Re: Structural support, was: oil dielectric

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "rob by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rob-at-pythonemproject-dot-com>

Tesla list wrote:
> 
> Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<davep-at-quik-dot-com>
> 
> >>Absolutely! And a glazed surface would be preferable to reduce
> >>absorption of potentially conductive material. Ceramic has been used for
> >>high power RF coil forms for almost 100 years. The downside to using
> >>ceramic is that it's significantly heavier and more brittle than PVC.
> 
> > You are correct about the ceramics being much heavier and more brittle. I
> asked
> > questions about useing 300 series  (non-magnetic) stainless in another
> > post.This would allow for a thinner coating of ceramic. Reply posts
indicate
> > metals would absorbe energy in the form of heat causeing losses in the
> coil, as
> > well as expansion and contraction in the steel tube. I would not see any
> > problem with using pvc coated with ceramic
> 
>         Why coat the PVC with ceramic?
>         What benefit or purpose is obtained?
>         As many have pointed out (and demonstrated) PVC (or HDPE) is
>         fine, as is, as a form/support.
> 
>         When dealing with 10s of KW of RF, in the vicinity
>         of hot tubes, Ceramics have a place.  Or did.  Ceramics
>         were used when HDPE (etc) did not exist.
> 

You can get some relative indication of RF losses for a material by
putting it into a microwave oven.  I did this once to dry out a piece of
ABS (for my swimming pool :) and did not notice much heating.  Rob.


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