On 9/2/2011 6:06 PM, Brian Machesney wrote:
>> Thanks to NI0C for reminding me that this info was presented by NC0B
>
Chicken wire or rabbit wire make an inexpensive alternative to an
expanded copper mesh ground screen. Just roll it out in multiple
directions from the tower base and tack it to the ground on top of the
grass. The grass will grow through it in a short period and it will be
invisible. that is easier than rolling up the sod for sure. The only
problem is the connection but since the actual tower is most likely
galvanized steel there isn't an issue of dissimilar metal just figuring
out how to making a convenient connection via a galvanize steel bus with
similar jumpers to the actual tower. Soldering is not possible and cad
weld is expensive. Tinned copper braid jumpers with the proper
preparation can work and galvanized steel angle brackets as well. What
you don't want are a bunch of diodes at the base of the tower which is
certain to occur with corrosion. Small jumpers made from 3/8 inch
strand guy wire are fine using small U-clamps to the screen but should
be above ground for frequent inspection.
Many know how well a HF or VHF vertical will perform on a steel roof as
compared to a poor ground. In fact the screen does not have to be out
1/4 wave as the major losses in any ground occur closest to the base of
the tower. Running a few 1/4 or less radials in the empty spaces
between screens should not hurt. With today's copper prices a chicken
wire screen may do well for you.
Herb Schoenbohm, KV4FZ
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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