Topband: Soldering radials?

[Donald Chester]

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 connections 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