On BC MW AM installations, I use 15% Ag StaySilv bars for brazing
radials together, or to a common feed/EQ strap ring at the base of the
antenna, or strap running along a center line between two members of an
array where the radials will intersect.
I'll use alternately a Oxy/MAPP torch set, or small Oxy/Acetylene set,
conservatively valved, to get enough heat to braze. Torch choice is
based on which set is on the truck and which set has gas....
The same method/material is used for strap-strap joints, and along
angled strap folds, on both AM and FM BC site grounding jobs.
The keys/goals of this method are absence of Pb, and insurance of good
enough heat to totally flow the solder/Cu grounding system member.
This method was taught to me by broadcast "wintergreen".
My amateur radials, on the other hand, use far more dubious "cheap"
methods -- methods which I am embarrassed to publicly divulge -- on
account of a total lack of a working budget for things like welding gas
and silver brazing solder.. ;)
73,
- Josh / KF4YLM
On 1/1/2015 8:52 PM, Mike Waters wrote:
The silver solder I have here does have a high silver content, yes. :-)
It also contains cadmium, which shouldn't be used indoors because the fumes
are toxic.
It's 1/16" diameter round wire. When it's gone, I'll probably replace it
with a cad-free alloy.
I mostly heat the work (that is, the junction of ground radials, wire, and
ground rod), and let that melt the solder. Applying a flame to the solder
itself is an exercise in frustration. You're not doing that, are you?
73, Mike
www.w0btu.com
On Thu, Jan 1, 2015 at 4:37 PM, Paul Christensen <w9ac@arrl.net> wrote:
> “If you had trouble with an oxyacetylene torch, then I'll bet you
used "silver-bearing" (tin-copper-silver) solder, which melts at well under
700 degrees.
These are mid-level silver sticks with 15% silver + copper/phosphor and
have a working temperature of 1200-1400 degs. F – but not the 2-5% silver
bearing variety with a lower melting point. You are probably using a much
higher silver content if working with OxyAcet.
Using OxyAcet on the 15% bars can quickly result in boiling and
vaporizing of the solder with damage done to the copper, especially to a
copper strap. With 15% bars, Acetylene/air works fine even with a high
amount of heat-sinking. I have not yet tried MAPP gas.
Paul, W9AC
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