1957 3 Transistor Portable

1957JanPEcoverSixty years ago this month, the January 1957 issue of Popular Electronics showed how to put together this 3 transistor superheterodyne receiver for the broadcast band. The set employed three transistors. A 2N136 served as oscillator and mixer. A 2N135 served double duty in a “reflex” arrangement as both IF amplifier and the first stage of audio amplification. Transistors were expensive, and the single transistor was capable of amplifying the 455 kHz RF and the audio simultaneously. A 2N170 served as the final AF amplifier to drive a magnetic earphone.

A signal generator was required for alignment once the simple receiver was put together. No external antenna was necessary, although a wire a few inches long would improve the sensitivity.

The set could be installed in a clear plastic case, with the inside spray painted to the desired color.


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