[Hammarlund] Super Pro 210-SX rides again

[Kenneth G. Gordon]

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