-----Original Message-----
From: Dubovsky, George
Sent: Tuesday, July 27, 2004 2:50 PM
To: 'Tom Rauch'; Michael Tope; K7LXC@aol.com; "\"
<chief@thechief.com>,"TowerTalk" <towertalk@contesting.com>
Subject: RE: [TowerTalk] Lightning protection questions.
When Tom says "silver solder" in this context, he means brazing. This is
NOT soft solder by any stretch of the imagination. For a quick look at
the temperatures involved, go to:
http://www.jwharris.com/
Click on Phos/Copper Brazing Alloys and on High silver Brazing Alloys,
and then scroll down the page to see the tabulated solid and liquid
temps involved. Phos/Copper (aka "silfos") with small amounts of silver
(5% or so) is what is commonly used in refrigeration tubing work - it's
as strong as the base copper tubing and not all that expensive, because
of the low silver content. Usually the heat source is an acetylene/air
torch.
The more silver added to the mix, the more fluid the molten braze is.
45% silver braze will flow into tiny cracks. In fact, you can't bridge
gaps very well with the high silver alloys; the 5% stuff is more
forgiving of bad fitup of the joint. Note also that the melting point
comes down with increasing silver content, but boy howdy does the price
go up!
All of these brazing materials are fluxed with the same white stuff. I
don't recall what it is exactly, but if it powdered, you add water to
make a paste. If it's a paste already, you're good to go.
I believe that any of the common brazing materials are as good as the
base copper as far as current handling (lightning) is concerned, but I
suspect that they are not "approved" joining methods for grounding stuff
because a certain amount of skill is required to do it properly.
73,
geo - n4ua
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Tom Rauch
Sent: Tuesday, July 27, 2004 2:17 PM
To: Michael Tope; K7LXC@aol.com; "\" <chief@thechief.com>,"TowerTalk"
<towertalk@contesting.com>
Subject: Re: [TowerTalk] Lightning protection questions.
> What alloy are you using, Tom. Most of the stuff you can
buy at
> home box stores is for plumbing applications (96%Tin, 4%
Silver).
I've been intending to pull and invoice and look, but
welding supply houses sell the correct materials. For small
quantities (such as attaching taps on tubing coils for tank
circuts) we used to buy solder from sources like Granger and
McMaster Carr.
When I eventually reorder some, I'll make a note of the
exact material. The material I use is barely melted with
Mapp gas, and uses a white paste flux. I'm sure it is also
used in refrigeration applications.
73 Tom
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_______________________________________________
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and ask for Sherman, W2FLA.
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