Re: spark gap/ primary coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Just Justin <rocketfuel@xxxxxxxxxxxxx>


On the subject of 1/4" copper tubing, I wonder if any here have
recommendations for a good moveable clamp that fits the 1/4" tube
well?  My current clamp has some steel in it and tends to get
a bit too hot to touch after just a little while ;)

Justin




On Wed, Feb 22, 2006 at 09:47:59AM -0700, Tesla list wrote:
> Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
> Hi Michael,
>
> Welcome to the list and to coiling ;^) First of all, you are NOT
> going to be delveloping 6000 kV (that's 6 megavolts!) with your
> coil nor is anyone else on this list for that matter! 600 kV would
> be a closer guestimate although that's still probably high by a fac-
> tor of 2 or 3 for an average sized NST driven, spark gap coil.
> The alternating currents in the tens or hundreds of kHz can pro-
> duce spark lengths vs voltage that are much higher than the
> standard DC sphere spark vs voltage rating.
>
> The 1/4" copper tubing should not be that expensive at your
> local home improvement store's (Home Depot or Lowes) plumb-
> ing department. I would think that you should be able to obtain
> (2) 50 ft rolls of it for under $50. I think most knowlegable coil-
> ers are going to tell you that coax cable is NOT a good choice
> for the primary coil conductor. In operation, it will carry some
> very high peak currents (in the hundreds of amps) and the fine
> outer braiding of standard coax cable is not suitable for carrying
> these immense currents. OTOH, copper tubing is indeed well
> suited for this purpose and is the usual conductor of choice for
> most coilers' primary coils. Also, as you said, the bare copper
> tubing renders multiple tuning much simper than with insulated
> wire.
>
> Good luck with your coil,
> David Rieben
>
> ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Wednesday, February 22, 2006 8:57 AM
> Subject: spark gap/ primary coil
>
>
> >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.
> >_
>
>