[TowerTalk] Silver Epoxy for Antenna Work?

[D. Scott MacKenzie]

I suspect that the reason that the brazes failed is because of galvanic
corrosion.  I suspect that the same will occur on the silver epoxy joints.
The primary reason is that the silver is substantially anodic to the
aluminum, resulting in preferential corrosion on the aluminum.

The epoxy may also be limited in its ability to carry current - but if that
were the only thing - I would try it.  Because of the corrosion voltage
potential difference between the aluminum and the silver epoxy, I think that
premature failure will occur.  I think riveting the rods would last much
longer than the brazed or silver epoxied joints.

Scott, KBOFHP

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of Dan Levin
Sent: Wednesday, September 14, 2005 11:15 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Silver Epoxy for Antenna Work?


In the past, I have used aluminum "welds" (actually brazes, using a propane
torch system) to attach capacity hat rods to aluminum tubing for my 40 meter
yagi.  The brazes are cracking, resulting in loose joints that arc.  I need
to come up with another plan.

One option is to use silver bearing epoxy to attach the rods to pieces of
aluminum angle, then use rivets to attach the angle to the elements.  This
epoxy is conductive, and appears to have been developed to allow repairs to
be made on PC boards.

Has anyone used silver bearing epoxy at RF before?  My concern is that
either the current carrying capacity isn't sufficient, or that it is lossy
at RF.

Thanks for any input in advance.  Comments of the form "why don't you use
attachment method X" are welcome, but I really need an answer to the
question "will silver epoxy work?"

			***dan, K6IF

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