[Hammarlund] Audio driven AGC.

[Carl]

Ive used audio derived AGC in simple SS QRP CW xcvrs that I sold in the past 
and it was OK for cheap and dirty single conversion superhets using various 
high IF's and 4 pole el cheapo xtal filters. Put the rigs on the stacked 
yagis and it thumped badly but 99% of QRPers wouldnt be caught with a real 
antenna. Amazing how well 5W worked into 16 elements on 20, 15 and 8el on 
40.

I sorta miss those antennas but not all the work.

Carl



----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: <Hammarlund at mailman.qth.net>
Sent: Sunday, May 15, 2011 4:26 PM
Subject: Re: [Hammarlund] Audio driven AGC.


> 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
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