[R-390] Synchronous AM Reception

Tue, 26 Mar 2002 12:06:37 -0500

Al,

I believe that this was the one in the '96 handbook.  I think that's the
year that I have that I saw it in.  I should have looked last night but
didn't.

I'm interested as to why yours did not work.  As it is similar to what I've
been contemplating.  If you'd like I would be willing to look at it for you
and try to figure out why it didn't work.  It could be a PCB layout problem,
or even a noise problem on the VCO in the sync detect mode.  Either way I'd
be interested in seeing your artwork for the PCB.

73's
Jim N8CAH

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Al Solway
Sent: Monday, March 25, 2002 11:14 PM
To: Jim Amos
Cc: R-390 list
Subject: Re: [R-390] Synchronous AM Reception

Jim,

I don't know if you are referring to the same circuit that is in the
1996 ARRL Handbook. From what I can understand from the circuit
description this is supposed to be a phase locked synchronous detector.
But I am not an engineer, only a tech with a few years experience. So
please don't take what I say with as the gospel as written by me.

I built this circuit about a year ago on a PCB. It did not work as
expected as a synch detector. It worked  well as a side band detector.
The audio was very good. I put the project on hold when I purchased an
R-390 non A that was entitled to my undivided attention. Let me know if
the circuit you are referring to is the same one that is in the 1996
Handbook.

I did contact the author of the article, Jukka Vermasuori, OH2GF for any
changes or updates to the article. He responded with no changes. If you
want his email address let me know.

Al VE2TAS

Jim Amos wrote:
>
> 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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