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Re: PCSAT2 ready for flight

> We didnt do the coating ourselves (its easy enough) but
> that wasnt our job in this project.  So I know nothing about it
> other than it is kinda rubbery and you can easily pull it off
> if you can get a-hold of it.  Its like a thin very flexible rubber
> coating.  Its not like the HARD plastic stuff they use on
> Earth that also helps with mositure blockage etc...
> Maybe someone else on AMSAT-BB knows the name of
> the stuff.  ALso, it only detuned our open-air RF coils
> slightly so that we noticed about a 10% loss in power.
> We decided that was OK and did not try to re-tweak...
>> I purchased some (new) water based material when I was
>> in UK last year  (Humiseal 1H2O) but they still haven't any
>> outgassing figures for it.
> One thing we did was take a spare (junk transmitter) that
> had other problems and had it coated first so we could
> see how it changed.  Nothing other than the 10% above.
> AND we found that we could ask for anything to be
> masked and not coated.  They had little stickers that
> they would stick onto anything we didnt want coated.
> We put those over the top of the coil cans.
> We let them coat the variable caps because this stuff
> is so easy to remove, just an exacto knife to cause a
> little incision and you could pull the stuff off the top of
> the cap in once piece...  It coats, but does not "stick"
> to stuff much more than "post-it"notes do...
> Ill see if I can find out what it is...
> Bob

I'd say it sounds like a "hot dip strippable coating", from the 
description.  There are some that are low residue enough to use to coat 
stuff like this and dip at a low enough temperature that they'd be 
within the soldering temperature envelope, at least for SMT.  It's also 
extremely viscous when melted so it doesn't flow into small openings 
much at all.

They used to use this stuff to package machine parts and electronic 
components for shipping during WWII, i think, although what they used 
was a much heavier version.  I also got a new crankshaft for one of my 
engines one time that was completely covered in a HDSC compound to 
prevent rust.

Check out http://www.dipseal.com -- they have a pretty wide range of 
HDSC products.  Might be enlightening .. and might be worth looking at 
for non-space related ham needs as well .. ;-)

Version: PGP 8.0


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