[SCCC] Copper Paste

Sun Jun 12 17:19:11 PDT 2011

Yeah, the behavior of silicone high-vacuum grease is a little 
counter-intuitive, but it works just as you describe, Glenn. It's 
designed not to evaporate at very low pressures (it's used in vacuum 
pumps), so at atmospheric pressure it is very inert. I almost always put 
a light coat of it on the center conductor and outer barrel threads of 
any PL-259s that I am installing in an outdoor environment. I've never 
seen it lead to a failure. If it somehow raised the contact resistance 
of a male-female UHF connector interface significantly the connections 
would go up in smoke at 1500 watts.

Great stuff.

73, Mike W4EF................

On 6/12/2011 9:36 AM, Glenn Rattmann wrote:
> 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
> _______________________________________________
> SCCC mailing list
> SCCC at contesting.com
> http://lists.contesting.com/mailman/listinfo/sccc
>
>