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Re: Yet another newcomer, and from Sweden this time


From: 	Peter Electric[SMTP:elekessy-at-macquarie.matra-dot-com.au]
Reply To: 	elekessy-at-macquarie.matra-dot-com.au
Sent: 	Saturday, August 30, 1997 4:55 AM
To: 	Tesla List
Subject: 	Re: Yet another newcomer, and from Sweden this time

Tesla List wrote:

> From:   Per Niva[SMTP:pna-at-pp.gellivare.se]
> Sent:   Wednesday, August 27, 1997 2:07 PM
> To:     Tesla List
> Subject:        Re: Yet another newcomer, and from Sweden this time
>
> Peter Electric wrote:
>
> > I am running a 900W coil (15Kv 60Ma) and I have much the same
> > setup working fine. A couple of hints though, I found a 6" coil
> > performed much better than a 3.5" so I would try for a bigger
> > diameter if possible. If you can't get PVC plumbing pipe easily,
> > try rolling a few layers of cardboard and varnishing heavily. Or
> > you might be able to find cardboard concreter's forms for making
> > posts.
>
> I think I can find a 6" PVC pipe. But, people seem to say PVC is
> bad? I reckon due to RF loss. Why is PVC bad as a coil former? If
> I cover the PVC with a 2-component polyurethane enamel, is it still
> bad? Does the pipe (or it's water content?) act as a core to the
> coil, or is it just the electrical properties that matters?
>
> Currently I have this 3" secondary wound on a HDPE pipe. Would the
> 6" PVC coil be better? (I guess so...)
>
> > The safety gap is not critical, just use two brass 1/4" bolts.
> > My main gap consists of two adjustable brass cylinders with
> > flat ends mounted in a plumbing pipe, with a good airblast
> > from a fan.
>
> Everybody seems to use brass, or the big shots use tungsten.
> Is the material important, and then what are the criteria?
> Good conduction, high resistance to wear due to the sparks?
>
> My current gap electrodes is steel. That is _bad_ I guess?
>
>
> > Hope this helps some.
>
> It sure does.
>
>
> > Cheers,
> >
> > Peter E.
>
> Hälsningar,
>
> Per
>
> ----------------------------------------------------
> pna-at-pp.gellivare.se                 +46 (0)970 20976
> "Beware - the world will never be the same again..."

My first 3 1/2"coil was made of Perspex (Plexiglass) and the second 6"
from PVC but the 6" is still a much better performer. Although PVC is
lossy, in the secondary I think it matters very little. If you have a
choice, use the thinnest walled PVC you can get and make sure you dry it
first by keeping it in a warm place for a couple of days. Richard Quick
has a very detailed set of instructions for winding secondaries, I
believe you can download it from Chip Atkinsons home page. By the way, I
think the great majority of people on this list use PVC secondaries very
succesfully.

For sparkgaps, tungsten is good for coils running big input powers
because of its low wear rate. Otherwise for smaller coils like ours,
brass is fine.

Cheers,

Peter E.