Dispelling the mysteries of radio. A series featuring a variety of practical circuits for the set builder and experimenter. This month: A double-conversion superhet receiver for SW bands (Prescalers, Mixers, and Oscillators)

Last month’s article covered the advantages and drawbacks of the superheterodyne (or superhet for short) receiver. A design for a mixer/oscillator unit with a 1·6MHz intermediate frequency (i.f.) output was described. Raising the i.f. to 1·6MHz, instead of the more usual 455kHz, reduces susceptibility to second channel interference, the major defect of the superhet.

This final part deals with the intermediate frequency amplifier, which provides most of the selectivity and gain. Teamed with last month’s 3-Band SW Superhet Tuner/Mixer, it forms a high performance receiver for the shortwave listener.