[ARC5] OK Smart People- FM Demodulator

[Tom Dawson]

Alternate Suggestion (There's always gotta be one)



NE604AN FM IF/Demod chip.

Still available in reasonable quantities on (gasp) ebay for the 4 dollar 
range.

The AN suffix means it'll work for IF's up to over 20 Mcs, and I've used in 
on 21.4 Mcs.

It has two sections, and there's supposed to be a filter bethween them, but 
with the receiver's existing IF amplification, you probably only need the 
back end and a coil and condenser for the quadrature detector.


just a thought...

73

Tom
WB3AKD



----- Original Message ----- 
From: "David Stinson" <arc5 at ix.netcom.com>
To: "ARC-5 List" <arc5 at mailman.qth.net>
Sent: Friday, January 18, 2013 7:58 AM
Subject: [ARC5] OK Smart People- FM Demodulator


> Calling all "Smart People:"
>
> Doing some research on a "Borg Implant" FM Demodulator
> in the hopes of breathing life into many dust-gathering VHF sets.
>
> I found this interesting circuit:
>
> 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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