Trig TT21 Compact Class 2 Mode S Transponder

The Trig TT21 is a compact two part transponder system, which includes an integrated altitude encoder.

In design and technology it is equivalent to the TT22, however, the transmitted output power of the TT21 is lower at 130watts, qualifying the unit as a Class 2 transponder.
Class 2 transponders are suitable for aircraft cruising slower than 175 knots, and operating below 15,000 feet, VFR or IFR. If your aircraft is capable of exceeding these operating limts then you need to fit the TT22

Lightweight – lesss than 500 grams
Minimal Panel Space
Low Power Consumption
11-33 Volt Operation
130 Watts Output (nominal)
Integrated Altitude Encoder
Simple Installation
Support for 1090ES ADS-B Out

The TT21 can be mounted in a standard 57 mm (2¼ inch) instrument hole, or where space is at a premium.

The TT21 is TSO approved for fitting to European and FAA registered aircraft.