[R-390] SSB / Sync AM Detector

[Tom Frobase]

I was interested in finding a solution that would work with the 455KHz
output of the 390 radio.  I found this article in an old ARRL publication
and built it a few months ago.  The parts were fairly easy to find, I
crossed the inductor to a Coilcraft part, the 4:1 50 ohm transformer I use
on my loop amplifier product..  The bonus was the synchronous detector.  I
added a LM386 later to drive a small speaker.  It is all on the revised
circuit board.

The circuit board layout was a quick one, but it seems to be effective.  If
anyone is interested in building your own, send me a note, I can supply the
circuit boards and some hints on where to find the parts.  I built the
prototype in a Ten-Tek case but thought a 1 or 2 U rack box might be a
better choice.

Pictures are located here http://www.kitparts.com/390_Detector/

original article
http://www.arrl.org/files/file/Technology/tis/info/pdf/9307028.pdf

 Tom, N3LLL