Demo of the 'Heathkit Twins (HR-1680 Receiver/HX-1681 Transmitter)

Brief demo of a Heathkit HX-1681 (CW only) transmitter built from a kit around 1978. Some capacitors have been replaced in the transmitter and some troubleshooting for no output on the 15M band, and low output on the 10M band. This was traced to de-tuned bandpass filters on the HFO/Mixer circuit board - the bandpass filters uses an unusual style of trimmer capacitor, the rotors of which had become loose and easily detuned by vibration or impact shock. Once the bandpass filters were set correctly, a small dab of (easily removable) 'goo' was placed on the trimmers to mitigate this issue. The matching HP-23B power supply was completely rebuilt with all new capacitors, resistors and rectifiers. The receiver has has its power supply filter capacitor and rectifier diodes replaced, safety capacitors fitted to the line input, plus some 'tidying-up' work done by the previous owner.