[R-390] R-390 SSB Product Detector mods?? Not A

[Dan Merz]

Ed,  my memory is poor.  You reminded me how much help you gave me when I
was trying to build the AI2Q unit and you provided a nice description and
schematic in a Word document of the unit that was a precursor to his crystal
controlled unit.  Likewise,  I've been very happy with the result.  I bought
a couple of the r392 bfo pto's and used one in replacing the bfo in a Mackay
3010 and haven't gotten around to putting the other in a ssb detector but's
it's in the back of my mind.  We moved about a year ago and only two days
ago did I get around to hooking up the 390 with the outboard ssb detector -
it and the radio worked just fine after the rest.    best regards,  Dan. 

-----Original Message-----
From: DJED1 at aol.com [mailto:DJED1 at aol.com] 
Sent: Tuesday, July 22, 2008 8:43 AM
To: mdmerz at verizon.net; k2lrc at k2lrc.com; r-390 at mailman.qth.net
Subject: Re: [R-390] R-390 SSB Product Detector mods?? Not A

Peter and list
I'd certainly recommend the AI2Q unit if you're up to building it.   Alex 
based it on my design using a capacitor-tuned BFO.  I've been using  mine
for several years and have done a couple of modifications.  I'm  happiest
with the last, which uses a R-392 BFO coil as the oscillator.  I  checked
the stability and it's just as good as the original R-390A  oscillator.
I modified my circuit to use Alex's crystal BFO several years ago, but I
like the tunable better.  It depends on your preference- the crystal is
easier to use-just flip the switch.  However, my  crystal  frequencies are a
bit off for the correct edge of the 2 Kc filter so I lose the  lows on one
sideband, and are obviously not at the edge of the 4 Kc  filter.  With the
tunable BFO, you can set it exactly to the edge of the  filter.  
I had two objectives when I designed the SSB adapter, to make it work
without and mods to the radio, and to provide both a product detector and a
fast attack AVC.  It works great and will handle very strong signals.  The
AVC is not quite as flat as my R-4C, but the original AVC on the R-390A is
not  very flat either.  
Unfortunately, this is not available except as a build-it-yourself.   
However, I can provide help if you have problems.
Ed  W2EMN  (formerly WB2LHI)



**************Get fantasy football with free live scoring. Sign up for 
FanHouse Fantasy Football today.      
(http://www.fanhouse.com/fantasyaffair?ncid=aolspr00050000000020)