exray wrote:
Grumpy The Mule wrote:
Well that's sad. I doubt it's nylon which was invented in 1938,
maybe phenolic? Wood filled phenolic which swells... ugh!
Maybe you can rinse it with solvent then dry it out so it will
shrink back to nominal dimensions. The rest of it is constructed
of isolantite and brass which solvents won't hurt.

Could be phenolic but it really seems like a plastic of sorts. Hard to
tell. The front bushing is where it got tight and there's no easy way
to get it out for a thorough cleaning.

-Bill
That is a VERY weird capacitor. First of all it tunes through 270
degrees of rotation using a unique shape of rotor plate, stator plates
are triangular. Second weird thing is that the shaft bearings are
insulated from the frame, the rotor is grounded at a single point, a
flexible conductor running though the hollow shaft and grounded at the
rear of the rotor. I have a single gang version of that capacitor that
was 'featured' in the one tube regenerative receiver from the A. P.
Morgan 'Boy Electrician' book from the 50's. National did make scales
for their velvet vernier dials that went through 270 degrees of rotation
for use with these capacitors.