SZ123

This small transmitter uses a hartley type oscillator. Normally the capacitor in the tank circuit would connect  at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The coil is four turns of 18swg wire wound around a quarter inch former. The aerial tap is about one and a half turns from the supply end. Audio sensitivity is very good when used with an ECM type microphone insert.   From:  radio_david#yahoo.com

Use BC548 X2 Mini FM Transmitter Bug circuit