dxAce wrote:

I'm not an expert on this by any means but as I rcall we went
through the Schottky diode craze about 20 years or so and
for the most part it seemed to be bunk.

Perhaps one of our resident techs might weigh in on this.

dxAce
Michigan
USA
---------------------------
I am hoping to improve the AM detecton in the R2000. I have done some
experimenting and decided that changing the caps was worthwhile. I
tapped straight off the detector with a DC coupled hi-Z FET, fed it
to my classs A servo heaphone amplifier and switched back and forth
between the my buffer and the Rec out, and then the input to the power
amp IC. This porved somehting I already knew, but IC audio amps
suck. Lots of crossover distortion. By taking my audio upstream
I was able to understand weak singals. As opposed to just telling
something was there. I using my HiFer beacon feeding a attenuator
and using my MC power divider to feed my antenna and the RF
to the R2000s. This allowed me to nearly duplicate real world
conditions with QRN/M. I used a local 24 hour talk radio station,
for my modulation source. Pulled it from my DX398 tape out.

I am going to be very busy changing caps for the next month.

I have decided that some of the low level "Grunge" that I
wrote off to PLL phase noise is in fact distortion caused by the
caps, and the nasty cross over distorion in the audio power IC.
I am going to replace that stage with a much better design.

While I would love to buy a new, or better used receiver, I have
to stay within a budget, so it is either modify or accept.

Of course some people mihgt nominate me for "sows ear
to silk purse" prize of the year.

Later tonight I am going to try adding some forward bias
to the AM detector diode. Distortion is after all another form
of noise.

Terry
Terry