matt weber ) writes:
On Sat, 13 Nov 2004 07:20:09 GMT, m II
wrote:


Is the Superheterodyne set over rated?
Useful Bandwidth control and true synchronous detection are things you
cannot do with a Regen. Try receiving SSB or FM with a Regenerative receiver.


You most definitely don't need a synchronous detector for SSB reception;
indeed there is nothing to synchronize to. One can argue that the "direct
conversion receiver", ie a mixer and oscillator that translates the signal
directly to audio, is just a variant on a regen set to oscillate in order to
likewise beat the signals down to audio. A regen does have its limits
when it comes to SSB, including the lack of selectivity and since they
were built for simplicity, lack of stability.

Synchronous detection is not need for FM, either. What may be fooling you is
that one way to detect FM is to use a phase locked loop that tracks the
incoming signal; the feedback voltage hence follows the modulation of the
signal and recovers the audio. There are plenty of other FM detectors, but
yes the regen isn't usually one of them. Theoretically it can be used
like any AM detector to demodulate FM by mistuning and "slope detection".


The BEST feature?
Simpllicity. You could build a fairly useable radio with just 3
stages, in fact quite a few 27 Mhz walkie talkies were built that way,
with the Regen detector doubling as the Oscillator/output stage in
transmit.

Actually, regens were rarely or never used for those applications. It was
the superregen, also patented by Howard Armstrong, that was used. It
was an extension of the regen, the addition being quenching of the detector
at frequency in the hundreds of kiloHertz range. This pulsing of th
regen detector allowed for maximum gain without the instability of the
regen going in and out of oscillation. It also results in a much wider
bandwidth. Note that the superregen is promoted for reception of FM, though
in its case it is slope detection.

Michael