I believe the interrogation (ATC transmit, aircraft receive) occurs at 1030 MHz, and the reply (aircraft transmit, ATC receive) is at 1090 MHz.
Mark Youkey myou...@cox.net Oklahoma City > removed from a certified aeroplane. Third, the transponder is a Bendix > KT-76A > - Frequency: 1030 MHz > - Output: "200 watts peak minimum transmitter power"
