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which disease?


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From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent:  Thursday, March 19, 1998 12:46 AM
To:  Tesla List
Subject:  Re: which disease?

Hi Arwin,

> From:  solva-wijnschenk [SMTP:solva-at-xs4all.nl]
> Sent:  Wednesday, March 18, 1998 6:20 PM
> To:  bert pool; DR.RESONANCE-at-next-wave-dot-net; john freau; richard hull; tesla-at-pupman-dot-com
> Subject:  which disease?
> 
> Dear All, I need some help.
> 
> I wound a coil (diam. 4.33", height 33.66") with .35mm wire (AWG 28??)
> and a total secundary resistance of approx. 155 ohm. I thought that
> these 790 meters from 2290 turns would give me resonance at 94,8 kHz.
> Why not???

Because it is wound up as a single layer coil and the distributed L 
and C parameters of the wire have been severely modified.

> Everybody talks about 3:1 ratio but that means with 10" diam
> ->30"height, doesn't it. How do I get 1000 turns in so little height.
> Can I take a form with more height??

Sure. The h/d = 3 thing is a compromise which gives a balance between 
inductance and Q for a closewind.

> I now get breakouts (>20") at half of the form, distroying my turns. I
> am using a cap wound from 2.5mm thick red plastic (don't know the
> material) 2 plates from about 20 cm widht and 7 meters long. Primary is
> 7.5 turns of .5" copper tube, gap=single .5", toroids vary. Best
> sparklength I get (don't understand!!!) with a very small toroid! Supply
> is a 10 kv 10kva plate transformer and a variac.

Either one of two things is happening when the windings flashover - 
either your primary energy is such that it generates too high a 
voltage in the secondary or it is marginal and corona leakage is 
finishing the job. If the primary is a helix, forming it into a flat 
spiral might effect a cure as long as the voltage across the 
secondary isn't excessive.

> is it wise to build a new coil with 8"diam and what height and number of
> turns should it have??? What wirediam??? I am thinking of using wire
> used in mainssupply (2.5 mm2). at least is low resistance. What am I
> doing wrong?

I'd go for an h/d of around 3 - 4 for that coil. For an h/d of 4 
(better from a voltage and wiresize point of view), I'd use wire 
around 1.2mm diameter for a closewind. The 2.5 would be OK but one of 
the aims is to get frequency down to allow plenty of leeway in the 
primary design.

Be interested to hear what others would do.
Malcolm

  > Please advice 
and thanks, > 
> ARWIN, Holland
> 
> 
>