[TowerTalk] Radial connecting plates

[Donald Chester]

I use a piece of 2" wide heavy gauge copper strap which surrounds the base 
of the tower in a  rectangular ring.  The radials are silver-soldered to the 
strap, and there are 4 pieces of strap soldered to the ring and leading to 
the ground connection at the base of the tower.  The ring and radial 
terminations are buried about 2" below the surface of the soil. If you 
cannot find copper strap in your local area, ordinary 3/8" copper tubing 
should work just as well. I salvaged my copper strap from some kind of large 
air-core rf transformers I stumbled across at a surplus outlet.  Copper 
strap is generally used to ground broadcast towers, so anyone who performs 
tower maintenance should be able to get you a few feet.

I think this is a MUCH better method than one of those plates with screws to 
attach each radial, and a lot cheaper, even considering the recently 
inflated price of copper.  I would consider the plates a waste of money.

But never, ever use regular lead/tin solder for any connection that may come 
in contact with the earth.  I found long ago that my soil attacks the 
soldered connections, and very quickly turns the solder into a white powder. 
  I once had a radial system soldered together with lead/tin, and had to 
routinely re-solder all the radials about once a month.  Otherwise, the 
solder deteriorated and the radials would literally fall off the ring.

So the last time around I used a silver-alloy brazing rod, purchased from a 
plumbing supply outlet.  The rods come in about 18" lengths, in the form of 
a flat rod, about 1/8" in diameter.  No flux is needed; copper wicks up the 
molten alloy almost like a sponge wicks up water.  All I ever had to do was 
clean the copper well enough to remove any loose scales of oxide or any 
paint, grease or other contaminant.  An ordinary butane torch won't heat the 
copper hot enough, but MAPP gas, that is sold in a cylinder much like 
butane, will do the job; it should be available at the  same plumbing 
supplier as the rods.  The copper must be heated to a dull red glow - but be 
careful; the MAPP gas is capable of overheating and melting the radial wire! 
  Once the copper is heated just enough to melt the alloy, you simply apply 
the brazing rod to the copper and it should take the molten solder 
immediately.

I built my 160m vertical in 1983, and whenever I periodically check the 
brazed connections (every 2-3 years), they look as good as they did the day 
I soldered them.  They solder turned a dark charcoal grey the day I 
assembled the radials and that's exactly how I find them to-day whenever I 
inspect the connections.

Don k4kyv

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