"Steve N." wrote in message
...


snip

Another concern (though I have no experience with roofs, just autos) is
the
intermitent contact (as opposed to a rectifying junction, as Richard
points
out) that is possible. If there are joints that can make and break, say
in
the wind, you may have noise generated. Chain-link fences would be
susceptable to this as well. Wether or not it produces noise in your
receiver, I would think, is rather unlikely, unless you were somewhere
near
a broadcast station or another ham for reasons described next.

It's mostly a problem if you are running two or more rigs at the same
time. Your 2M packet rig could interfere with your 2M ragchew.

The Navy, for whom I work, bonds (or isolates) everything topside for
exactly the reason you stated. The intermittent contacts are noise
generators. The tools for detecting some troublesome items are a rubber
mallet and a pair of handhelds. One guy in radio transmits a carrier,
while listening on a nearby freq. If he hears anything, he grabs his
handheld and barks, "What was that you just tapped on?" Primitive but
functional. Every spark, no matter how small, is an RF generator. Chains
are awful. We hate chains.