"Jimmy" wrote in message
m...
"Larry Gagnon" wrote in message
...
On Wed, 14 Apr 2004 06:41:32 -0500, H. Adam Stevens, NQ5H

wrote:
"Rick Frazier" wrote in message
...
I've just received a 5BTV, 5 band trap vertical (75-10M...

I am planning on mounting it on the peak, near the center of a rather
large metal roof. ...

.... mount it in the center of the roof and run 4 wires from the antenna
to
the corners of the roof bonding the wire to each metal panel it crosses.
One
problem with doing this is that bad connections with adjacent panels could
cause noise on recption and intermitent changes in tunning during
transmit.
Just be aware of what you may have to do to fix some strange intermittent
problems.



I agree that any intermittent contacts in the roof metal CAN make noise.
Even if the wire is routed as suggested. Receive is covered above... During
transmit there are two effects to watch for.



Any noise caused by bad connections in the wind WILL *modulate*
your transmitter with the same noise. Most likely, this won't cause a
problem for you except to other radios close by. However, the frequency
range can be extensive. On Apollo communication ships the HF transmitters
caused interference to the on-board *radars* because of the junk caused by
the deck railing chain links. Whatever the noise spectrum looks like, this
can cause an AM on your signal with the same shape sidebands. Because your
transmitter is right there and part of the antenna current is flowing in the
roof, the effect can be rather strong. On sideband I think this could sound
like splatter. Bottom line, I think is increased possibility of TVI or BCI
for the nearest neighbors.





The other is increased ability to make Intermodulation (IM). This
should only be a problem if you have two transmitters operating. This is
the sum / difference and 2A-B type of IM caused by partly rectifying
junctions in the corroded metal.



--
Steve N, K,9;d, c. i My email has no u's.