[R-390] R-390 AProduct Detector

[n4buq at knology.net]

On Thu, 22 Mar 2007 08:10:12 -0400, Mark Huss <mhuss1 at bellatlantic.net> 
wrote :

> There are several available, depending on how much modification you want 
> to do. The limitation of the R-390 and R-390A for high-quality SSB 
> reception are in two areas. First is that the BFO injection level is too 
> low. The second is that the AGC is not optimized for SSB. Paul Lee was 
> probably the first to address this. It involves adding a switch, 
> replacing a tube, and some extensive wiring.
> 
> The second, and probably most popular is the ‘Lankford’ mod. Developed 
> incrementally by several people, it does not involve extensive 
> re-wiring, and addresses both the BFO Injection issue and the AGC issue.
> 
> A third one is a little black-box unit that a few R-390A's were fitted 
> with. The wiring is unknown to me (anybody out there know?), but it 
> fitted behind the front panel, and provided fixed BFO and, possibility a 
> detector and AGC.
> 
> A forth one is to add a separate SSB detector/BFO at the IF Out. Several 
> Mil-Surplus detectors do this, as well as the Hammarlund HC-10. The 
> latter has the advantage of providing notch filters and bandwidth 
> filters, though it is expensive at about $300.
> 
> The latter option just got a lot cheaper if you have access to a 
> reasonably fast PC. A lot of Hams are playing with a little device 
> called a SoftRock. What this is is a IQ mixer/Detector that feeds a 
> wideband (96 kHz) signal to your sound card. Designed originally as a 
> direct conversion receiver for the HAM bands, several have experimented 
> with it as an IF detector. At about $20 per kit (and there is one 
> designed for 455 kHz), you can connect it to either the IF Input, or the 
> back panel IF Output through an attenuator. The result is a detector 
> that with the help of your PC will do AM, CW, USB, LSB, ISB, FM, and 
> about a thousand filter combinations, including notching. Add a diode 
> and buffer circuit, and you can generate AVC to feed the R-390.
> 
> I have documentation for all the above.
> 

I have one of the PD1 outboard SS detectors that connects to the IF 
output.  It works fine too.  I wonder if they still make these?  I didn't 
find them with a web search.

Considering selling mine because I just don't use it.  I can listen to SSB 
by fiddling with the BFO easily enough.

Barry - N4BUQ