[Hammarlund] Super Pro 210-SX rides again

[Bob Young]

You know I get ER and I had read that article last week while I was half 
asleep and forgot about it, working too much I think. There's a nice SP-200 
X model on ebay right now, looks good and supposedly works good with power 
supply. BTW thanks for the encouragement and I'm going to try the De-oxit 
next day off I have (Friday) and poke around a little more,

Bob



----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at verizon.net>
To: "Bob Young" <youngbob53 at msn.com>
Cc: <Hammarlund at mailman.qth.net>
Sent: Monday, April 17, 2006 1:47 PM
Subject: Re: [Hammarlund] Super Pro 210-SX rides again


> On 17 Apr 2006 at 13:26, Bob Young wrote:
>
> > realize it will still need to be recapped though. Any ideas on the
> > dead band?
>
> First of all, I must give you an "Attaboy". Ya done good, Kid. :-)
>
> Secondly, you might try DeOxit-ing the bandswitch contacts, but do
> it SPARINGLY. I use a toothpick, or, at most a cotton swab, on
> each contact. Another advantage of doing it this way is that it will
> enable you to check each switch contact for other problems.
>
> Too much DeOxit-5 (or Cramoline, which is a stronger version) can
> cause phenolic bandswitch insulators to swell.
>
> You could also have one or more bad coils.
>
> BTW, as I said before, Electric Radio magazine (www.ermag.com)
> has an article on the restoration of an SP-200 or 210 in the latest
> issue.
>
> Although the author states that his (and other) SP-200s "never stop
> drifting", I disagree.
>
> I had a BC-779, which is the military version (I think) of the SP-200.
> I converted 1/2 of the 6N7 noise limiter tube to a triode product
> detector, copied from my Heathkit SB-101, and used the BC-779
> for RTTY for several years.
>
> I mounted it in a rack, and never turned it off. After about a week of
> being on, it stopped drifting in one direction, and started drifting
> VERY slowly back and forth a few cycles. It was actually extremely
> pleasant to listen to, and made no apparent difference in how my
> RTTY converter worked. I also used it on CW.
>
> The triode product detector made a truly tremendous difference in
> the apparent sensitivity of the receiver. After installing the triode
> product detector, my BC-779 was the quietest receiver in the
> shack. It exhibited extremely low internally generated noise,
> probably due to its two RF amp stages.
>
> I was extremely fond of that receiver, and am sorry that I don't still
> have it, but that was over 40 years ago now.
>
> Maybe someday, after I have retired, I will try to find another one
> just to see if what I remember about it is accurate.
>
> Ken W7EKB
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