RE: spark gap/ primary coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

A PVC tube is usually used simply because it's easier to efficiently
couple the air from a circular fan to a circular tube.

Hmmm, 6000kV, or 6MV, from a 22" long secondary?  How much did you pay
for those plans ;-)

Don't use coax cable for a primary conductor.  Stranded, and in
particular braided conductors are very lossy due to skin effect.  Yes it
seems counter-intuitive since there would appear to be MORE surface area
in a stranded conductor, but the problem is that the current only wants
to travel on the OUTER strands, and will attempt to flow from inner to
outer strands to do so, through whatever high resistance tin plating and
surface oxides it encounters.  50 feet of refrigeration tubing should
cost nowhere near $100, but if it's still too rich for your budget, just
use #12 solid wire from Home Depot.

The ease of tapping 1/4" copper tubing is probably the best reason to
use it.  It also will look a lot better and hold its shape better than
50 feet of wiggly stripped copper wire.

Regards, Gary Lau
MA, USA

>
> Original poster: "Michael Ong" <omenowner725@xxxxxxxxxxx>
>
> hello, i am planing to use a TCBOR style spark gap but was wondering
> what the advantage was of having it in the circular PVC pipe instead
> of just a flat sheet of plastic with large fans blowing across it. it
> seems like construction would be difficult to get the spacing correct
> inside a tube like that. also, my coil is going to be a 6000kv  with
> a secondary of 4.25" diameter  1700 30 awg wire (22 inches tall) for
> the pirmary using 1/4" copper tubing 1/4" spacing in a flat spiral my
> java tc simulations say that i will need about 52 feet of copper (18
> turns). I dont think i want to spend the $100+ on just the pirmary so
> i am thinking about going with coax cable. my question then is: is
> there a way to adjust the pirmary easily using coax? or is the easy
> shorting clip used on the copper tubing the reason why most use that?
> thanks again for all your help, its really getting me through my
> first tesla coil experience.
>
> _
>