"Bob G. Mahrenholz" wrote in message
...
Hi Tom, I was waiting for a thunderstorm so I could answer your question.
We
finally got one.

Great!

You get maximum audio in the center of the passband as long as the
regenerated
carrier is in phase with the original carrier (suppressed or not). With
the RD
it is in phase.

I get minimum audio near the centre. It's hard to tell where centre is with
50Hz steps. Tried reversing phase of feedback loop and got no oscillation,
no audio. I'm wondering whether a phase shift network might be needed in the
connection of the feedback loop to the product detector base. In Olberg's
10.7MHz version (hr 78/10), he describes a phase shift network on the input
signal to the product detector. The unshifted signal also feeds the biased
half-wave rectifier/reciprocating switch, as it does in the original
version, which lacks the phase-shifted input to the PD.

It's hard to tell what lock range I get since I have a DDS local
oscillator that
only tines in 10kHz steps. I believe that since my RD uses a xtal, the
lock
range would be in the ballpark of a hundred cycles.

As far as noise rejection, I also have an envelope detector in my receiver
and I
can switch between it and the RD. I cannot tell any improvement on static
crashes. I tried my electric shaver as a noise source and the RD may have
had
slightly less noise - but not enough difference to write home about.

That's what I get with my RD variant, too.

Do you hear heterodynes with your RD as you tune between stations and
approach lock? In your e-mail you indicate that you hear only white noise in
the absence of signal.


Bob

73, Tom