[TowerTalk] Al-to-Al

[Wayne Kline]

Some Say Tomatoes Some Say tomottoes  ...
As with most on the list antennas  are in our Blood.
my fist beam a Mosley TA33Jr. came with a  plastic tube of Gray Penetrox   My Stint as an industrial electrician  We use  Dow Noalox  buy the gallons on ALL connection  Bugs , Lugs and switch gear.
My first installation of the then Bencher Sky Hawks ( a three high stack ) during assembly then came with this GOOP called Monkey stuff ??? if my memory still intact.    Over the years of installing and assembling antennas it became painfully obvious  when any of the  products were not used in assembly. !!!
  I just last year  got my hands on an original design  Skyhawk and the elements  came apart  A -OK  but the GOOP !!!!  a red scrubby pad and lots of Lacquer thinner to clean the joint area.
 I assembled it with the  Jet Lube SS-30 Amazon .com

  Again my area is not In a Salt Spray environment   just ice,  snow, wind and rain  !!!

YMMV

Wayne W3EA
________________________________
From: TowerTalk <towertalk-bounces at contesting.com> on behalf of john at kk9a.com <john at kk9a.com>
Sent: Friday, February 16, 2018 1:23 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Al-to-Al

Penetrox has zinc particles and the SS-30 that K3LR uses has copper. Zinc
is much closer on the galvanic chart to aluminum than copper which
concerns me.

John KK9A

To:     towertalk at contesting.com
Subject:Re: [TowerTalk] Al-to-Al
From:   Patrick Greenlee <patrick_g at windstream.net>
Date:   Fri, 16 Feb 2018 09:42:52 -0600

Conductors (at least metals) are rated on an electromotive scale.  The
farther apart they are on the scale the greater the voltage generated when
an electrolyte is present. Stick a piece of aluminum into a lemon (citric
acid solution for electrolyte) and also stick in a piece of copper and
touch the two metals with your multimeter probes and note the voltage.
Switch over to current measurement and see the short circuit current the
little battery will produce.

When dissimilar metals (different ratings on the electromotive scale)
touch in the presence of an electrolyte (acid rain, salty ocean breeze,
etc current flows and the less noble metal is eaten away by  electrolysis
(AKA electrolytic corrosion.)

Zinc particles in an oil or grease base are protected from contact with an
electrolyte. When a joint has Penetrox or other equivalent zinc particle
bearing paste in it and is tightened the zinc particles are in contact
with the two substrate materials to be joined, promoting good conductance
and are protected from galvanic action by the oil/grease.  By itself zinc
is not magic and will corrode easily.  You wouldn't want to use zinc
washers in place of the zinc particle loaded paste.

Replaceable pieces of zinc are used on prop shafts and propellors to
protect the shaft and prop from damage by electrolysis. The zinc is
considered a "sacrificial element" as it is eaten away by electrolysis
while protecting the prop and shaft. Many of the 6 gal water heaters found
on RVs have replaceable sacrificial zinc rods in them. In that service
corrosion of the replaceable zinc is intentional to protect other
components.  In joining aluminum antenna components you don't want
corrosion and the zinc in the paste is not intended to be sacrificed to
protect the aluminum.

Anyone want to design sacrificial zincs to put on antennas?

Patrick        NJ5G

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