[R-390] Synchronous AM Reception

Mon, 25 Mar 2002 15:58:14 -0500

There was also a circuit in the 1999? handbook that was both a synchrous
detector and external BFO / product detector.  It did use a 455KHz IF input
as well.

This circuit was nice in that it also provided for synchrodyne demodulation.
This is a version of synchronous detection that amplifies and limits the
carrier before applying to the product detector.  It does not, however,
phase lock a carrier generator to the incoming signal as true sync detection
does.  Interesting for comparison, however.

The drawback to this circuit is that some of the IC's were not as readily
available as one would like.  I'm working on a version that should be
completed some time before the 75'th B'day of my R-390A that uses NTE
available IC's.  But this project is still in the planning stages and is a
result of the following failure:

I was recently experimenting with a circuit originally published in Comm.
Quarterly based on a Motorola Stereo Demodulation chip.  It however, it not
go well. The version of chips that I received would not lock over a wide
enough range to make the circuit useful as an add on Sync Detector.

I also have a friend that was selling synchronous detector kits.  His kits
were based off of the IC used in the Sony receivers.  They worked quite
well, and provided for sideband selection of the AM signal.  They were
purely for AM demod however, and did not provide a SSB / CW product
detector.

Jim N8CAH

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Jim Brannigan
Sent: Saturday, March 23, 2002 3:39 PM
To: R-390 list
Subject: Re: [R-390] Synchronous AM Reception

Thank you for all the replies.
I also did some digging on the WEB.
Very interesting.......

73, Jim

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