Re: Primary coil configuration

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Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>


If you run a 4 inch dia. sec coilform use a 15 or 20 degree inverted 
cone primary.  If running a 6 inch dia. sec coilform use a flat 
Archemedian (expanding) spiral.  Overcoupling is a big problem for 
most beginning coil builders and it generates multiple headaches like 
racing sparks, etc.  Keep it simple and it will work right the first time.

Use 1.3 to 1.5 x Cres for your MMC cap value and you will have a nice 
performer.  The 6 inch dia. coil will give you better performance.  V 
= -L x dI/dt.  Inductance, L, is proportional to the square of the 
radius of the coil so bigger is better.  Use #26 AWG for a 6 inch 
coilform and #28 AWG for a 4 inch coilform.

With a reasonably large toroid, ie, 20 x 5 or equiv. modern 
transmission line theory doesn't apply much to TC building.

Dr. Resonance

> Hi All,
>    I'm in the process of designing my first coil.  I'm a junior in 
> EE and it just caught my intrest while I was researching HV 
> transmission lines. I have a 15kV 60mA NST and I'm reading as much 
> as I can about the rest of the design before I actually buy/build anything.
>    My question is what is the difference between making the primary 
> wind outward away from the secondary opposed to winding vertically 
> keeping the windings all the same distance from the 
> secondary.  Also what does primary placement around the secondary 
> effect.  If I move the primary up to the middle of the secondary 
> what will that effect?
>
> ~Farmer