On Fri, 8 Jun 2012 12:17:28 -0700 (PDT), JIMMIE
wrote:

I was thinking about using fiberglass reinforced body
filler as an insulator and was hoping someone here
may have some experience doing the same. It would be
used to support the low impedance end of a gamma match.
Power level not to excede 200 watts HF.

There shouldn't be much voltage at the gamma match feed point.

Which fiberglass filled body putty where you considering?
http://3mcollision.com/products/fillers-and-glaze/reinforced-fillers

Looking at the various MSDS sheets, it looks like a reasonable
insulator that's not going to absorb moisture.
My comments and guesswork in [xxxx]:

1,3-ISOBENZOFURANDIONE, POLYMER WITH 2,5-FURANDIONE AND
2,2'-OXYBIS[ETHANOL] 30 - 60%

[The volatile solvents.]

TALC 10 - 30%

[Good insulator. Steatite insulators are baked talc.]

STYRENE MONOMER 10 - 30%

[Styrene monomer is probably propylene oxide. I couldn't find
anything in its electrial properties. My guess(tm) is that it's quite
good as styrene plastics are sometimes used as insulators.]

MAGNESIUM CARBONATE 10 - 30%

[That's chalk. It's hygroscopic and absorbs moisture. It's probably
there to remove any water from the talc, which will make talc
conductive.]

CHLORITE (MINERAL) 1 - 5%

[That's a harder form of talc. My guess(tm) is that it serves the
same purpose as the soft talc, but is there to help prevent shrinkage
during hardening. I'm not sure this is correct.]

FIBERGLASS Mixture 1 - 5%

[There's the fiberglass filler. Of course, glass is a good insulator.
However, I don't think 1-5% fiberglass by weight is going to add much
insulating ability to the mix. You might as well use Bondo, without
the filler.]

FIBER 0.5 - 1.5%

[Same as fiberglass]

OXIDE GLASS 0.1 - 1.0%

[Any of a dozen glass oxides. All are good insulators]


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Jeff Liebermann
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Santa Cruz CA 95060 http://802.11junk.com
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