"Bill" wrote in message
...
Hi all,
many years ago I read a very good article on the "rusty bolt effect"
that went into great detail, even as far as warning about corroding coke
cans in the undergrowth. I now can not find my copy of this. I don't
suppose any one can point me in the direction of any good descriptions
of this? I've spent time Googling and have come up with a lot of info
but I'm still looking for something I can show to a non technical person
and hope they can understand the fundamentals.
Any ideas??????
--
Bill

I've told this B4, but... It doesn't always have to be IM. There's what I
dubbed the "screwdriver effect". Near (within 10 feet or so) a transmitting
antenna (2 Meters works great) and receiver on a nearby frequency, rub a
screwdriver, or other metal object onto another one.

The Apollo space program used ships at sea for communications. They had
high power HF equipment (many kW) which interfered with the radar systems
(multi-GHz). The deck railing chain sections used for removable sections
were found to be causing the problem. The links move with wind and ship
motion causing intermittent and noisy contacts which produced noise that
modulated the HF RF field causing sidebands up into the GHz regions.

I observed similar on early car telephones @ 150 KHz. Noisy hood, bumper or
trunk (or motorcycle seat spring) junctions caused noise that modulated the
transmitter's radiated field which extended into the Rx band and
desensitized the receiver. I developed a probe to sniff out the noise
sources and bond (make solid) the connections.
One of the local repeaters has a similar problem when it gets windy.
Everyone has scratchy noise on their signal, regardless of signal strength.
Nobody wants to climb the tower and check every other installation and bolt
for tightness or whatever...
--
Steve N, K,9;d, c. i My email has no u's.antenna installation....