[R-390] Best approach for SSB mod on R-390A

[2002tii]

Cecil wrote:

>I would love to hear from anyone that might own some of these 
>outboard devices...I know there were several of the earlier PD-1's 
>out there and a few SE-3's as well....

I have an SE-3 and frankly, in my view, it's not worth the time it 
would take to toss it into the trash.  Anyone who has used a properly 
designed synchronous detector would just laugh at it.  IMO, the 
esteem in which it seems to be held in some quarters shows how few 
hams and SWLs have used a properly designed synchronous detector.

The SE-3 oscillator is not temperature compensated, and it drifts 
beyond the ability of the frequency trim capacitor to center it as 
the temperature changes.  I had to drill a hole in the top cover 
above the tuning coil and leave a tuning tool poking out the top to 
tweak it.  The capture and lock-in ranges and behaviors were also not 
well chosen, necessitating that the user manually "guide" the PLL 
into lock.  All in all, a very poor effort, IMO.  PLL design is just 
not that difficult.

NOTE: the above comments pertain primarily to using an SE-3 as an AM 
synchronous detector.  It's OK as a BFO/product detector, but far 
from state of the art even for that use.  The SE-3 does not have IF 
filtering or AGC -- it depends on the host radio for those functions.

For anyone interested in constructing a properly working synchronous 
detector, here are three of the many references you will find through 
a web search:

http://www.premium-rx.org/ref/amsynchronous.pdf

http://webpages.charter.net/wa1sov/technical/sync_det.html

http://www.arrl.org/tis/info/pdf/9307028.pdf

Best regards,

Don