[Top] [All Lists]

Re: [TowerTalk] soldering radials (or any outdoor connection)

To: <>
Subject: Re: [TowerTalk] soldering radials (or any outdoor connection)
From: Donald Chester <>
Date: Sun, 27 Mar 2011 05:23:18 +0000
List-post: <">>
Back in the 70's I bonded a radial system to the common point at the base of my 
inverted-L using ordinary lead/tin solder.  I quickly discovered that the 
solder reacted with moist earth and almost immediately turned into a white 
powder, and the soldered connection literally fell apart, just in a matter of 
weeks.  I ended up re-soldering the radials about once a month for the entire 
winter season.  I would  never recommend using lead/tin solder for any outdoor 
connection exposed to the elements, particularly  where it is in contact with 
the soil. Slopping roofing tar over the soldered connection might extend the 
life of the connection through one season without having to re-solder, but I 
would not trust this to be a satisfactory permanent solution. Nor would I use 
any of those Hammy Hambone "radial plates" on the market that use screws to 
hold the
 radial wires to the base of the antenna.  The freeze-thaw cycle will 
eventually cause the screw connections to work loose and result in 
poor connections. The radials must be solidly BRAZED to the common point.

To bond your radials to the common point and join together other outdoor 
connections, I recommend the following: Buy a small tank of Mapp gas and 
brazing nozzle (don't try to use a propane torch nozzle).  I bought mine back 
in 1980 for just a few bucks, but now I think the outfit runs $30-$50, 
but it is well worth it.  Buy some silver alloy brazing rods (not cheap,
 but not outrageously expensive either). They come in flat sticks about 
18"  long and  1/8" thick.  You don't need any flux, and the copper 
doesn't have to be polished; just scrape off any flaky scale and clean 
off any paint or grease.  The heat from the torch will burn away the 
dull oxide patina on the copper and you will see a dull metallic pink hue 
beneath the flame.  Heat the copper until the brazing rod begins to melt
 - pretty much the same as you would with regular lead/tin solder; let 
the hot copper do the melting, not the flame itself.  If it is away from 
direct sunlight, the copper should display a dull red glow. Once the 
melting point of the silver alloy is reached, copper will soak up the stuff 
like a sponge 
soaks up water. I have never seen it blob up and run off the copper the 
way lead solder sometimes does when the metal doesn't want to take 
solder. Just be careful, because it is very easy with Mapp gas to 
overheat the joint and melt the copper wire.  Never let the 
copper reach a bright orange. With a little practice, maybe after 2 or 3
 radials, you should have the hang of it.

The Mapp gas outfit and
 brazing rods are sold at welding and plumbing supply stores.  
Sweating  copper pipes with ordinary lead/tin solder is 
against code, because of concern about lead leaching into the water, and
 I would suspect that the lead joint would deteriorate with moisture and
 minerals in the water, just as it does in contact with wet soil. The use of 
silver brazing for plumbing work has created enough of a demand for the 
material to keep the price reasonable.  I have also 
seen Mapp gas sold at Lowe's, but didn't check on the silver rods.  They
 make several grades of silver rods (based on silver content I suspect);
 I would explain to the salesmen at a plumbing or welding supplier what 
you intend to do, and they might be able to recommend which grade would 
be best.  I don't recall which I purchased, but I would look for what 
holds up best in contact with the soil and best adheres to the 
copper during the brazing process using the Mapp gas torch. The cheapest may 
not be the best.

During the soldering process, 
the alloy will melt and turn to a bright shiny silvery texture, almost 
like liquid mercury. When finished, the joint will cool down and turn to
 sort of a charcoal grey when it hardens. I put up my present vertical and 
radial system in the early 1980s, and after almost 30 years, the bonded 
show no signs of deterioration, and the brazing looks almost exactly the same 
as the 
day I put it together. OTOH, some screw-on ground clamps I attached to the guy 
anchors have worked completely loose and I can wiggle them by hand.

Don k4kyv


This message was typed using the DVORAK keyboard layout.


TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>