The Technisonic TFM-550 is a three band, frequency agile, airborne VHF/UHF FM transceiver intended to provide radio communications on every channel currently available in the VHF low band (30 to 50 Mhz), VHF high band (138 to 174 Mhz) and the UHF band (403 to 512 Mhz). This synthesized multi-band transceiver offers narrow band (12.5 KHz) or wide band (25.0 Khz) channel spacing on any or all of it's 600 channels of preset memory (200 channels per band) and can operate without restriction on any frequency pair in any band. Each channel is capable of storing a transmit frequency, a receive frequency, a separate CTCSS tone and/or a DPL/DCS code for each transmit and receive frequency, and a nine character alpha numeric identifier for each channel. All data and software controlled functions are via the 12 button, front panel keypad. Operating frequency, alpha numeric identifier and other related data re presented on a 96 character, four line, LED matrix display.The TFM-550 is compatible with existing TFM-138 series installations and an be installed to a single FM audio controller position, in which case one band at a time can be accessed y the operator. Alternately, the TFM-550 can be installed to 2 audio controller positions (typically F1 and FM2), which will allow for simultaneous peration on UHF and either VHF hi band or VHF low band.