N3FRQ's Homebrew Corner

12-volt 1-tube Regenerative Receiver:

    This article first appeared in the Delaware Valley Historic Radio Club's Oscillator.

12-volt 1-tube Reflex Receiver:

    I was so encouraged by the success of the simple regenerative set that I undertook the design of a much more elaborate one-tube set using a "reflex" circuit.  In this receiver the signal passes through the tube twice:  first, as radio frequencies and then a second time, as audio.  Because there is considerable RF gain before the detector, this radio is far more sensitive than a simple regenerative set.
    This is not a project for beginners.  The design employs a lot of hard-to-get and potentially expensive parts, almost enough to build a rudimentary superheterodyne.  You'll probably need a sweep generator to get the tunable band-pass filter working correctly.  You should be prepared to reengineer the circuit to suit the parts on hand.

Simple battery tube radio based on the PGXS crystal set.

Simple Regenerative Receiver

1-Tube Regen Based on Above