[BULK] - [TowerTalk] RG-11 Source?

[Steve Katz]

That's not entirely true. Ever try to make a vhf or uhf duplexer on a 
two way radio system work with only single shield interconnects on the 
cavities? Especially with a close spaced system. You will never get the 
isolation to stay put. Move a cable around and the isolation changes. 
You don't have that problem with double shielded cables.

73
Gary  k4FMX


::Gary, I agree with you, and that mirrors my experiences, too.  And
actually, when I was with Comcast, we did a great deal of experimenting with
coaxial cables for distribution and the quad shielded cables which led to
the common RG6-Quad that's used everywhere today, absolutely performed
better in a variety of ways.  If not, nobody'd bother paying extra to buy
it.  One great test was to run the cable overground with a normally
conducted signal and then bombard the cable with 10v/m interference (same
signal, phase shifted) to see the effect on the demodulated video.  This was
with double-crimp F connectors, perfectly installed, in repeated testing
using many different cables.  We could make ghosts occur any old time we
wanted to with RG59/U, RG6/U, double-shielded braided cables and
double-shielded braid over foil cables.  It wasn't until we tried quad
shielded cables (foil/braid/foil/braid) that we just plain couldn't create
ghosts at any interference level we could generate.  I can't think of any
common amateur applications where any of this would matter, though....
-WB2WIK/6