I installed my buried radial system in 1983, using #12 bare soft-drawn copper
and it is still in near-perfect condition. The radials were soldered to the
common point at the base of the tower, a copper ribbon laid around the
circumference of the base of the vertical, using a 15% silver alloy purchased
from a plumbing supplier. It comes in flat sticks, 18" long and about 1/8"
wide. I use a Mapp Gas brazing torch; a regular propane torch won't get the
copper hot enough. No flux is necessary. Copper soaks the stuff up like a
sponge soaks up water. Just brush off any scaly crud from the copper and the
heat from the torch will burn off the rest. The copper is heated to a barely
perceptible dull red. Be careful not to overheat the copper; I accidentally
melted the ends of a couple of radials into a blob but fortunately had enough
slack in the wire to pull it tight and retrieve enough length to make the
connections having to splice anything. After 33 years those brazed connec
tions are just as good as the day I installed them. The soil here is PH
neutral and pretty benign to copper; after all these years the radials show
very little deterioration.
Decades ago before I knew better, I had used regular lead/tin solder with my
first radial system, but the minerals in the soil turned the solder into a
white powder in just a few weeks and the connections would literally fall
apart. I ended up having to routinely re-solder the radials about once a month
throughout the radio season. It is against code to use lead solder in plumbing
for two reasons: the lead may react with minerals and leach into drinking
water, plus this eventually causes the soldered connection to deteriorate and
pipes to leak.
Commercial communications and broadcast systems DO NOT overlap radials in a
multi-tower array. A straight line is drawn between the bases of the towers,
and a second straight line is drawn perpendicular, at the mid-point of the line
between the bases of the towers. A copper conductor is laid out along that
perpendicular line. The radials to each tower are terminated and soldered to
that perpendicular conductor, with no overlap between the two radial systems.
Don k4kyv
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