"Tom Holden" wrote in message
. ..
Chris Trask wrote:
I learned by way of Google that there was a thread on
this newsgroup last Summer regarding reciprocal
detectors. I'm interested in learning what sort of
success any of have you have had with regard to noise
immunity and adjacent signal suppression.

This was probably the discussion I triggered on the Reciprocating
Detector. I had intended to migrate my proto-board version to a
more rf friendly board this Winter but still have not done so. I
have done little home brewing and even less experimentation with
detectors so can't really provide much perspective. I thought it
worked well on SSB with carrier, such as CHU, but it seemed to
null the audio at centre lock on DSB signals - as though the
sidebands were demodulated with opposite phase. Thought it might
have been a consequence of the strays on the proto-board because
I am the only one to have observed this phenomenon with the RD.

Additionally its self-oscillation frequency pulled on strong bass
modulation towards the sideband of SSB suppressed carrier - a kind
of FM distortion. It likewise was pulled by strong ICW signals.


I happened to discover a copy of the original IEEE conference paper in
my files here, and I see that the circuit requires that the input signal be
reduced to a half-wave rectified signal. The Ham Radio articles state that
it was difficult to achieve a faithful half wave signal. I know that I can
overcome this problem with my patented method of augmentation, which I have
used to make very linear 1W HF/VHF/UHF amplifiers. Another problem is that
the circuit needs to be balanced, and in the Ham Radio articles this need is
not faithfully implemented. Looks like there's lots of room for
improvement.

Chris