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Sanity Check for me




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From:  Bert Pool [SMTP:bertpool-at-ticnet-dot-com]
Sent:  Monday, March 16, 1998 11:15 PM
To:  Tesla List
Subject:  Re: Sanity Check for me

> To:            "'Tesla List'" <tesla-at-pupman-dot-com>
> Subject:       Sanity Check for me
> Date:          Tue, 17 Mar 1998 01:29:02 -0600
> From:          Tesla List <tesla-at-pupman-dot-com>

> 
> ----------
> From:  baumann-at-proton.llumc.edu [SMTP:baumann-at-proton.llumc.edu]
> Sent:  Monday, March 16, 1998 3:45 AM
> To:  tesla-at-pupman-dot-com
> Subject:  Sanity Check for me
> 
> I have the opportunity to get a rather large diameter chunk of PVC,
> and am now dreaming of that monster coil. However, when I start running
> the numbers - I need a sanity check from some of you more familiar with
> this size beast:
> 
> What I have the chance for is some 18" diameter PVC, in about 6ft
> sections. Leaving my sanity out of the question for the moment, i
> thought this would be a rather nice coilform. 

Wild Bill Emery and I have recently wound a 19 inch diameter pvc pipe 
(18 inch inside diameter). 

> 
> Then I started running numbers: 
> If I use 18AWG wire, WinTesla tells me that at 44inches, I would
> have an unloaded frequency of about 77Khz, at an HD ratio of 2.35
> This is about 1000 turns and about 5000 ft of wire.
> 
> If I use 22AWG still aiming for 1000 turns: ratio drops to 1.5 (27")
> and frequency to about 70Khz
> 

Because of the large size of the pipe, we chose to go with 14 gauge 
wire.  18 would work, 22 would be way too small for a form this size.

> 
> 
> 
> I would assume the 18AWG is required to keep the resistive losses
> down.

Yes, I'd suggest 18 as a minimum, 16 or 14 would be better.  I like 
the larger gauge wire.

> 
> Throw a 6"x36" toroid on there, and the frequencys drop to the
>  40khz range, and the cap size jumps from about 0.03 to 0.07 for 22awg
>  and from 0.02 to 0.05 for the 18AWG, operating frequencies drop
>  into the 40Khz range
> 

We've run a 8 inch by 62 inch top, and it was *way* too small!  A 6 
inch by 36 inch is woefully small.  We're planning on an 18 inch by 8 
foot top for this monster - as soon as we can afford the materials 
cost.  Of course it takes a lot of power to break out of a top this 
size, so we'll be cranking it up.  We started with 0.12 ufd cap - 
we're going to try to scale that back to 0.06 ufd, exactly in the 
range you're forcasting.

> Primary would be close to 100ft of tubing if I used 1/4"

Again, scale it up - I'd recommend 1/2 inch tubing.  And you'll want 
15 turns so you have plenty of tuning room.

> 
> Would I be wasting my time? And if so, is there a use for this 
> large PVC that I don't see? [It's going in the trash unless I find
> a use..]

You are looking at 8 to 15 kilowatts to run a coil this size.   A 
pole pig and a really stout tungsten rotary spark gap are 
necessary, along with heavy duty ballasting.  I'm always amazed at 
how much money you end up spending before you get something this size 
up and running.  We've gotten ten foot sparks with the five foot top, 
and then we had a secondary strike which shorted two turns.  The 
newly repaired coil should push out way beyond 10 feet!

Michael, you can see our Wart Hog at http://www.ticnet-dot-com/bertpool.

Never turn down the chance to get a big pipe like this.  Just be 
prepared to spend a lot of time and money to build and run it.

Bert Pool

> 
> 
> 
> -- 
> --
> Michael Baumann  Optivus Technology Inc.|Loma Linda University Medical Center
> San Bernardino, California. (909)799-8308 |Internet: baumann-at-llumc.edu
> 


Bert Pool
TCBFW
bertpool-at-ticnet-dot-com