The following is a list of popular transponders used by GRT customers. The Trig TT22 is recommended for its price, remote interface and ADS-B Out (Extended Squitter) capability. This list is not all-inclusive; our built-in encoder will feed most Mode C and Mode S transponders including Becker, Microair and King, with support for both Grey code and serial encoder data.
|Manufacturer||Model||Type||Mount||Retail Price||Available through GRT|
|Garmin||GTX 327||Mode C||Panel||$1,789||No|
|GTX 330 / 330-ES||Mode S||Panel||$3,649||No|
|TT21|| Mode S
|TT22|| Mode S
|Sandia||STX 165R||Mode C||Remote||$1,550||Yes|
Retail prices are from a reputable dealer for comparison purposes only – may not be current.
Remote Mount interfaces apply to HXr only.
*GRT price includes single-display remote serial adapter for HXr. Dual-display adapter is available for $175. Dual-display adapter allows two display units to control transponder, providing redundancy if one display unit is lost.
†TT21 does not comply with U.S. 2020 ADS-B mandate, which requires Class 1 transponder (higher output wattage).
Here you’ll find all user documentation created by GRT for popular transponder options, including mounting templates and supplements for wiring, setup and use.
|Trig TT21/TT22 Supplement for HXr||A2||5/28/2014|
|Trig TT21/TT22 Mounting Tray and Overall Dimensions||A||11/06/2012|
|Trig TT21/TT22 Serial Adapter Dimensions*||1||11/06/2012|
|Trig TT21/TT22 Wiring Diagram for HXr||1||11/06/2012|
|Trig TT22 Unit Photos*||1||11/06/2012|
|Garmin GTX327 GRT Supplement||A||12/15/2014|
|Garmin GTX330 GRT Supplement||A1||10/23/2013|
*Note: Trig serial adapters have the same dimensions as the drawings and photos shown, but now have a metal case.