Hi Gang,
Pete, N4ZR asks...."How do you achieve good all-weather connections
with the aluminum wire?
I asked the same question many years ago when I decided to use a ten
gauge stranded aluminum wire for my tri-band boomless cubical quad
elements. I simply made compression connections to the wires using
stainless bolts, nuts and star washers. The joints were waterproof
sealed with coax seal. I never had a bit of trouble with those joints.
The quad worked like "gang-busters" for years until the ice got it.
Then again, one has to ask... how do you normally make connections to a
beam element? No one I know of solders , welds or brazes the copper
coax center conductor or braid to an aluminum tube. Usually at some
point or other there is a self-tapping stainless steel sheet metal
screw or other standard stainless steel machine threaded bolt and star
washer / flat washer and nuts making the electrical connection by
mechanical compression and the joint somehow sealed from weather
penetration.
In some cases, I believe a berylium-copper star washer is used at the
point of electrical contact for good RF conductivity. The entire trick
is to avoid metals which are chemically very far apart in the
electromotive series which would cause electrolysis at the contact
points AND to avoid using metals which will readily oxidize. Now
aluminum WILL READILY OXIDIZE... but, at the point were contact is made
this is unlikely to happen where the metals are tightly compressed
against each other excluding the infiltration of air and water. Also,
to mitigate the oxidation problem, it is advisable to use a high metal
bearing paste such as Noalox or a good silicone grease at the mating
surfaces. This is also done where aluminum tubes are inserted inside
each other to make a beam element. The paste helps prevent the
oxidation of the mating tubing surfaces which, if not done, will
eventually make it totally impossible to ever remove the two mating
sections from each other.
Somewhere in all of this connection business is the fact that we are
dealing with RF which tends to flow on the surface of the conductors
making connections by contact and compression somewhat simple. Then
again, consider what is taking place in a SO-239 female coax connector
if one is being used somewhere in the antenna /coax chain. Silver(?)
plated metal spring leaves press against the silver-plated center
conductor pin of the male PL-259 completing the electrical contact. No
screws, no star washers, no direct high pressure applied via clamps
etc.. It works. All one really has to do is seal the whole assembly
from air and water infiltration and hopefully moisture in the air.
[sometimes wishfull thinking]
I hope my "take" on the subject is correct....as I've been doing things
like this successfully for years... and I rather suspect everyone else
is doing likewise. The only things left to contemplate are... finding
True North, avoiding unfriendly trees and being exceedingly carefull
not to run your radials through explosive septic fields.
Submitted for your consideration....
Roger, K2JAS.... back home in "2" land.
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