|[AMRadio] 43' Vertical "How To" and Tutorial|
k4kyv at charter.net
Mon Dec 1 21:00:35 EST 2008
There are a couple of things I would do differently in building the radial
ground system. It is a good idea to use insulated wire if available, since
the insulation protects the wire from soil corrosion and will extend its
life. But why do you recommend stranded wire (unless that's what happens to
be available at a good price)? Solid copper will last much longer than
stranded in the corrosive environment of the soil, and even with the
insulation, some of the wire will inevitably be exposed to corrosive
Using the staples, the wire will bury itself within a year or two. First,
with regular mowing, the wire will become buried under the thatch, and
within a season will be embedded in the sod. I have left copper wire lying
on the ground for some period of time, and when I retrieved it, it was
buried a quarter inch or so under the surface of the soil, and it took a
real effort to pull it up. I did mine the hard way, burying the radials
about 2" in the ground using a special plough attachment to a garden tractor
that I built for the occasion, but if I had it to do over again, I would
probably just lay the radials on the ground and let them bury themselves
with the help of Mother Nature.
Rather than using a stainless steel plate with screw terminals, it would be
much better to use copper strapping or a heavy solid copper conductor, or
even copper tubing, to make a bus bar in the form of a circle or rectangle
around the base of the vertical. Braze the radials to the copper bus bar,
using a silver alloy solder that is available at any plumbing shop. It
comes in sticks about 18" long, flat about 1/8" width. No flux needed.
When the stuff becomes molten, copper sucks it up like a sponge sucks up
water. The only thing you have to clean off the copper is any badly
oxidised areas or surface scale. The brazed connection will last for ever
even buried in the soil.
Never use lead/tin solder to solder ground wires or radials. When exposed
to the corrosive soil, within about a month all the solder will turn to a
white powder and the soldered connection will literally fall apart. The
silver alloy stuff, while not dirt cheap, is reasonably priced because it
abundant, mandated by building codes for plumbing, because with lead/tin,
there is concern that the lead might leach into the water line.
You will need a brazing torch and a tank of Mapp gas. A regular butane
torch will not get hot enough to melt the silver alloy. Be careful not to
get the copper hotter than a dull red glow. It is very easy to melt copper
wire into a blob with the mapp gas torch.
I have inspected some of the brazed connections in my ground system that
used the silver alloy solder, and they are still intact after more than 25
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