Re: Rotary Spark Gap.

From: 	D.C. Cox[SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: 	Sunday, December 07, 1997 12:19 PM
To: 	Tesla List
Subject: 	Re: Rotary Spark Gap.

to: Josh

Mounting the aluminum disks in "an electrically isolated configuration"
might be more of a problem than you suspect.  Insulators have the unique
property of high voltage "tracking" across their surface -- sometimes up to
10 times the normal distance -- and this depends greatly upon the relative
humidity, dust, and other factors.  The HV RF currents might try to track
across your insulator and strike the motor shaft, ie, ground.  I still
suggest using G-10 as the rotor with axial 1/2 dia. brass rod and tungsten
electrodes as the best answer.  Aluminum, like steel, is also a relatively
poor conductor of high frequency currents and your peak current will suffer
if you use the conducting properties of aluminum for your RSG.

HV insulator tracking is a problem and it is worse with RF currents.


> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
> Subject: Re: Rotary Spark Gap.
> Date: Sunday, December 07, 1997 12:13 AM
> From: 	Joshua Resnick[SMTP:seraphim-at-WPI.EDU]
> Sent: 	Saturday, December 06, 1997 10:57 AM
> To: 	Tesla List
> Subject: 	Re: Rotary Spark Gap.
> Mike wrote:
> > >I have concerns as well for the melting temp of Plexiglas.    I'm
> > going
> > >to put together a G10 disk as soon as I can get my hands on some.
> > The comments on fibre discs earlier in this thread reminded me that I
> > had some 3mm thick PCB laminate, which ought to be pretty good. A few
> > layers of this (with the copper etched off, or partially etched to act
> >
> > as a heat spreader), or normal 1.6mm laminate screwed/glued together
> > should make a nice strong disk with good insulation and temp
> > performance.
> >
> > >*Does anyone know of a good supplier of 1/2" G10 preferably already
> > cut
> > >into a disk shape?*
> > Why not cut roughly to size (even square), mount on the rsg motor and
> > use the motor itself as a lathe to cut the circle shape - no centering
> >
> > problems!
> Mike,
> I ordered 2 12" x 12" x 1/8" aluminum plates.  I'm going to fabricate
> two identical disks from these and mount them in an electrically
> isolated configuration from the shaft of my motor.  Do you think this
> sounds like a decent plan?
> -->Josh