Ok I baised the Ge detector diodes in both of my R2000s.
They require very different amount of currents.
1 is best a 0.2mA, and the other needs 3.2mA.
The audio gets much cleaner, as measured on Spectra Plus,
a great program but it's licensing system is a real PITA!.
For prior unid FSK work I had modified my sound card to
allow direct access to one set of inputs.
No caps to add problems.

Anyway on my 500KHz master RF source, with a clean modulator
I measure 20% THD on any radio with a "diode" detector at
95% symetrical modulation. By forward biasing the diodes in
the R2000 I can knock that down to less then 5%.

Great, but it screws the AGC up big time.

When connected to an antenna and received the wildly changing
levels on HF the radio just "goes nuts", clearly this changes
AGC time constants.

OK, I am now going to plan 2. Years ago when I used a R392 I
was less then pleased with the CW/SSB/FSK reception. I had
gathered the stuff to build an outboard "detector module".
This was in the early 80's and I hadn't heard of, and don't
know if it was available, Kiwas MAP, or the Sherwood SE-3 out
board detectors. I didn't know about synch detectors, but I
wanted FM-N, AM, and GOOD CW/SSB reception. I looked at several
of the links suggested and founds some fairly simple "precision
diode detectors" that look like they will solve the AM.
I still have my BFO from that never finished project, and some
hwere Ihave my PLL FM detector. I never got around to builidng
it becaue I bought my first R2000 and it was "good enough".

I am convinced that one barrier to understanding weak AM signals
is the distortion caused by the simple AM detector, the sonic
"flavoring" produced poorly choosen capacitors and the crude
AF power IC. I tried tapping the signal straight from the detetor
with a Hi-z Jfet buffer and feeding a Class A headphone amp
I built with MOS-FETS. The sound was much cleaner and I could
understand a weaker signals I generated here with a MC power
divider in reverse. The Radio is connected to the common, the
antenna to 1/2 power port, (after my nuvister splitter to provide
a "true" 50 Ohm antenna) and my HiFer beacon, greatly attenuated,
into the other 1/2 power port. I used a local 24 hour talk radio
station as the modulation source. Now the HiFer beacon does not
have the best modulator. But I could reduce the output of the
HiFer beacon to a level about 4 or 5 dB below that which I could
understand the conversation with the built in audio chain. I think
the Rec out is as clear, but after messing with this for 5 hours
I don't really trust my ears. My wife cna dig into the noise at
least another 3dB. I rode a motorcycle for 25 years and have some
hearing loss.

So my plan of attack has become:
Add a IF jfet buffer to both R2000s.
Build a better AM detector.
Complete my FM-N detector.
Use a MC1496L balanced modulator for the product detector.
Add a minimilist audio section with a "see-saw" tone control.
Build a simple 10watt low distortion MOS-FET power amp to drive
speakers, or headphones.

Now can a MC1496 be used as a synch detector?

Any suggestions other then buying a "better" receiver?

I am dead bugging an improved AM detector tonight with
video opamps. I may complete in time to post before I
go to bed in three hours.

One of the reason why I am going after weaker and weaker signals
is I have "caught all the easy stuff".

And this doesn't begin to address other local noise issues
that a friend made me aware of.....

Terry