Trig

Trig Avionics Limited

Company Overview
Trig Avionics Limited was founded in January 2004 to develop innovative avionics products for general aviation. Based in Edinburgh, Scotland, Trig are specialists in low power, high tech solutions to existing and emerging requirements in general aviation avionics. Trig is a privately held limited company.

New TT23 and TT23G Transponders
The TT23 series of transponders have all the same great features of the TT22, but in a much smaller size, and with an optional built-in GPS engine. The TT23G replaces the combination of TT22 and TN72 GPS. The TT23 doesn't have a built-in GPS. The TT23G does have a built-in GPS.

Trig Flow Chart - Which GPS for ADS-B OUT for Experimental and non-Experimental Sailplanes
There are a lot of confusing rumors about which GPS to use to legally get ADS-B 1090 OUT in the USA. In past years, if you had a experimental sailplane, or a Light Sport aircraft, you could use the Trig TT22 transponder with a TN72 GPS, but sailplanes certificated in the Standard Airworthiness category needed to use the much more expensive and much larger Trig TN70 GPS - and the huge TA70 GPS antenna. Fortunately, in recent years, Trig has worked with the FAA and FCC to get approvals for using the lower cost TN72 GPS in sailplanes certificated in the Standard Airworthiness category - as long as the sailplane won't fly above 18,000 feet, or in Class B or C airspace, or over the Gulf of Mexico. Please see the link below for a flow chart detailing how to select the correct GPS for your application. Those restrictions aren't a problem for mail sailplane owners, so 99% of sailplane owners have installed the TN72 GPS in their sailplanes. The new Trig TT23G with built-in GPS engine works in the same applications in which the TT22 and TN72 were used for previously.
Trig - Which GPS for Glider.pdf - Note: It's 2 pages.

STC for TT22 with TN70 - And the TT23 and TN70
If you have a sailplane certificated in the Standard Airworthiness category, and you need to fly in Class B or Class C airspace, or above 18.000 feet, or over the Gulf of Mexico, then you'll need to install the TT22 and TN70 and a Peregrine Airspeed Switch. Peregrine owns the STC for the combination. The STC documents are available upon request. The new Trig TT23 is not on that STC, but Trig is working on that. As of December of 2025, Trig has completed the flight testing phase of the TT23 STC. They are optimistic that the STC will be completed in early 2026. Until then, the TT22 and TN70 are the only legal solution. Once the STC is completed, the use of the TT23 transponder with a TN70 GPS engine and TA70 GPS antenna and Peregrine Airspeed Switch will provide a fully approved system for all sailplane types and in all airspace.

TY91 Panel Mounted Aviation Radio
The new TY91 radio is a very interesting product. It looks great in the panel next to a Trig TT21 or TT22 transponder. The dual-monitor function makes it possible to hear transmissions on the standby frequency if nothing is being received on the main frequency - enhancing safety.

TT21 & TT22
The TT21 and TT22 are a very interesting transponders. They are Mode S transponders with built-in altitude encoders, and remote heads - at a great price! Also, the TT21 uses half the power used by the Becker ATC4401 - which is very impressive. You can see a current draw comparison that includes the current required by the altitude encoder used by a Becker transponder. The TT21 is a Class 2 transponder with 125 Watts of transmit power which is rated for use up to 15,000 feet. The TT22 is a Class 1 transponder with 250 Watts of transmit power. Class 1 transponders are used on high performance aircraft – those cruising faster than 175 knots, and operating above 15,000 feet.

ADS-B Out
The Trig TT-21 does not meet the FAA 2020 ADS-B Out requirement for powered aircraft (that gliders are exempt from), and therefore also may not be suitable to provide ADS-B out in gliders should gliders lose that exemption in future. The higher power Trig TT22 does meet the FAA 2020 ADS-B Out requirements. Both the Trig TT21 and TT22 are usable as basic transponders (without 1090ES Out) in the USA, now and after 2020.

A Transponder in Every Sailplane
I strongly believe that every sailplane should have a working transponder in it. I'm sure you will think that is because I sell them. But the main reason is that I fear that in the future a collision will occur between a glider (without a transponder) and a commercial airliner. In addition to the tragic loss of life, we soaring pilots may lose access to airspace. It is my sincere hope that this transponder will break down many of the barriers which have kept glider pilots from installing transponders in their gliders. The units small size and low power consumption make it very attractive.

Trig Transponder Example Systems
The link below takes you to a page with several complete Trig transponder example systems.
https://www.cumulus-soaring.com/store/trig-example-systems-transponders

Trig Radio Example Systems
The link below takes you to a page with several complete Trig radio example systems.
https://www.cumulus-soaring.com/store/trig-example-systems-radios

Brochure and Manuals
TT23 and TT23G Brochure, Operating Manuals and Installation Manuals
https://trig-avionics.com/support/install-and-user-manuals/

Transponder Antenna Tips
DG has an excellent document on their web site with details on how to mount transponder antennas to gliders.
http://www.dg-flugzeugbau.de/Data/TN-DG/service-infos/2004-53-e.pdf