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Re: component sizing

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Esondrmn-at-aol-dot-com>

In a message dated 2/19/01 10:19:48 PM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:

 I am in the process of building my first coil and I have a few questions. 
  The secondary is 10.25" diameter on a PVC pipe.  It has about 916 windings 
 of 20GA wire.  For the Primary, I am planning on using 1/4" copper tubing 
 wound at a 15 degree inverse conical. the spacing between winding on the 
 primary is 1/2".  I have not "wound" the primary yet, but I was planning on 
 15 windings.  but I have notches in my supports for up to 17 winding. I 
 currently have 1 15/60 NST that I am planning on using to power it, but I 
 was going to try to get at least two more of them.
 Now for the questions.
 1.  From Ed Sonderman's Excel spread sheet I was planning on trying to get 
 a tank cap with a value of around .028 uF.  Does this sound correct, and if 
 so, what is the best way of obtaining the tank caps?  I have a limited 
 budget, but I am also trying to make a very nice looking coil.
 2.  I wanted to make a RSG.  I have access to some DC motors and 
 controllers, but I have seen a few places mention that an async-RSG is bad 
 news for NST's.  should I stay away from the DC motors?
 3.  I have some 1 1/2" acrylic that I was planning to use for the rotor of 
 my RSG.  I am planning on drilling and tapping 1/4-20 holes in it and using 
 threaded rod with acorn nuts on the ends for my electrodes.  is this a good 
 plan or bad?
 4.  RF chokes.  what are some good designs, and How do I size them?
 5.  what is the best method of constructing a toroid that would be large 
 enough for my coil?
 Thank for your help
 Tom Back

Quick reply:

.028 ufd sounds too small for a coil of that size - but I did not run the 
math.  I have a 6.0" diameter coil, admittedly with large toroids on top, and 
I use a .05 ufd cap.

I would definitely change the primary to flat v.s. conical and go with 17 
turns.  If I were building it, I would use 3/8" tubing.  A coil this large 
will probably see some serious power put into it some day.

Using nst power supplies, I would recommend starting with a RQ style 
cylindrical static gap.  It will work well and they are easy to build.

I built my first rotary gap as you are describing, with stainless steel acorn 
nuts for contacts.  You should use polycarbonate (Lexan) instead of acrylic.  
I think an acrylic rotor will come apart.

My toroids are made from 6" diameter corrugated plastic drain pipe, wrapped 
around a circular acrylic center disk and covered in clear plastic shipping 
tape then aluminum tape.  You can see them at my web site.

Ed Sonderman