HF SQUELCH (WAS Re: [Premium-Rx] Simple clean audio amp)

[k0dan]

Hi Tim...

Back in the early 80's the was a circuit (QST??? 73???) for a 2-channel SSB
"smart squelch". Sorry, I don't have the name/author/date anymore, but I did
build one in those days which I used with some success with a Drake R7 and
51S1, and it was sold when those radios were sold. Perhaps searching the
ARRL site might turn it up.

The problem, however, with any squelch I've ever used on HF, is that they
all get fooled by static crashes, heterodynes, splatter, etc. They DO work
better than riding the RF and audio gain, but they do false, and if you're
listening to (or recording) a bunch of utility channels, it can get pretty
annoying. This is especially so when a broadband lightning strike opens up
ALL your receivers simultaneously, or when a "sweeper" signal sets them off
one by one!

Good luck and 73

Dan
(K0DAN)

>
> Here's a slightly different question:
>
> Say I've got 3 or 4 receivers, each tuned to sideband voice utility
> HF frequencies. I want to be able to monitor these frequencies
> but don't want to listen to the audio unless there's a signal
> present. This implies some kind of squelching ability. Radios are
> not identical but generally have AGC level out or IF out ability
> (actual levels vary from radio to radio.) Is there a "common" solution
> to this problem? I look at say old WJ price lists and see squelch as
> an extra-cost option, but I'm not about to pay those kinds of prices :-).
>
> With some radios I can turn AGC on and turn the RF gain down to the
> point where background static isn't objectionable, and then when a
> signal comes in the AGC takes over. But... AGC on my WJ-8716's doesn't
> work this way! (Is it supposed to? If I turn on AGC I have no manual
> RF gain control, and if I turn on RF gain control I have no AGC. This
> is different than my other receivers.)
>
> Tim.