Hi Tom, I was waiting for a thunderstorm so I could answer your question. We
finally got one.

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.

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.

Bob

Tom Holden wrote:

Bob, thanks forcoming back. I'm delighted to connect with someone who has a
RD.

Do you not get null or minimal audio at zero beat in the centre of the
passband with your authentic RD? I thought that this would be the normal
response of a product detector on symmetrical sidebands - the negative
frequency product would be antiphase of the positive frequency product.
There is no such null on a SSB with carrier signal such as CHU.

What lock range do you get? Without the 455kHz filter in the feedback loop,
I get about 400Hz. With a ceramic resonator of unknown interelectrode
capacitance, I have been trying different values of parallel inductors and
getting lock range of 100 Hz or less.

Do you find that the RD suppresses impulse noise and static crashes?

73, Tom VE3MEO

"Bob G. Mahrenholz" wrote in message
...
I have a Reciprocating Detector that I built from a kit of parts that I
purchased
from W1SNN back in 1972. I use it at 455kHz in an AM broadcast receiver to
eliminate selective fading.

The IEEE Comm paper by Badessa lists the patent on the RD that you can
look up.
Also if you get a null in the center of the lock range you may be locking
90
degrees out of phase with the carrier.

Bob K4QQK

Hi Tom, I was waiting for a thunderstorm so I could answer your question. We
finally got one.

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.

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.

Bob

Tom Holden wrote:

Bob, thanks forcoming back. I'm delighted to connect with someone who has a
RD.

Do you not get null or minimal audio at zero beat in the centre of the
passband with your authentic RD? I thought that this would be the normal
response of a product detector on symmetrical sidebands - the negative
frequency product would be antiphase of the positive frequency product.
There is no such null on a SSB with carrier signal such as CHU.

What lock range do you get? Without the 455kHz filter in the feedback loop,
I get about 400Hz. With a ceramic resonator of unknown interelectrode
capacitance, I have been trying different values of parallel inductors and
getting lock range of 100 Hz or less.

Do you find that the RD suppresses impulse noise and static crashes?

73, Tom VE3MEO

"Bob G. Mahrenholz" wrote in message
...
I have a Reciprocating Detector that I built from a kit of parts that I
purchased
from W1SNN back in 1972. I use it at 455kHz in an AM broadcast receiver to
eliminate selective fading.

The IEEE Comm paper by Badessa lists the patent on the RD that you can
look up.
Also if you get a null in the center of the lock range you may be locking
90
degrees out of phase with the carrier.

Bob K4QQK

"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

"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