TRIG TT21 and TT22 Transponders

Reference: TT21 - 00710-00



Transmitter Output
Kit Type


Warranty Policy


Delivery Policy


Return Policy

Chosen by pilots around the world Trig’s compact transponders are the best choice for good reason.

Fitting in the tightest panel space the innovative design saves weight and space. Trig is ‘better by design,’with Mode S technology that makes you visible to commercial, military and GA traffic, as a result transiting busy airspace becomes more predictable and stress free. Trig transponders are future proof too – the growing use of ADS-B further enhances your visibility and flight safety. Unlike other brands Trig transponders meet the very latest certification standard for ADS-B, FAA TSO-C166b.

Designed to be easier to use, with a clear bright display the controller even comes with a built in altitude encoder!  Join other pilots who have made Trig their compact transponder of choice – you’ll be in great company.

Specification TT21 Transponder TT22 Transponder
Type Transponder Class 2 Mode S level 2els ADS-B Class B0 Transponder Class 1 Mode S level 2els
ADS-B Class B1S
Certification ETSO C88A, C112C, C166A
TSO C88b, C112c, C166b, approved for IFR and VFR flight
Compliance ED-73C, DO-160F, DO-178B Level B, DO-254
Level C, DO-260B, DO-181D
Supply voltage (DC) 9-33 V
Typical consumption (at 14v) idle: 0.15 A active: 0.28 A idle: 0.15A active: 0.34 A
Nominal Transmitter Power 130 W at connector 250 W at connector
Operating temperature for the transponder -40°C to +70°C
for the controller -25°C to +70°C
Cooling requirement no fan required
Weight (hardware back box) 440g / 0.8 lbs
Weight (TC20 control head) 90g / 0.11 lbs
Dimensions (mm) controller: H 44 x W 63 x L 54 mm
transponder in tray: H 48 x W 68 x L 160 mm
Dimensions (inches) controller: H 1.8 x W 2.4 x L 2.1 inches
transponder in tray: H 1.8 x W 2.6 x L 6.2 inches

  • All Trig products come with a two year warranty, starting from the day of installation
  • Installation manual and Operating manual (in English, German and French)
  • Installation kit (including plastic brackets for round mounts)
  • Tray
  • EASA Form One

What is the difference between the TT21 and the TT22?
Both models have the same physical dimensions and advantages of size and ease of installation. The TT21 is a 130 watt Class 2 transponder; this makes it ideal for light sports and regular GA use. The TT22 is a 250 watt Class 1 transponder, ideally suited to higher performance and/or high altitude performance types.

In the U.S. the FAA has stated that Class 1 transponders must be used to be ‘2020 complaint’ For U.S. customers Trig recommends the TT22 unit for this reason.

Is the controller display visible in all lightling conditions?
Yes! The LCD display is clear and crisp in all lighting, full sunlight generates a very clear contrast and in dull or dark lighting the inbuilt lighting ensures the unit remains clear and legible. The controller has a backlight and manual dimming can be selected to increase or decrease brightness.

Is the controller easy to use?
Yes! One handed operation is simple. The Squawk code is easily entered using fingers to rotate the ‘CODE’ dial whilst the thumb is used to press the ‘ENT’ key. All operations can be performed whilst wearing flying gloves.

How does the compact fit or the round mount installation work?
Complete units ship with the necessary parts to enable you to choose to install the transponder either as a compact mount or 2 ¼ “ full round. The kit includes a template to assist you in cutting an accurate compact mount hole in the panel. If a full round mounting is required then you simply fit the plastic blanks above and below the body on the TC20 controller (included in the box). Once installed the full round is a tough and durable solution and is particularly suited to classic and vintage types.

Can I use the Transponder in open cockpit fllying?
The TC20 controller is splash proof. This makes it suitable for use in open cockpit aircraft, where the weather can sometimes be in the cockpit and not just outside it!

In Europe, how do I get a free minor change?
Free minor changes for the TT21 and TT22 are available, see our minor change library. You may also consider the alternative EASA approval called CS-STAN this is especially suited to VFR aircraft.

Does the TT22 have an STC?
Yes, Trig has a free STC with an AML list of over 576 types.

You can find the TT22 STC here -

In the U.S. installing a compliant ADS-B Out solution (in a certified aircraft) requires your Trig transponder to utilise a certified WAAS GPS, this provides a compliant ADS-B position source. The FAA also requires that a certified ADS-B installation is completed in accordance with an FAA STC approval (Supplementary Type Certificate).

Our ADS-B STC’s are available free of charge and cover hundreds of aircraft types. Trig STC approvals allow the use of popular WAAS GPS navigators too – making installation more practical and cost-effective. Our TA70 GPS antenna has also been added to our STC equipment list.


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TRIG TT21 and TT22 Transponders



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