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Re: Primary/sec'y spacing for my big coil. (fwd)





---------- Forwarded message ----------
Date: Mon, 3 Aug 1998 17:14:19 -0600
From: "D.C. Cox" <DR.RESONANCE-at-next-wave-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Primary/sec'y spacing for my big coil. (fwd)

to: Larry Bu aka Clay

We use an 18 inch dia. tube (close to your 16 in size) and run the lowest
turn of the sec coil 2 1/2 inches above the primary coil and 1 3/4 inches
primary to secondary spacing.  This will give you the approx proper
coupling for fire-up.  3500 Ft. is good --- match it with a 0.1 MFD
capacitor on the primary and a good 34 x 8 1/2 inch dia toroid for a nice
12-14 ft. spark output at 15 kva input.

DR.RESONANCE-at-next-wave-dot-net


----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Primary/sec'y spacing for my big coil. (fwd)
> Date: Sunday, August 02, 1998 10:07 PM
> 
> 
> 
> ---------- Forwarded message ----------
> Date: Sun, 2 Aug 1998 17:11:59 -0500 (CDT)
> From: Larry Bud Melman <gasman-at-althea.a-line-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Primary/sec'y spacing for my big coil.
> 
> 	Hi all...
> 
> 	Finally got my coilform for my coil - using a 16 inch sonotube,
> sealed with urethane varnish, and going to reinforce with fiberglass
cloth 
> and resin, since I suspect 3500 ft of 14 gauge wire is *pretty heavy*...
> 
> 	Thinking about overall design, and when I was planning the primary,
> I realized that I wasn't sure how large I should make the space between
primary
> and secondary.  Don't wanna make it too small, but obviously will get
more
> spark from coil if I can minimize it... (I was planning a flat,
archimedes 
> spiral - sound good??)
> 
> 	I'm thinking about 2 inches space.  Whaddya all think??
> 
> 	Tentative specs of coil:  using 10 kVA PP, 23 kV (27 if using 280v
> input)
> 
> 	--height of windings 54 inches (800 turns) - sec'y inductance 73.01 mH
> 
> 	--Approx resonant freq 110.8 kHz
> 
> 	--Tank cap: 50 kV 0.05 uF ($375 at SurplusSales-dot-com - OUCH!!!!)
> 				  (geez - only gave $250 for my reconditioned
> 				   pig with non-PCB oil)
> 
> 	--Primary: using 1/2" (12.7 mm) copper tubing, 8 turns, should tune
> between 5 and 6.
> 
> 	--Sparkgap:  I'm blazing the trail with a Terry Fritz gap on this
> relatively high-power coil, planning 5 thousandths gaps times 50 or 60.
> I will do most anything to avoid the dreaded and feared RSG.
> 
> 	--Topload: beats the hell outta me.  I figure this thing will take a 
> toroid in the 48-inch range.  I have no idea where to get one.  Try some
> muffler shops maybe - I remember that thread.  They'd be awful skinny
though.
> Need a bigger X-section.  Probably end up with heating duct.
> 
> 	I'll be mighty disappointed if I can't get 10 - 15 foot sparks from
> this one...time to start wining and dining the neighbors...
> 
> 
> 						Clay   8-}