[ARC5] [BoatAnchors] OK Smart People- FM Demodulator

[Bob Macklin]

How about using a RATIO DETECTOR like old TV sets did.

The SA-614 family of FM Chips uses a ratio detector.

If you don't mind using solid state you could use an outboard SA-614 to 
recover the FM audio.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- 
From: "Arden Allen" <gumbear at pacbell.net>
To: "David Stinson" <arc5 at ix.netcom.com>; "ARC-5 List" 
<arc5 at mailman.qth.net>
Sent: Friday, January 18, 2013 9:15 AM
Subject: Re: [ARC5] [BoatAnchors] OK Smart People- FM Demodulator


> Dave, if L1-C5 was resonant at the frequency you want to demodulate the
> phase shift would be zero degrees, not 90 degrees.  You could think of a
> quadrature detector as functioning something like slope FM demodulation 
> with
> an AM receiver where you tune the signal to the sloping skirt of the IF
> bandpass where frequency variation will produce amplitude variation to the
> AM detector.
>
> Arden Allen
> KB6NAX
>
> If you get to thinking you're a person of
> some influence, try ordering somebody
> else's dog around.  -Will Rogers
>
>> ....
> ..
> http://jaunty-electronics.com/blog/2012/08/no-tune-ne602-ne612-fm-demodulator/
>
> It's supposed to work between 420-500 KC.
> I'm hoping to "tweak" something like this for 15 MC,
> since the NE602 / NE612 will work well into UHF.
> What puzzles me is the tank circuit L1 / C5.
> 820 uH and 100 pF resonate at 555 KC.
> Is that right?  And if so, what resonant freq would
> one use to get the thing to work at 15 MC?
>
> 73 DE Dave AB5S
>
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