[TowerTalk] (no subject)
K7GCO@aol.com
K7GCO@aol.com
Fri, 17 Mar 2000 07:17:56 EST
In a message dated 16.03.00 16:31:35 Pacific Standard Time, K7LXC@aol.com
writes:<<
In a message dated 03/16/2000 1:53:00 PM Pacific Standard Time,
K7GCO@aol.com writes:
> Penatrox has one serious problem--it has ZINC in it I'm told. That's a
"dissimilar metal" and exactly what you don't want at that thin ring of
electrical contact at the diameter change.
Well, the PARTICLES are zinc but they're held in suspension in a
"natural base compound". The natural base vehicle prevents the tiny zinc
particles from exposure to air and thus oxidation. The purpose of the
particles is to pierce the thin oxidized layer to the metal underneath and
make an electrical connection. They're too small to be much of a problem; I
wouldn't worry about it - Penatrox is a recognized useful antioxidant.
Cheers, Steve K7LXC Tower Tech
When I assemble a beam I always clean the joints and immediately apply the
grease I'm using. I do not need to use Zinc to penetrate the layer of thin
Aluminum Oxide even when I use just Silicone grease. That's what my HP low
resistance ohmmeter tells me. I suggest you clean the joint first and you
won't need a dissimilar metal to make contact through the Aluminum Oxide you
have. Moisture is the 3rd factor in corrosion and the grease doesn't
completely isolate the Zinc particles. Electrical contact beyond the thin
ring of RF contact at the diameter change is not needed--skin affect you
know. Only at the diameter change.
I have explained several times now that after using Penatrox for 20 years and
observing many failures, I do not under any circumstances buy your views the
Zinc particles are too small to very cause a problem. I don't recognize it
as an effective antioxidant for even more reasons than I have previously
stated.
A W6 told when he checked his beam after several years, he had to file the
Penatrox off. He ran big power and I think he cooked the joints with 14 MHz
RF.
Mike Ercolino of Telrex some 40 years ago at his factory told me "he ran
accelerated aging tests on Penatrox of spraying salt water and heat tests and
was unhappy with it." I didn't listen and had to find out for myself at a
slower rate.
I can quote a lot more but will end with the following that just was posted
and sums it up completely I would think for anyone other than those who are
still in the dark.
In a message dated 16.03.00 17:39:51 Pacific Standard Time, dx@northcoast.com
writes:<<
Disunirregardless, I have put together probably 100 aerials w/Penatrox ..
so... whatever. I have noticed that after 6 or so years, the compound gets
a little "gummy", but before re-assembling the antenna, some solvent on a
rag takes care of that, then re-apply the Penatrox. One query I have, is
that I have used fine steel wool at times for burnishing the elements, and
found out that was not a very good idea ... so, switched to the coarse steel
wool, then use a clean rag to wipe down before assembly ... any thoughts on
this steel wool thing? Mark . AA6DX
Don't use Dissimilar Metals no matter how small they are. The Penatrox case
is closed. Several posts have given great advice on how to use Steel Wool or
Scotch Brite.
As I have said several times, "Properly designed Quads using cooper wire have
only one soldered permanent joint per element that never needs maintenance or
other yagi Band-Aids." There are no Web Site Reflectors for properly
designed Quads. I'd like to start one to advance the Quad State of the Art
even more and make them even more effective. Would you believe that Aluminum
Oxide is getting resistant to all these inhibitors and the "Dreaded Aluminum
Joint Cancer" is running out of control. Yagi's are failing all over. Quads
are totally immune to this insidious disease. k7gco
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