On Mon, 8 Oct 2012 23:34:11 -0400, "J. C. Mc Laughlin"
wrote:

One such coax appears to be the expensive RG-400. Only need a few feet.
Question: What might be a source for short lengths of RG-400? I have tried
Newark, Mouser, and the like. . . .

http://www.ebay.com/itm/230756316444
http://www.ebay.com/itm/160856544191
http://www.ebay.com/itm/380086386242

Question: What other small diameter coax uses no steel and has a solid
dielectric?

Are you looking for low triboelectric noise or low piezoelectric coax?

RG58A/U also known as "Cheapernet". The problem is that I've seen it
with both solid copper center conductor, and cheaper copper clad steel
center conductor. It also only comes in polyethylene foam dielectric.
If it's solid dielectric that you want, you're stuck with Teflon.

For RG58A/U in Teflon, there's Belden 88240:
http://www.belden.com/techdatas/english/88240.pdf
which also has a solid copper center conductor.

There's a potential problem with using RG400 or any Teflon dielectric
coax in a torroidal balun. It might cold flow. The center conductor
might shove its way through the Teflon dielectric and short to the
shield braid. I've only seen this in smaller diameter RG188 Teflon
coax, but it might happen with RG400. I don't really know if it will
be a problem, but methinks you should be aware of the possibility.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558