This micro-transmitter for the 27 MHz band was found in a 1976 technical documentation. The critical component is the tunnel diode, and the frequency is determined by the crystal. The coil should have around 0.3 uH of inductance, preferably with an adjustable core to obtain the best performance point. The circuit is powered by a single battery and the adjustment potentiometer R1 can be 470 ohms of wire. The antenna is of the telescopic type. Rx must be obtained experimentally with values between 1 ohm, and 4.7 ohms.
