I'm not sure I'd rely on any "solder" for strength of the connection for
radials. The solder would be there only to preserve the electrical
connection and I'd rely on some sort of mechanical connection for the
strength. For that purpose, the primary consideration would be that the
solder be lead free (it leaches out in moist environments) and almost
any silver solder (like that used to meet plumbing codes and commonly
available at Lowes, HD, etc) ) should work. The key is that it not have
lead ... not how much silver it has.
For lightning protection (or any high current application), solder seems
to me to be a very poor choice. Solder, including silver solder, almost
invariably will be the highest resistance element (and the weakest
thermally) in the system and will act like an explosive fuse if it takes
a hit. As Jim says, clamps or welds are the way to go for this.
73,
Dave AB7E
On 8/7/2015 9:51 AM, Jim Lux wrote:
On 8/7/15 9:24 AM, mike stokes wrote:
Hello
I need to improve my radials and lightning protection. What Silver
Solder
is best for the job and where is a good place to purchase it ?
I'm not sure silver solder (called silver brazing these days) would be
appropriate for lightning protection. It's certainly not what the
code requires for grounding (approved clamps or exothermic welds),
although I think it's a reasonably workable solution.
For RF purposes (e.g. your ground radials), though, silver brazing
isn't a bad idea. It's rugged, it's easy (assuming you have the right
equipment).
I doubt that the specific alloy makes a lot of difference. What you're
really looking for is that the melting point is higher than that of
tin/lead, and that it's mechanically more rugged. I've used a variety
of "hard solders" from the local hardware store. Typically, they are
around half silver (price varies with silver content). Pretty much
anything will work with copper/brass (if you're brazing steel, you
need to be a bit more careful in material selection). A typical alloy
is something like Silvaloy 355 which is about half silver, 1/5th
copper, and the rest zinc and tin. No cadmium. At least that's what I
found out in the garage that still has a label on it.. I'm not a pro
welder, with ovens to keep my rods dry, records of material certs,
etc.. Others on this list ARE much more knowledgeable and may have
some recommendations on the best alloys.
As with all "melt metal to stick metal together" things, the right
flux and the right heat source is probably more important than the
actual metal you're melting.
I use the solid white paste flux, and I've used both a oxy-mapp rig
(one of the ones with the two "propane torch" sized bottles) and a
oxy-acetylene rig (with a fine tip on the torch). Either works. The
bigger rig (with big bottles, either oxy mapp or oxy acetylene) is
nicer because you don't worry about running out of gas. If you could
borrow or rent the rig, life is easy.
Silver solder alloys melt around 1000F (compare tin-lead at <400F),
but lower than bronze brazing rod (typically >1500F). Note that 1000F
is "red heat"
I'd say that in a few hours, if you've got experience soldering
(especially if you've done plumbing) you can crank out perfectly
serviceable electrically and mechanically brazed joints. They may not
be pretty, they may not be something you'd trust your life to for
mechanical reasons, but they'll work fine.
I find brazing, in general, MUCH easier than doing good plumbing
fittings with soft solder and a propane torch, and MUCH easier than
real fusion welding.
With real welding, you have to worry a lot about the metal you're
welding, and getting the temperature right, and getting just the right
penetration (whether gas or arc), and it's a lot hotter. With soft
solder and plumbing, there's a real art to getting the right flux, and
the right temperature on the whole joint (not too cold, not too hot)
so that you get a nice even solder layer with no pinholes and no
globs. And with plumbing there's always the whole "wet pipe" and
"don't light the wall on fire" thing.
A small oxy-gas torch has a nice small hot flame that's easily
adjustable and not too bright, and there's a big temperature range
over which a good joint can be made (iron and steel melt at >2500F,
copper melts at 2000F, the brazing filler melts 1000F less, so lots of
room between), and the overall lower temperature means you don't need
as much eye protection, so you can *see* what's going on.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|