This transmitter consists in a common emitter colpitts VCO and a Class E amplifier with 50 ohm matched resonant network. The capacitance of the LC tank is given by varactor diodes. Incresing the inverse voltage on each diode, the depletion zone will increase and the junction capacitance drops... and viceversa.
Biasing the varactors with a DC offset you can change the center frequency and select channels. The Class E amplifier is matched for 50 ohm loads, you can send the signal with 50 ohm coax cable directly to a matched antenna. If you turn on the transmitter without a 50 ohm load the mosfet will blow up.
Use a switch and a relay to turn off the 30V power supply when you are not transmitting like here.
http://everycircuit.com/circuit/5568943585230848
