You need DC power, an audio source to transmit, and a wideband FM receiver to act as the IF strip. The reciever is connected to the Gunnplexer mixer. Quick and dirty transmit can be simply a 9v battery and the speaker output of an HT in parallel. A better solution is a variable DC regulator combined with an audio amplifier, which gives fine tuning and a mike input. IF and discriminator may be provided by a scanner, or a dedicated receive circuit board, connected to the Gunnplexer mixer.
Microwave heating can especially damage the eyes and testes.
WWII secret X-radar used brass bed frame tubing as waveguide. Robert Gunn invented this negative resistance oscillator diode. Tune your gunnplexer with its antenna, to prevent VSWR pushing. X-band Gunns temperature drift typically 1 MHz per 3 degrees. Warm up Gunnplexers at least 10 min before tuning or operating.