[R-390] Synchronous AM Detector Kit

Thu, 24 Jul 2003 22:28:59 -0700

This technique is sometimes called "quasi-synchronous" detection. It works
just fine as long as the carrier doesn't fade out. Using a PLL is generally
preferred because it will "coast" over a momentary fade of the carrier.

The 2001 ARRL Handbook discusses this, starting on page 15.30. There is a
circuit there that allows you to switch between synchronous and
quasi-synchronous detection. It uses a chip that is normally used for FM
reception, so it has a square-wave limiter output that can be used to drive
the detector.

I haven't built that particular circuit, so I don't know how well it works,
but I enjoyed reading the article.

James A. (Andy) Moorer
www.jamminpower.com

----- Original Message ----- 
From: "Joe Reda" <[email protected]>
To: <[email protected]>
Sent: Thursday, July 24, 2003 9:59 PM
Subject: Re: [R-390] Synchronous AM Detector Kit

> At 07:59 AM 7/24/2003 -0700, Dennis L. Wade wrote:
>
> >         And for those of us who are thinking about what path to get
there on
> >(excuse the extended metaphor), anyone have any/know of any good
> >designs to homebrew?
>
>
> I found this one:
>
> http://www.radio-electronics.com/info/receivers/sync_det.htm
>
> I'd be curious to know what y 'all think of this.  I'd always wondered if
> you could send the signal
> through a limiter or two to surpress the modulation, and then use that as
> your input to the mixer or
> product detector and so achieve sync detection.  This idea (near the
bottom
> of the page) seems
> to be just that.
>
> What would you use for the limiter?  FM-type limiter circuits, such as
> those that use 6AU6s beloved of
> so many receiver designers?
>
>
> Joe W9TXU
>
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