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Re: Coil form



Brad,

Sounds like it's performing Great(!) for a 6"/20" coil at the power
level you're running! Although the secondary Q could be increased
somewhat through the use of thinner-wall tubing, once you start getting
streamers off the top, the secondary Q is really dramatically
reduced/limited by the energy loss created in maintaining the sparks.
During "ring down" with no breakout, my secondary Q is about 160. If
I've got corona breakout, this drops to about 16 or less... You probably
wouldn't see any improvement by merely using thinner-wall material. 

A longer coil (24 - 30"), larger coilform diameter (8" or 10"), and
larger wire size will all help increase output. Try using about 900 -
1100 turns of #22 AWG on your next coil. If you're thinking about
winding another coil, I've discovered that the Heating and Ventillation
people in the Chicago area are beginning to use thin-wall PVC for heat
ducts in slab-poured buildings. One type is called "Bell-End Solid PVC
441 Heat/Air Duct System, type SDR81". I've used the 10" diameter with
EXCELLENT results (after pre-treatment with polyurethane and
post-coating with Behr Build 50 Epoxy). It's available in 10 foot
lengths in 6", 8", 10" 12" and 14" diameters, and is made by a number of
PVC suppliers. I've only seen the 10" stuff - its got about 1/8" wall
thickness. Check with your local HVAC people since it's not sold in the
major HW stores - they'll often have pieces left over from a job-site
that you can get cheaply (or better yet, for free!!)

Safe Coilin' to ya!

-- Bert --



Tesla List wrote:
> 
> >From bmcpeak-at-gte-dot-netFri Aug 30 21:56:09 1996
> Date: Fri, 30 Aug 1996 16:08:58 -0500
> From: Brad McPeak <bmcpeak-at-gte-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Coil form
> 
> Hello All,
> My latest coil secondary is wound on a 6.75 od. schedule 80 pvc pipe 20 inches
> wind length with #24 magnet wire, preped with poly before and after winding.
> Input is 12000 volts -at-120ma. With a variac I can get up to 44 inch
> streamers. I wound this with the thick wall pvc before I knew to use thin
> walled coil forms. My question is would it be worth while to wind another
> coil form of  plexiglas  and possibly use larger wire. I believe my primary
> could be tuned for these changes. Would the gain be significant? Thanks.
> 
> Brad McPeak