[Collins] 75S3B info

[Gerald]

On Wed, 2005-06-22 at 18:34 -0500, Don and Diana Cunningham wrote:
> I just got a very nice 75S3B in a S3 line today (73S3B, 32S3, 312B4, 516F2, 
> 30L1).  I am in the process of looking it over for obvious problems before 
> "smoke testing", hi.  Under the filter cover on top of the chassis, I found 
> some foam packing around the filter that is doing some serious 
> decomposition, to the point that it will crumble mercilessly when touched!! 
> Any reason to try to find/make a replacement foam for this??  If so, anyone 
> have a spare before I start looking for some foam rubber to cut up?
> Tks,
> Don, WB5HAK 

Before the filter shield (which reduces the magnetically induced hum
modulated noise at the detector using the plastic cased filter) there
was a strap holding the SSB filter down. I discovered that noise on my
own and used a bit of mumetal right on the filter that fit under the
strap. So the foam in the shield is just to hold the filters in their
sockets, but it won't help with the 300 Hz crystal filter, its too tall
for the strap or the cover, but it doesn't seem to have the hum induced
noise problem.

I think having some foam to hold the filter down if the receiver is ever
going to move around would be a good idea.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer