Re: Racing sparks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi Tom,

Yes, sorry. I meant increasing the distance between coils to reduce 
coupling (this isn't the first I stated proximity backwards). Since you 
used the phrase "flattening the primary", I assume you built an inverse 
cone. That would explain the higher k value. Yes, a flat primary will do 
the job nicely.

Take care,
Bart

Tesla list wrote:

>Original poster: Thomas <tom-at-pwrcom-dot-com.au>
>Bart, I've already removed an inner turn, this solved the problem of primary
>to secondary arcing, but I do not want to do it again, it was quite a chore.
>
>JAVATC predicts that raising the secondary about 30mm will have the same
>effect on coupling as flattening the primary, so I'm going to try that first
>(new k=0.13).
>
>I thought "Increasing the proximity between coils" would increase the
>coupling? Did you mean decrease?
>
>Thanks for your help,
>
>Tom L.
>
>Original poster: Bart Anderson <classi6-at-classictesla-dot-com>
>
>Hi Tom,
>
>0.17 is quite high on a 2-coil system. Increasing the proximity between
>coils is my preference. Because you have a lock-in setup for the
>secondary,
>an alternative to increase the proximity between coils is to remove 1
>turn
>on the ID of the primary.
>
>Take care,
>Bart
>
>Tesla list wrote:
>
> >Original poster: "Tom Luttrell" <tom-at-pwrcom-dot-com.au>
> >I rebuilt my blower spark gap,
> >http://www.webclot-dot-com//high_volt/images/toms_new_gap_2.JPG
> >
> >This has allowed for a considerable improvement in airflow and streamer
>
> >length. I'm now getting the occasional hit to the strike rail,
>something
> >that did not ever happen with my previous gap.
> >
> >This new gap just fires at a setting of 8mm with only the NST
>connected,
> >as opposed to about 5 to 6mm for my previous gap. I put this down to
>the
> >sharper rim of the pipefittings as opposed to the flat brass rod face
>of
> >my first gap (http://www.webclot-dot-com//high_volt/images/toms_gap2.jpg).
> >
> >Unfortunately it's too good. After about 5 to 10 seconds of operation I
>
> >start to see racing sparks on the secondary.
> >
> >My primary is an inverted cone (30°) and the coupling is probably a bit
>
> >tight (JAVATC calculates it to be 0.17).
> >
> >The way I see it I have the following options:
> >
> >1) reduce input power via my new yet to arrive variac
> >
> >2) reduce the spark gap (and hence firing voltage)
> >
> >3) cut down the primary supports so it becomes a flat pancake coil
> >
> >4) raise the secondary height.
> >
> >Options 1 and 2 have the advantage of being easy but would negate the
> >recent gain in streamer length.
> >
> >Options 3 and 4 would require some major rework, including
>modifications
> >to the mechanical method by which a 1/4 turn twist of the secondary
>locks
> >it in place.
> >
> >I'd be interested in reading any thoughts you may have on this matter.
> >
> >Tom.
> >
> >
> >
> >
>
>
>
>