"J. C. Mc Laughlin" wrote in message
.. .
Dear Group: I expect to craft a common-mode choke for 50 ohm coax that
works from 1.8 to at least 7 MHz using Type 31 (Fair-Rite) core material.
Use of any Fe material in coax at the lower HF frequencies is undesired -
no center conductors containing steel. Such coax should be able to
tolerate being bent with a small radius to facilitate multiple turns
through the core - no foam dielectric.

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. . . .

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

Thanks. 73, Mac N8TT


Look he
http://www.thewireman.com/coaxp.html

They list rg400 at about $ 2 per foot.

They may also have something you need for the choke.