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Re: New Testing done and my 8" secondary



In a message dated 11/15/98 10:24:26 PM Pacific Standard Time,
tesla-at-pupman-dot-com writes:
          ---   snip     ----
<< 
 BTW: I just finished my 8" secondary:
 
 Specs:
 Wire: 0.85 mm = AWG "19.5"
 Wire spool weight before/after winding: 22lbs/12lbs
 i.d:0.850mm=0.0334567"
 o.d.:0.908mm=0.0357395"
 
 Secondary former:
 Total weight with wire: 21 lbs.
 Diameter:20 cm=7.8722"
 Total length:106 cm=41.75"
 Chosen winding length:82.85 cm=32.61"
 h/d ratio: 4.12
 Turns:940+1.2 (space wound from end of winding to end of former)
 Aprox wire length: 590m=1937 ft.
 DC resistance= 17.0 ohms
 Calc´d inductance: 37.86 mH
 Measured 35.6 mH
 (pretty damn close I would say)
 Cself=14.68 pF
 Ctoroid should be somewhere between 14.68pF and 58.73 pF
 So, I chose a Al dryer duct toroid with:
 Tube diameter: 4.271"
 Outer toroid diameter:31.8" 
 which gives me a Ctoroid of 30.78pF (about midway between)
 My loaded resonance frequency should be around 121 khz, which should be good
 for some long sparks. We will see, however. (Calcs where made with my
homebrew
 tc program)
 
 I glued a piece of 2mm thick copper plate (2" high x 4" wide) to the bottom
of
 the coil´s base. I soldered a nut to the copper, hammered the lower end of
the
 copper wire nice and flat and soldered this to the copper plate.
 
 The coil form was sanded thoroughly (wet and dry grit 60 to grit 150 in
 steps), dryed (3hrs total) coated with clear varnish (inside and out), wire
 wound, coated with 2 coats of epoxy resin (sanding in between coats), final
 smooth sanding (180 grit) and coated with 2 coats of clear varnish again. It
 looks pretty and it is as smooth as a baby´s butt. Now on with the
 work..................
 
 Coiler greets from Germany,
 Reinhard
  >>

Reinhard,

Sounds like a great secondary.  This coil will take a monster toroid if you
have a large enough power supply to drive it.  I would think a 6 to 8" radius
x  50" diameter toroid would not be too large.  What kind of supply do you
have?  Rotary gap?

Ed Sonderman