Wiring Harness, For connecting a Trig TT21 or TT22 Transponder Unit to a TC20 Control Unit
This is a pre-wired wiring harness which makes installation faster and trouble-free.  It may also save you delays and repair bills should you accidentally connect something incorrectly.  This wiring harness is assembled and tested using a cable tester by Larry Goddard.  It has a DB-9f connector at the TC20 end and a DB-25m connector at the TT21 or TT22 end.  It also includes power input leads for 10 to 30 VDC. The power input leads exit the DB-25m connector at the TT21 or TT22 transponder end.  The power input leads are 0.5 m long.  The 0.5 m length is perfect for installations where the TT21 or TT22 Transponder Unit will be mounted near the TC20 Control Unit (such as in front of the instrument panel in the nose of a glider).  For installations with the TT21 or TT22 Transponder Unit mounted behind the pilot please see the 3 m version of this cable below.  There is also a 1 m long version.
Note: Wiring for external "Squat" and "Ident" switches is not included.  The squat switch input is only for aircraft with built-in squat switch circuitry.  It is my understanding that a landing gear switch in a glider can not be used as a squat switch because it would cause the transponder to send incorrect information while the landing gear is down during aerotow and in the landing pattern.  The "Ident" switch is not necessary because the "IDT" pushbutton on the TC210 control unit has the same function.

Length options

0.5 m (19.7 ft.) 

1 m (3.281 ft.) 

3 m (9.84 ft.) 

5 m (16.4 ft.)