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

[Tom Rauch]

> cheaper -- and it accepts the correct connectors.  There
really is a
> difference with the extra shielding -- you can see it in
much reduced
> ghosting on signals, especially in metropolitan areas
where multipath is
> abundant.  -WB2WIK/6

I don't think so Steve.

In the field or outside a lab you can't measure the signal
leakage through a single shield cable, unless the cable is
defective or really junk.

Ghosts and leakage were virtually always bad connectors and
the remaining problems were broken shields (mostly by tree
rats). I supervised engineering for a company that had
dozens and dozens of systems and headends, and was always
involved in field quality.

We had a system someone wired with some special quad shield
to prevent AM and FM BC ingress (it was next to a BC
station) and wound up just ripping out all the fancy stuff
and using a single foil cable with a single loosely woven
braid. We did that because we could get better connections
at the fittings, and that's where all the measurable ingress
was rooted.

Once a shield is several skin depths thick and has no breaks
larger than a small fraction of a wavelength, adding more
layers doesn't do a thing except help DC and low frequency
AC resistance. Sometimes at GHz frequencies the foil wrap
has resonances, and a second wrap that has integrity over
the "slot" will help. TV channels are really in a sweet spot
for not being especially critical.

Consider twin lead! It has no shield at all, and it worked
fine.

73 Tom