Cadiscase wrote:

The noise I [most] want to eliminate is the HISS when you receive a
weaker signal.

There isn't a lot out there to do that. There is stuff in the professional
audio world for doing that, but it's either based on a desktop computer or
it's expensive.

Most of these work by breaking the signal up into multiple frequency bands
and gating them individually.

The hetrodyne can also be a problem, but the slot can do some good,.

Slot?

I got the Hammarlund because I wanted the full quality sound on AM.
I will have to except some distortion when I use a DSP unit.
The CLRSpkr DSP is a reasonable unit to use I think.

It's more designed for weak signal SSB work, but try it. In general, I
find most of the gating systems sold for communications to be really
unpleasant for long-term listening.

I would like to eliminate or decrease the fading effect by a better
AVC.

I think the problem is the ionosphere, not the AVC. You can make the AVC
respond faster if you want, but then flutter becomes even more annoying.
Anything that rides the signal is going to cause changes in the noise floor
as it does so.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."