On Mon,11/7/2016 6:23 PM, David Voit wrote:
I
have an end fed wire with a 9:1 balun with about 15 feet of coax to the
banun and 90 feet of wire with no counterpoise.
No counterpoise is your problem. RF current MUST have a return. If we
don't provide a good return path, mother nature will find one, like the
wiring in our home. ANY end fed wire without a counterpoise is only half
of an antenna. A connection to earth is NOT a return -- the earth is big
resistor! Indeed, a connection to earth does NOTHING useful for a
transmit antenna.
However -- security products and systems are notorious for having
TERRIBLE RF immunity. Virtually any wired security system is likely to
have problems with RF, regardless of how it is radiated or conducted.
And yes, problems like this CAN be the result of the antenna itself
radiating -- that's what it's supposed to do -- but those devices SHOULD
be built to reject RF.
For some practical ideas about counterpoises, check out the slides for a
talk I did at Pacificon several years ago and for several ham clubs
about how to get on 160M from small lots. It's mostly about vertical
antennas and counterpoises. http://k9yc.com/160MPacificon.pdf
73, Jim K9YC
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