On Sat, 09 Jun 2012 09:45:30 +0100, Jeff wrote:

Put a sample in the microwave and see if it get hot, it may be an
insulator but it also may be lossy at rf.
Jeff

That's a good way to determine if it will work at 2.4GHz. However,
this is for HF, which is about 1/500th of 2.4GHz. Some insulators
that fail at 2.4Ghz (PVC, nylon, phenolic, wood, bakelite), work just
fine at HF frequencies. In general, if it passes at 2.4GHz, it will
probably work at HF. However, if it fails, it may still work at HF.

There's also the potential problem of volatiles and solvents. Some of
the components in the body putty are hygroscopic (absorbs moisture).
When baked in a microwave oven, the water and solvents may boil,
resulting in cracking or crumbling. Residual ethanol solvent might
make an interesting bang. Microwave baking is a fair test to see if
the body filler will handle 1KW of RF at 2.4GHz, but might be a bit
overkill for 200 watts at HF.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558