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

The sync' is doing what it's designed for by reducing the distortion
caused by selective fading, but you need a longer time constant (release
time) for the AGC, to help smooth out the fading. You could lengthen the
time constant of the AGC circuit in the 7600GR but then it wouldn't work
well for other conditions where a shorter time constant is needed. This
is why a good table-top receiver has more than one AGC rate, which can
be selected by the user. The AGC in the Drake-R8 series uses a decay
rate of 300-ms for the fast setting and a much longer rate of about
2-seconds in the slow mode. The latter really aides in reducing the
effects of rapid fading.