[Hammarlund] Audio driven AGC.

[Kenneth G. Gordon]

On 15 Apr 2011 at 12:43, Richard Knoppow wrote:

>      There is a method of generating AVC for SSB from the 
> recovered audio. Its rectified and the resulting DC voltage 
> is used for AVC.

Yes. It was often called "Audio-derived AGC", and was often used in simpler 
receivers.

> The system works quite well.

I never liked it because by the time the audio has risen sufficiently to act as 
AGC, the spike has already passed through the IF stages. It is simply too 
slow. It was a favorite circuit for Direct Conversion receivers.

> I remember at 
> least one article describing such a system although I don't 
> remember where it was now.

Yes. In fact, there have been several in various magazines over quite a long 
period of time.

However, I think the one that Ken N5CM is talking about was a circuit in 
which the audio output, after proper "manipulation", was fed back into the 
standard IF or detector-derived AGC to modify the way it worked. I vaguely 
remember one such article from at least 40 years ago, but the details are 
simply not in my memory banks any longer.

Ken W7EKB