On Thu, 19 Jul 2012 06:56:18 -0700 (PDT), klem kedidelhopper
wrote:

Never thought of using Romex for RF. It would indeed be interesting to
see what it's characteristic impedance would be at different
frequencies though.

Nope. It's quite constant. As I vaguely recall (and can't find my
notes), it's about 110 ohms between outside conductors for 14-2 NM-B.
There's nothing in the dielectric and insulation to absorb power, so
the impedance is going to be constant up through UHF frequencies.
However, the insulation breakdown voltage is only about 600V making
Romex rather useless for high power RF.

The big problem is what to do with the "extra" ground wire in 12-2
cable. Grounding or floating the extra ground wire allegedly didn't
seem to do anything, but I'm suspicious.

I haven't tried to design an antenna that would take advantage of this
ground wire. Perhaps a motorized yagi that uses the feed line to
supply power. With all that copper, the IR losses will be small.

Hint:
LMR-400 about $0.80/ft
450 ohm ladder line about $0.44/ft
14-2 Romex about $0.30/ft
RG-8/u about $0.17/ft

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