Behold, Chuck signalled from keyed 4-1000A filament:

Guys,
I remember seeing, for sale, a flat shielded cable....

Hi Chuck!

I remember that too. Not being able to find any, I have used a 6 inch
length of Acoustic Research flat speaker cable. It has a nominal Z of 100
ohms (as measured) and after wrapping it in tinfoil, that dropped to about
90.

A 6" length ain't gonna bump the impedance of the feed so bad that you'll
loose more than a fraction of a DB on RX.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca