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Regenerative Receivers-explanation

Discussion in 'General Electronics Discussion' started by BRAVOKILO, Jun 11, 2018.

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    Jun 11, 2018
    Hi friends,

    Been building regens and came across explanation how Armstrong regens worked. As we all know he placed a secondary on the antenna coil and fed it back to the grid of the tube. The explanation was that a signal is re-amplified over and over again. In fact, I read about "quenching" since the original signal remained in the tube. Sort of a reset was needed. In fact, am building a single transistor FM receiver with a transistor pair cycling at 21khz to reset the FET FM receiver.

    Then I came across an explanation on how modern transistor regens work and many circuits did not have the inductive feedback of Armstrong regens. In fact a capacitor across the C and E of the transistor is said to feedback signals from the C to the E and keeps the circuit oscillating. An explanation on how it works (Talking Electronics, 27 Mhz Links) is that the RX is a very low power oscillator and WHEN A SIGNAL APPEARS OF THE SAME FREQUENCY, THE OSCILLATION IS AFFECTED CHANGING THE CURRENT DRAW. This change in current (or voltage) is sensed by an audio amplifier. There is no quenching issues. And the incoming signal is not said to be picked up and regenerated.

    Will appreciate comments pls.
  2. Audioguru


    Sep 24, 2016
    A super-regen quenches and automatically works but an ordinary regen receiver needs you to fiddle with a regen potentiometer for it to work poorly.

    Guess what? The change in current draw is AM (amplitude modulation). In addition to having poor sensitivity and poor selectivity, a regen or super-regen receives all the static and other interference of AM and the thing must be tuned to one side of an FM station to detect FM. But tuning to one side reduces its sensitivity and probably causes it to have interference from another station on that side.

    The thing you are making quenches at 21kHz then it will produce a 4kHz beat tone squeal because today all FM stations are stereo with a 19kHz stereo pilot. A regen and super-regen were invented long before FM stereo.


    Jun 11, 2018
    Thanks for that info Audioguru. Now I know if that darn thing sqeals.
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