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

[David Wise]

My SE-3's oscillator is very steady.
I wonder if there are good ones and bad ones.

Also, without manual controls, the detector has to
guess the operator's intentions, based on, say,
tuning rate.  I don't like machines trying to
read my mind, because they usually get it wrong.
For me it's better to have direct hands-on control.

My only complaints have been the lack of a noise
limiter and lack of a 5kHz notch filter in addition
to the 10kHz filter.

I've bookmarked your recommendations.
Sometime I'll build one or more and report my
experience using them vs the SE-3.  Or if anyone
local has built one, let's get get together and try
it out next to my SE-3.

Dave Wise
SWL in Hillsboro Oregon

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net] On Behalf Of 2002tii
Sent: Tuesday, December 22, 2009 5:06 PM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] Best approach for SSB mod on R-390A

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