N9NEO wrote:
Greetings,

I have just got a sony ICF sw7600GR and it is a very nice radio. The
sync detector seems to take care of a lot of the distortion, but the
audio continues fading in and out and is quite annoying. Could the
fading be mitigated to any extent by using another stage of agc? I am
going to be doing some experiments with the 455kc if out on my Red Sun
RP2100 whenever it gets here. Detectors, filters, SSB, etc... I thought
that along with other experiments I might want to try some outboard
agc.

regards,
NEO

AGC systems don't lend themselves to easy modification.

There are many issues, attack time and release time, are the two most
significant.

Too fast the audio gets "chopy", too slow not enough effect.

I think I can say that I really understand the Kenwood R2000. And while
I have
tried several "improved" AGC designs, none made enough difference to be
worth mentioning.

The DX398 has some published modifications that you may want to track
down.
The main effect as I recall was to slow the release time. The DX398's
AGC
is a tad too fast.

Good luck and let us know how it works.

Synch detectors can mitigate the some of the effects caused by fading.
But in my experience are not the "do all- end all" that I had hoped.

At this point I have decided to concentrate on improving my antenna
to get the most signal and as little noise as possible. A much better
pay off for the energy required.

Terry