To all;
If it is going outside in the weather atop a tower or you plan to leave it
where you can get to it, may I suggest that you put at least two (2) layers
of Scotch 88 as a courtesy wrap under the RTV or what ever you use so if you
do need to re open for any reason you can do so. Especially over expensive
connectors (will keep the RTV out of threads and off of the actual
connection) . This is something we have used in the tower industry for years
and it works.. We also use "Vapor Wrap" from DB / Andrews and Scotch Coat
which is a rain on type of sealant. These products are not cheap but are
what have been used by tower crews for years.
Hope this helps and did not mean to barge in.
Doug
----- Original Message -----
From: Jim Lux
To: Michael Keane K1MK
Cc: towertalk ; DENNIS BRICKEY
Sent: Tuesday, February 05, 2008 11:03 AM
Subject: Re: [TowerTalk] RTV? What Kind?
Michael Keane K1MK wrote:
> The other thing about using RTV is that RTV needs
> to be exposed to moisture to cure. So you don't
> want to cover up RTV with anything like tape or
> other sealants at least until the full cure time
> of the RTV, otherwise the RTV will never fully harden but rather remain
> tacky.
I believe this is only true for the one-part RTVs.. the two part RTVs
do not require exposure to moisture, and tend to outgas less.
I suppose it comes down to whether one wants caulk or a potting compound.
Either type is available from the usual mail-order sources (Newark,
Mouser, Allied)
MG Chemicals is the new company that handles what used to be GE
silicones. http://www.mgchemicals.com/products/silicones/guide.html
Walks you through which one you need (then you can hope that the minimum
quantity isn't a 55 gal drum). They cover things like thermal
conductivity (important for some applications, e.g. potting a balun or
HV power supply), cure types, etc.
For instance, a 2 part RTV12 is intended for electrical potting, is
primerless, and translucent and fairly runny (1500 cps). RTV11 is much
stiffer, white, and much harder after cure.
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