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RE: CAP DESIGN (FWD)

 * Original msg to: Kukkonen-at-snakemail.hut.fi


 KU> On Thu, 22 Dec 1994, Richard Quick wrote:
 
 > I build polyethylene caps, and there is no diffusion through 
 > this plastic by the oil. PVC is slightly permeable.

 KU> What I meant was that the oil will diffuse through the tank 
 KU> which is made of pvc, right?

Yes, but practically it is not a problem. I have had PVC tanks 
full of mineral oil for 2 - 3 years and have had no problem with 
seepage or diffusion. The transformer oil is a lighter grade of 
oil, so some slight seepage might be possible after a few years. 
You could seal the inside of the tank after construction with 
two-part epoxy paint.

 Ku> Could the tank be made of acrylic plastic as well?

I would use this material for secondary coil forms before I 
would spend the money to use it for a capacitor tank. Seal a
PVC tank before filling with oil if you are worried about 
diffusion.

> Talking about primary coil parameters... RQ 

 KU> If memory serves, you mentioned about using an angle of 30 
 KU> degrees.. Is this linearly from the base-level to the end 
 KU> of the "bend"?

Hmmm, how best to describe this without pictures... Bear with me.
The plastic wedges I was describing earlier give the angle of the
slope. The slope is linear from the inside turn to the outside turn.
Each turn of the primary is raised by the same amount.

BTW, the pipe we use for primaries here is a "soft" grade of 
copper, commonly called "refrigerator tubing", it is sold in rolls. 
The other grade of copper pipe is "hard", it does not bend well,
and it is sold in straight lengths. 
 
 KU> About the bypass-caps : could one not made them using glass
 KU> as the di-electric material?

Yes, I covered this with Mark Conway too. Glass, because of it's
high RF dissapation factor (high loss) is ideal for construction
of bypassing capacitors to be placed in the HV feed line to the
Tesla Tank circuit. 

 KU> I just acquired about 25 cm of 30mm diameter brass-rod that 
 KU> weights about 1,6 kg.. I'll soon make a spark-gap similar to 
 KU> your airblst- spark-gap.. 

Hoo Boy, another air-blast gap in the making... Those plans have
resulted in quite a few of these gaps.

I did make a modification on this gap later that cut down on the 
air required yet maintained the un-surpassed performance. I drilled
a hole through the face of both electrodes, and plumbed in the air
from the back. This method injected two opposing air streams into
each other right in the center of the gap. The quenching was still
excellent, but it used only 25% of the air previously required.

 Ku> Thanks for your advices! Merry christmas!

Thank you, I hope I have been of help!
Richard Quick  


... If all else fails... Throw another megavolt across it!
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