[SCCC] Copper Paste

[Paul / N6LL]

Very interesting, Glenn.
I wonder how much capacitance there between clamped telescoping tubes with a 
very thin aluminum oxide dielectric. We only need DC continuity in an HF 
antenna for static discharge.
73
Paul
----- Original Message ----- 
From: "Glenn Rattmann" <k6na at cts.com>
To: "Dennis Younker NE6I" <ne6i at cox.net>
Cc: <sccc at contesting.com>
Sent: Sunday, June 12, 2011 9:36 AM
Subject: Re: [SCCC] Copper Paste


> Apply it the same way as you did the Penetrox (inside the joint).
>
> Yes, silicone grease is a dielectric.  So is the petroleum-based
> carrier in the Penetrox.  The silicone material is more inert and
> doesn't disappear like the petroleum-based stuff will do, leaving the
> unprotected particles of other material in there.
>
> If you looked at the aluminum surface with a microscope, after prep,
> you would of course see a rough landscape of bumps and grooves-- not
> smooth.  When the two surfaces are mashed together tightly with a
> hose clamp, and a screw added, don't worry-- plenty of the high spots
> are going to mate up with other high spots, regardless of the
> presence of the dielectric, and make contact.  That is the series of
> multiple contact points from which we are trying to eliminate the oxygen.
>
> The various 'conductive pastes' are ok in the short term, but
> eventually the carrier deteriorates and we are left with oxidized
> particles of other material in there, and it's probably no longer
> conductive.  In the long term, this is bad news.
>
> IMHO....
>
> --Glenn K6NA
>
> At 08:33 AM 6/12/2011, you wrote:
>>Glenn,
>>
>>Isn't silicone grease an insulator? Or are you saying keep it out of
>>the joint itself but coat the exterior of the joint once the two
>>pieces of aluminum are slid together? What we used to do with our
>>KLM antennas is clean the aluminum where the two pieces slide
>>together, coat the outside of the smaller piece with Penetrox, coat
>>the inside of the larger piece with Penetrox, slide the two together
>>and clamp securely.
>>
>>--Dennis
>>
>>
>>----- Original Message ----- From: "Glenn Rattmann" <k6na at cts.com>
>>To: "Bob Wilson" <N6HB at n6hb.org>
>>Cc: <sccc at contesting.com>
>>Sent: Sunday, June 12, 2011 8:06 AM
>>Subject: Re: [SCCC] Copper Paste
>>
>>
>>>If folks don't like what they are reading here, just go to the
>>>endless archives on Tower Talk and find another opinion you like better! 
>>>;-)
>>>
>>>Any of these items mentioned will work adequately for a while (except
>>>for Cu - Al-- a bad recipe for antennas, I have seen really bad
>>>results with that).  Zinc or aluminum particles in the mix are the
>>>'least dis-similar' metals for the aluminum joint.  However, the
>>>primary way these products work is by keeping oxygen and moisture out
>>>of the connection.  That's what will prevent aluminum
>>>oxidation.  Over time, the carrier tends to vaporize or dry out, and
>>>the moisture/oxygen start doing their business.
>>>
>>>Dennis mentioned "We know aluminum to aluminum causes a black
>>>corrosion in short order."  I don't think that's true.  The initial
>>>aluminum oxidation layer is basically colorless-- you can't see
>>>it.  After a very long time, it may be white.  It's an
>>>insulator.  What Dennis mentioned I think is the remnants of old
>>>No-Al-Ox or Penetrox, which leave behind a dry, black insulating
>>>layer after the carrier washes out or vaporizes.  Eventually coupled
>>>with the aluminum-oxidation layer, the hard black layer of gunk makes
>>>it even worse.
>>>
>>>High-vacuum silicone grease (o-ring grease), with NO particles mixed
>>>in, is the simplest anti-oxidation material to put in there.  Use a
>>>tight, stainless hose clamp around the slotted end, and add one s.s.
>>>tapping screw (coat the threads, too) behind the clamp, into both
>>>layers of aluminum.  I've taken apart joints like this after 20 years
>>>and they are still fine.
>>>
>>>Remember though, even your brand-new aluminum tubing comes to you
>>>already oxidized (insulated!).  Remove this invisible layer before
>>>you mate the joint.  Use non-metallic grit sandpaper, wipe clean with
>>>lacquer thinner, and then QUICKLY coat both halves of the joint with
>>>the grease.  A fresh aluminum surface oxidizes in just minutes, so
>>>the key is to cover the fresh surface immediately with the goo to
>>>eliminate the oxygen.  Then mate the pieces.
>>>
>>>Oh-- don't have any silicone grease handy?  Just use common
>>>wheel-bearing grease.  The next time N6ND beats you out in a pileup,
>>>you can think about the common grease in Rick's antenna joints.
>>>
>>>73,
>>>
>>>Glenn K6NA
>>>
>>>At 09:59 PM 6/11/2011, you wrote:
>>>>Noalox is the "gold standard" - I've seen it at Home Depot in the 
>>>>squeeze
>>>>bottles you refer to AWA small tubes. I've also bought large containers 
>>>>at
>>>>electrical supply houses and used it for a Caribbean contest expedition. 
>>>>We
>>>>donated the antennas, and I heard back 5 or 6 years later that they came
>>>>apart like the day they were put up.
>>>>
>>>>-Bob
>>>>
>>>> > -----Original Message-----
>>>> > From: sccc-bounces at contesting.com 
>>>> > [mailto:sccc-bounces at contesting.com]
>>>> > On Behalf Of Daniel Severance
>>>> > Sent: Saturday, June 11, 2011 8:39 PM
>>>> > To: Timothy Coker; Dennis Younker NE6I; SCCC
>>>> > Subject: Re: [SCCC] Copper Paste
>>>> >
>>>> > Noalox (or any of the other variants) is what I've been told to use 
>>>> > as
>>>>well -
>>>> > without it over time the pieces will weld together so you can't even
>>>> > disassemble to clean up joints.  I have had experience trying to
>>>>disassemble
>>>> > and antenna which has fused in places.  Definitely use one of
>>>> the > products
>>>>-
>>>> > the Noalox comes in a bottle which looks like an old elmer's
>>>> glue > bottle,
>>>>at
>>>> > least for one of the sizes (if that helps you find it)
>>>> >
>>>> > Cheers,
>>>> > Dan
>>>> >
>>>> >
>>>> >
>>>> > ________________________________
>>>> > From: Timothy Coker <n6win73 at gmail.com>
>>>> > To: Dennis Younker NE6I <ne6i at cox.net>; SCCC <sccc at contesting.com>
>>>> > Sent: Saturday, June 11, 2011 10:42 PM
>>>> > Subject: Re: [SCCC] Copper Paste
>>>> >
>>>> > Noalox from Lowes is what I have been using. It's meant for aluminum
>>>>joints.
>>>> > $9 for 4oz or so.
>>>> >
>>>> > 73,
>>>> >
>>>> > Tim / N6WIN.
>>>> >
>>>> > On Sat, Jun 11, 2011 at 7:38 PM, Dennis Younker NE6I
>>>> <ne6i at cox.net> > wrote:
>>>> >
>>>> > > Hmmm. We know aluminum to aluminum causes a black corrosion in 
>>>> > > short
>>>> > order.
>>>> > > That corrosion is an insulator.  We also know that dissimilar 
>>>> > > metals
>>>> > > cause corrosion. I hadn't thought about copper to
>>>> aluminum > > previously.
>>>> > > In my past experience though, Penetrox applied to aluminum
>>>> yagis was > > a
>>>> > > positive experience. Penetrox was shipped with KLM antennas 20+ 
>>>> > > years
>>>> > > ago. I've been out of touch since then.
>>>> > >
>>>> > > Your suggestions of products at Home Depot is intriguing.
>>>> > >
>>>> > >
>>>> > > --Dennis, NE6I
>>>_______________________________________________
>>>SCCC mailing list
>>>SCCC at contesting.com
>>>http://lists.contesting.com/mailman/listinfo/sccc
>>
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