Good information, (below), thanks. On the issue of availability,
though, I have to wonder why they would NOT be available for sale?
Obviously, certain manufacturers of the multitude of ham-stick type
antennas use them. There must be a large scale source, somewhere!

Ed




As a modification to this, since you can stand 1/2 inch thread, how
about using a 1/2 inch bolt and brazing or silver soldering some 1/2
inch ID tube over it? Not only will this be easier than trying to
center the 3/8 and potentially stronger than epoxy, but it would keep
that RF continuity.

This is the sort of part that's expensive to turn out as a one-off
part, but very easy to manufacture on an NC lathe -- even a cam-driven
automatic screw machine would handle this with ease. Because of this
I suspect that there aren't any on the open market; rather a
manufacturer would just send drawings to their favorite screw machine
place to have them made 10000 at a time.

It's also the sort of part that's fun to make in limited quantity --
it looks pretty, you get to practice your threading, yet its not too
critical. So you might want to take up Paul's offer, perhaps with a
nice drawing. Just don't ask him to make too many.