The Technisonic TDFM-136 Project 25 (Phase I) compliant airborne VHF/FM transceiver provides digital or conventional analog FM communications on every currently available channel from 136 to 174 MHz within the General Radio Service VHF/FM High Band. The TFDM-136 operates on the Common Air Interface described in TSB102 and is capable of multimode operation for 25 kHz analog, 12.5 kHz analog and Project 25 12.5 kHz digital modulation on a channel by channel basis. Operational data can be entered into 200 non-volatile memory positions (channels) via front panel 12 button key pad, or downloaded from a PC. Mode select and function control are also via the keypad. The TDFM-136 transceiver is panel mounted (standard Dzus) and completely self contained in a 8.0 x 3.00 x 5.75 inch chassis weighing just 3.1 pounds. The Technisonic TDFM-136 Transceiver is compliant with RTCA DO-160D categories relating to Electrostatic discharge,Vibration, Overpressure, Humidity, Temperature and Altitude, Magnetic Effect, Power IInput, Radio Frequency Susceptibility, Voltage Spike, Operational Shock and Crash Safety, Audio Frequency Susceptibility, Decompression, RF Emissions (Cat D) as well as with the more stringent DO-160C, Part 21, Category Z with respect to RF Emissions.