Back in the 80's at another QTH I used a ground screen at the base of a
100' shunt fed tower. It consisted of 5 rolls of 2x4" mesh galvanized and
plastic coated rabbit fencing. The rolls were 50' long by 4' wide and
were laid out on the ground as spokes.
At about every 6" or so I bonded the overlaps with # 16 tinned buss wire.
A 150 W solder iron vaporized the plastic and the galvanizing took the
solder extremely well. All exposed joints were sprayed with automotive
undercoating. The base of the tower legs were bonded with a ring of #6
bare copper and I had at least 50 wires soldered from the ring to the
mesh.
At the far end of the mesh I soldered on radial wires that extended to
the property or house limits. Some were only 40-50' and others were up to
200' long.
Where the mesh covered the lawn I held it flat with some U shaped wires
driven into the ground and covered it all with a 1/2" layer of topsoil.
In a few months it was invisible to the eye and the lawnmower. As any
oldtimer to the band can attest I didnt wait very long in ANY pileup and
the most power I ever ran was 1200W. I still use that LK-500 amp today.
This QTH is using a pair of sloping verticals with elevated radials that
seem to work OK but a gut feeling says not as good as the old place.
Since I am moving in the spring who knows what I will try next. (Is
anyone interested in a fabulous ham QTH....before I take the 4 towers
down?).
73........Carl KM1H
After 5 years I moved and rolled up the mesh....it was still in perfect
condition.
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Sponsored by Akorn Access, Inc & N4VJ / K4AAA
|