
A two wire data link is used to connect the TT21/TT22
and the controller.
The controller is powered from the transponder.
The on-off switching is on the controller, and switches this
input.
External IDENT switch input.
External standby input for dual transponder installations.
Allows automatic flight/ground mode switching for
aircraft with a squat switch.
ARINC compatible suppression bus signal used in aircraft
with other pulse equipment, such as DME. This pin is
both an input to and output from the transponder.
Connection to a GPS supplying position input for ADS-B
position reporting.
Connection to a traffic display.
2.2.2 TC20 Controller Unit
The TC20 controller has a single 9 way D-type connector. It provides the
following services:
The controller receives power from the transponder.
A two wire data link is used to connect the
TT21/TT22 and the controller.
The on-off switching is on the controller, and controls
this output.
An additional serial output on the TC20 provides
pressure altitude information that can be used for baro-
aiding by certain GPS receivers.