RE: Mica (and turning)

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Gary.Lau-at-compaq-dot-com>



-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, March 09, 2001 10:01 AM
To: tesla-at-pupman-dot-com
Subject: Re: Mica (and turning)


>Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<bigfoo39>-at-telocity-dot-com>

>> I found a guy the other day that makes little parts for "something" out
of
>> mica.
>> Beats me what he uses the stuff for, but he has it in HUGE quantities.
>> If i stuck a long bit on the lathe, made it round and then drilled out
the
>> center REALLY carefully with a press, would that work as a secondary coil
>> form??
>> >From what I know, Its kinda brittle, so it'd probably go smaller than
4in
>> by 2/3ft....
>>WOW!!!   mica in that quantity??

>i dont think that mica as a secondary will increase performance that much
>more. just
>thinking....  why even drill the center out?? Mica has a whole lot better K
>than air anyway
>;)  .
>
>Scot D

If said mica is in a cylindrical shape, I'm guessing it's probably
reconstituted mica, like wood chips that make up particle board, with some
unknown binder added to it to keep it together.  The electrical properties
of this binder would need to be considered.

A "k" value refers to the dielectric constant - the factor that a
capacitor's capacitance value using this material for a dielectric would be,
over an identical cap using a vacuum for dielectric.  This k factor implies
nothing about what dielectric losses would occur, and in a capacitor, the
dielectric loss factor is what determines how suitable, loss-wise, a
material is for use as a capacitor dielectric.  But in the context of a
secondary form, it's not clear that there's a significant an e-field where
dielectric loss in the form would occur.  The magnetic field is probably the
dominant thing that the form sees, and I'm not sure what physical property
is a predictor for losses in a magnetic field.

Lastly, no one has ever shown that the use of exotic materials in secondary
forms is *measurably* any better than common PVC pipe, at least in spark gap
based coils.  

Gary Lau
Waltham, MA USA