Re: New Primary Design

Hello Nick and list

I use a double stacked primary just like this on my 5kVA, 200mm coil! I use
20mm for the acrylic. In NZ, 3/8OD copper automotive tubing comes from the
shop (Mitre 10) already wound into this form (with the pipe ends at the
outside of each stack, winding inwards and joining at the inside of each

I am using this approach because it keeps the primary compact, primary
inductance high, and it looks slightly unusual. I'm still tinkering with
this system, but initial tests look very promising.

Safe coiling,

Gavin Hubbard

At 06:24 PM 9/13/99 -0600, you wrote:
>Original Poster: "Steve Young" <youngs-at-konnections-dot-com> 
>If you look in the archives, you can find info about more compact
>primaries.  See one example quoted below:
>Malcolm stated in part:
>>I have finally done a definitive test of 
>>a stacked spiral primary and it works extremely well. The something 
>>for nothing bit is that if you built the bundle of copper tube I 
>>bought into a single flat spiral you might scratch 50uH from it. 
>>Arranging it in two layers with a sheet of acrylic in between brought 
>>it close to 80uH simply by making use of mutual inductance. The 
>>tubing is 3/8". It came as a 2- layer coil that spiralled in on one 
>>layer then back out again on the next. If you lifted the outer turn on 
>>one side it would form what looked like an hour-glass.
>As I recall, there is more info on the double flat spiral primary in the
>archives.  It might be the way let you use a primary with a smaller
>> From: Tesla List <tesla-at-pupman-dot-com>
>> To: tesla-at-pupman-dot-com
>> Subject: New Primary Design
>> Date: Friday, September 10, 1999 5:37 PM
>> Original Poster: NickandSim-at-aol-dot-com 
>> Hi All,
>>          My next coil has just grown from 2.4kVA 8"dia. to 4.8kVA 13"dia.
>> Unfortunately I now do not have room for the primary that such a large
>coil ( 
>> 147cm high 32.5cm diameter) would need using the normal design ruled for 
>> small coils.  Darn.  I wondered if any of you with experience in coils of
>> this size, Dr. Rez etc., would be able to give me any advice on the
>> primary I can get away with, as the rule of secondary length = primary
>> does not seem to be so rigorously used on big coils as on little ones. 
>> wire is 0.6mm diameter copper magnet wire.
>> Also just a note to everyone who came forward with caps for sale and/or 
>> advice, thanks guys.  I now have an 8F 10kV cap on its way to me.
>> BTW:Thanks to Bob Golding for the xfmr core, boy is that one big limiting
>> inductor.
>> Sooo this is your second coil............
>> Nick Field