[Elecraft] New KPA100 Rev.

[Don Brown]

Hi

My company manufactures a small controller used on aerobic sewage treatment 
plants. I have over 50,000 of them installed. One of the requirements is to 
seal all of the electrical wiring where it enters the controller box using 
silicone rubber. This is to keep chlorine, HS2 and water vapor out of the 
box. We provide a 4 Oz tube of GE Silicone II so our installers will not use 
the wrong type of silicone. The Silicone II is alcohol based rather than 
Acetic acid based (vinegar). I have received several circuit boards returned 
with green corrosion on the resistor leads and circuit traces due to the 
wrong type of silicone used. We found this because the silicone we provide 
is clear and the installer had used white bathroom calk bought at the local 
hardware store. I guess he lost the tube we provided in the parts kit.

I would not recommend any adhesive be used on any Elecraft kit just as it 
states in the manual. The wire leads are strong enough to hold the toroids. 
If you must use something I would suggest a small strip of double stick foam 
tape.

Don Brown
KD5NDB


----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at earthlink.net>
To: <elecraft at mailman.qth.net>
Sent: Wednesday, October 18, 2006 9:35 AM
Subject: RE: Re: [Elecraft] New KPA100 Rev.


> David,
>
> I beg to disagree, some time ago I used some of the 'vinegar' stuff on a
> splice with insulated copper wire (#14 THHN) - and I can say that the bad
> stuff keeps creeping for a long way.  After a couple years, I had occasion
> to examine it and found the stuff had crept up under the insulation and
> caused corrosion as much as 6 inches from the point where it was applied -
> It did make a good weather seal, but at the cost of electrical properties
> loss.  Fortunately, this was not in any critical application.
>
> No longer will I use commonly available RTV direcly in electronics
> applications - even the consumer grade 'non-corrosive' RTV commonly
> available that I bought recently had a vinegar smell to it.
>
> 73,
> Don W3FPR
>
>
> > -----Original Message-----
> >
> > I think too much is made of so-called corrosive RTV (it's the
> > vinegar).   The level of corrosion to bare metal is very small
> > and in free air stops fairly quickly.  For other components
> > bathroom sealant is perfectly adequate.  Enamelled copper wire
> > and toroids should be immune anyway.
> >
> > David
> > G3UNA
> >
> >
>
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