Date: Thu, 27 Oct 2016 23:28:50 -0700
From: Jim Brown <jim@audiosystemsgroup.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Radial field question Single radial wires vs
mesh and more
On Thu,10/27/2016 10:10 AM, Kevin Kidd wrote:
> If it's not copper or some alloy thereof, don't waste your time for a
> permanent installation.
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.
73, Jim K9YC
## around town here, galvanized anything will disintegrate in the ground.
Ditto with my old qth 400 miles north of me. One fellow here in town, who was
renting a home, placed the bottom of his tower into the hole, then filled it
back up with dirt.
Guyed tower, so no worry about the base kicking out or anything. After 10 yrs,
the tower
was taken down. There was almost nothing left in the ground, it had eaten
itself.
## Having said that, the telco I worked for, used 6 ft galvanized grnd rods.
Any electrical
outfit will always use 8 ft copper clad rods, jack hammered into the ground.
I used 8 ft copper
rods, then cadwelded them to 2 gauge bare cu...aprx 2-4 inches below the
ground.
## I believe it depends whether the dirt /clay is alkaline..or acitic.
## What else that works is a 3-4 ft diameter /square piece of AL plate, like
.25 inch thick 6061-T6
etc. Vert goes in the middle. Then short and long radials from the
circumference of the plate. By adding the
shorter radials inbetween the longer ones, you can achieve the effect of a
screen at the base of the vert.
I did this on a 40m roof mounted vertical years ago, and drilled and tapped the
al plate. ( plate was only
12 inches square) The 60 x 15-30 foot long radials laid directly on the roof.
That was the best 40m vertical
I have used to date. The vert itself had to be lengthened quite a bit to
resonate the vert, since none of the radials
were resonant. Vert was guyed with dacron rope.
## Local al supplier has 4 x 8 foot sheets of al plate in any thickness....
like up to 2 inches thick..
( still dont know who buys al plate that thick).
Jim VE7RF
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