TRIG TT21 Mode S Transponder

The Trig TT21 is the smallest, lightest Mode S general aviation transponder at just 500g. This two part mode S transponder, includes an integrated altitude encoder, can fit into the smallest of aircraft.   The Trig TT21 is fully certified and compliant with all the transponder requirements. With an ultra compact front panel LCD controller and a small transponder body not much larger than a pack of cards, this new transponder will squeeze into any aircraft. Ideal for light sport and microlight aircraft as well as conventional light aircraft. The low power design (5 watts) means that it can also run on batteries for gliders and balloons.

The Two part system consists of a Control Head which fits to the aircraft panel, and a transponder body which can be fitted elsewhere on the aircraft with a light weight cable connecting the two. Aircraft power and the antenna cable also plug into the rear box. The Transponder Controller head requires less than 70mm behind the panel and can fit either a standard 57mm instrument cut out or smaller 42 x 57 mm cut out.

Mode S for Light Aviation
The TT21 transponder is an ED-73B Class 2 compliant Mode S level 2 datalink transponder, with support for extended squitter. It meets all the requirements for Mode S elementary surveillance transponders in Europe for aircraft flying below 15,000 feet and with airspeeds below 175 knots. It can be used for both IFR and VFR flight.

The TT21 also supports 1090 MHz Automatic Dependent Surveillance Broadcast (ADS-B) extended squitter, known as “ADS-B out”. This provides improved airborne surveillance, vital information for airport ground surveillance, and is a key feature of future airspace plans. An appropriate GPS receiver is required to enable the ADS-B capability.

Main Features and Benefits

• Low Weight
• Minimal Panel Space
• Low Power Consumption
• 130 Watts Nominal Output
• Integrated Altitude Encoder
• Simple Installation
• Easy to Use Rotary Knobs
• Support for ADS-B Out

Flexible Installation
The TT21 system can be easily fitted to aircraft even when there are space and weight constraints. The front panel controller fits into any panel, and takes less space than a standard instrument. Only a few centimetres are needed behind the panel to allow room for the connector and the static port interface. This means that the TT21 transponder is not just suitable for conventional light aircraft; it can be fitted into gliders, antique aircraft, and flex-wing microlight panels. The control panel is splash proof for open cockpit installations.

A lightweight cable runs from the control panel to the transponder unit which can mounted anywhere in the aircraft. The transponder unit then connects to the antenna and aircraft power supply. A quick release latch secures the main unit to the mounting tray, allowing it to be easily removed for security.

Low Power Design
The TT21 has one of the lowest power consumptions for any transponder. With typical power consumption of around 5 watts, it can operate from battery power for gliders or balloons for long duration flights. In powered aircraft you can be sure that the TT21 is not making heavy demands on your electrical system.

Operating Controls
The front panel controller has easy to operate rotary controls, and a simple layout. The clear LCD screen shows the Squawk Code, reported Flight Level, and operating mode of the transponder. An altitude encoder is built into the controller, so no extra boxes are needed to complete the transponder system. Finally, the controller also acts as the configuration module for the combined system. With the controller remaining attached to the aircraft, swapping the TT21 transponder box is possible without needing any reprogramming of airframe settings.

Light Weight
The TT21 system weighs less than 500 grams, with less than 100 grams in the front panel controller. For all aircraft low weight translates into more payload and better efficiency, but for microlight aircraft where certification weight limits are tight the low weight of the TT21 system may make it possible for the first time to fit a transponder.