[Elecraft] APF For K3: progress report

[The Smiths]

That's it Ron, it's very much like you just described, now add a Q-Multiplier into that equation and you're there....
 
> From: ron at cobi.biz
> To: elecraft at mailman.qth.net
> Date: Wed, 27 Oct 2010 09:33:19 -0700
> Subject: Re: [Elecraft] APF For K3: progress report
> 
> The concept reminds me most of the very popular 1940's homebrew project the
> "Selectoject" (QST November 1947). Operating at audio, it featured a
> two-stage constant-output phase shifting amplifier the provided a variable
> frequency response from wide to razor sharp tunable across a 300 to 6000 Hz
> range as either a variable amplitude peak or a variable amplitude notch.
> It's actually a very simple circuit involving only three stages.
> 
> Ron AC7AC 
> 
> -----Original Message-----
> At 10:08 PM 26/10/10, you wrote:
> >and APF should peak a portion of that IF area that I choose (like a 
> >manual Notch filter does, but reverse)... Not move it around. 3 
> >different things here... Does it make more sense to you?
> >
> Like the old Heathkit Q multiplier, QF-1, peak or null option?
> 
> John
> k7up 
> 
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