Re: The 64k$ Question

>From tahoetom-at-best-dot-comThu Jun 20 22:18:04 1996
>Date: Thu, 20 Jun 1996 18:00:19 -0700
>From: tom renko <tahoetom-at-best-dot-com>
>To: tesla-at-poodle.pupman-dot-com
>Subject: The 64k$ Question

Tom, In response to your questions...

>          Hi, Guys and Gals..............

>          I am building my second generation Tesla coil. My question
>          to you,who probably have a lot of experience with this, is:

>          What type of spark gap would you recomend for the following
>          Tesla coil (ie. airblast, series w/air,etc.) I will experiment
>          with everythig else, but I really don't want to waste a lot of
>          time with this element.........

I wouldn't consider time investment in trying to come up with a 
superior quenching gap system for your Tesla coil a 'waste of time'.
If you want a superior performing system, you will probably have to 
establish a design,  build it, test it, and refine it, etc., yourself.
If you are willing to settle for a quickly obtained but mediocre system, 
there are several sources of pre-made or kit coils offered on the 
market.  If you want a medium to larger size killer coil that 
operates near or at state-of-the-art performance levels, there are a select 
few suppliers out there who will craft you one, myself included.  For 
the best, be prepared to spend big bucks.

In the power range you are proposing (1.8 kVA), if it was that simple I'd say
go with a fixed, multigap system with large flat parallel surfaces 
blown/cooled by low speed air from a hefty squirrel cage blower.  
But, see my comments to follow. 

>          Xfmr: Two 15kv neons in parralell (60 m.amp ea.)
>          Cap: 20kv, .025 mfd (CP unit), due in one week
>          Primary : 14 turns, 3/8 copper, 30 deg. spiral
>          Secondary: 6" acrylic, 22 ga. magnet wire, 875 turns
>          Chokes: "Winging it" (maybe recent TCBOR, D.C. Cox ???)

I think to drive that large capacitor properly you need to use three, 
15kV-at-60mA neons.  This is the area (2.4 kVA) where you get into a gray area 
where a straight fixed gap, unless carefully designed, may not quench properly,
and where a rotary is known to work well.  You see its not that simple. 
Complicate the issue further by the reports made by some experienced coilers
that rotary's blow up neons, and your decision becomes even more 

I personally have no real experience with rotary break/neon operation so I
cannot comment usefully on this configuration.

I'll take a stab at a recommendation.  Make a multi-fixed gap (maybe 
7-9 gaps) that has a hole down the center where high pressure air from a vacuum 
cleaner blower can be applied where it will escape between the gaps.  
Make the gap system out of 1.5 to 2 inch diameter copper tubing with 
a thick 3/8" to 1/2 inch wall thickness.  Face the gap surfaces on a 
lathe and polish them smooth.  Put an  insulating air hose from
one end of the gap system off to your blower.  Seal the other end to 
allow pressure to build where it will only escape through the gaps.  Operate the
blower from a variac so you can optimise air flow and thusly gap performance.
You will not likely need full blast.  Go with 3 identical neons, not 2.

If you would like to go with a pair of my proven Mega-Henry brand RF chokes, 
please e-mail me off list.
These are  my recommendations.  Good luck!

>          Any help on the spark gap issue would be most appreciated.
>          I should throw the switch in about two weeks,and will be
>          eager to share my results with you......

>          Tom Renko  (The Amp Man)

Happy coiling, unlimited electricity, basic food and requisite sleep,