TR-220 Multi-Function Avionics Test Set The TR-220 provides test capability for Traffic and Collision Avoidance Systems (TCAS), Distance Measuring Equipment (DME) and Transponders (Modes A, C, and S). The TR-220 features state-of-the art design technology. Microprocessor control results in easy-to-use operation that requires minimum amounts of training. Setup menu allows storage of various test parameters to facilitate quick recall of test conditions. NSN 6625-01-527-4732 {loadposition tr-220em}