[TowerTalk] Re:[Tower Talk] Silver Solder?

[K7LXC@aol.com]

In a message dated 00-01-27 11:40:31 EST, N4CW@aol.com writes:

> MAPP gas will handle silver solder outside/"in the elements". My concern is 
>  that the temperature would be too high and collapse the aluminum. Lead or 
>  Antimony-based solder melts at a much lower temperature, not threatening 
to 
>  relatively thin Aluminum tubing. Admittedly, lead solder isn't as strong 
as 
>  silver, but a joint that "sweats" well with tight-fitting tubing may be 
more 
>  than adequate. I don't recall anybody ever having done a study on that...

      My silver solder comments were primarily directed at quad joints (which 
was the discussion) and other wire terminations. I would never recommend 
someone solder aluminum elements joints. The constant working of the joint by 
wind action is surely a recipe for disaster (probably a stress riser point). 
I know there are aluminum soldering systems available but I don't have any 
antenna experience with them. 

     And don't forget the LXC Prime Directive: "DO what the manufacturer 
says". Does the manufacturer say to solder the aluminum elements? Didn't 
think so. Don't do it.

      If I want redundant mechanical security for an aluminum tubing antenna 
joint, I use a self-tapping TEK screw to further join them. It adds 
additional mechanical AND electrical coupling. This is a simpler, cheaper and 
more benign technique than sweating a solder joint on aluminum tubing. I 
wouldn't trust the average ham to get an aluminum solder connection right. A 
TEK screw, OTOH, is a slam-dunk for anyone. (Yes, this is a stress riser as 
well but a pretty small one. If you're going to use it on an element, use a 
small TEK screw <smaller hole - less stress> or put the screw on the bottom 
of the element where the stresses are less.)

Cheers,   Steve   K7LXC

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