[AMRadio] 43' Vertical "How To" and Tutorial


D. Chester 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 
minerals.

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 
years.


Don k4kyv 



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