Rob Sherwood was the Engineer in charge at KOA Radio 850 here in
Colorado a 50kW station for many years. I got to visit the Transmitter
site once. Quite impressive tour!
W0MU
On 10/28/2016 10:18 AM, Bob K6UJ wrote:
Rob,
Kevin Kidd of AM Ground Systems could learn from us mere amateurs.
You don't necessarily need to "spend the money" and use copper mesh.
Jim mentioned Rob Sherwood's contribution of using galvanized ground
screen. I used his
ground screen system he presented and had great results. Still intact
when I took it up.
I had the four sections of galvanized mesh extending out in four
directions and used it for years until recently when I went to
elevated radials about 12 feet above the ground. As Jim stated with
the chemical makeup of our soil at any given QTH it may work in one
location and not another. Its not very expensive and worth trying. In
my case it worked well. Your premise that we should not use the
galvanized mesh cannot be regarded as universally valid. It is a good
option to "try" at our individual stations. Certainly more cost
effective than copper mesh.............
Bob
K6UJ
On 10/28/16 3:42 AM, Rob Atkinson wrote:
Some pretty sharp engineers disagree with this advice. Rob Sherwood,
NC0B, first published on the usefulness of galvanized ground screen
in 1977, and talked about it in >presentations in the Dayton Antenna
Forum in 2008 and 2009. Rob is best known for his work on
quantifying the receive performance of modern HF rigs. Like anything
making >contact with the chemical makeup of soil and local moisture
at any given QTH, materials that work in one location may not work
in another.
You can go to all the trouble of putting down "mesh" and risk having
to do it all over again since that is a material and product not
intended to be in contact with the ground.
Or you can spend the money and do it right from the get-go, except
that in professional installations, copper mesh or screen, is only
used with voltage fed towers. For most ham situations the tower base
is a current maximum, i.e. a 90 degree radiator base fed, and for that
a radial ring and ground system made up of radiators is fine.
Who are all these "sharp engineers?" Kevin Kidd of AM Ground Systems
Inc. has probably done more professional AM tower ground system
installations and re-builds across the U.S. then all of your "sharp
engineers" combined.
There's nothing wrong with being a cheap ham at the hamfest, but the
ground system is one area where cheap just buys trouble within a year
or even a few months.
73
Rob
K5UJ
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