The transmitter is a very simple crystal oscillator. The heart of the circuit is the tuned circuit consisting of the primary of
the transformer and a 10p capacitor. The frequency is adjusted by a ferrite slug in the centre of the coil until it is exactly the
same as the crystal. The transistor is configured as a common emitter amplifier. It has a 390R on the emitter for
biasing purposes and prevents a high current passing through the transistor as the resistance of the transformer is very
low. The "pi" network matches the antenna to the output of the circuit.