Re: [TCML] Tuning a new coil (sparkgaps)

[b alex pettit jr <a_pettit_jr@xxxxxxxxx>]

Hello Bart,
   
  That should be 24 inch streamers. I'd really be dismayed with two 
  inch sparks. 
   
  I reworked the spark gap again yesterday. 
  It is a ring of 10 each, 1" copper pipe segments in a PVC pipe with a pair  of  5 1/4" fans sucking. 
   
  To get an accurate gap,  I used, first tape, then tried fiberglass 
  shims. In each instance, the sneaky E-field found it advantageous
   to track along the surface of that material, quickly carbonizing
   it and shorting out the gaps. 
   
  I spent many hours turning each copper tube
  on my lathe to create 1/2 deg tapers. The effect is that the
  end are now 0.015" in dia smaller than the central portion. 
  Hopefully, this will force the sparks to stay centered and
  away from ( what will be ) the Teflon tape ! I will also
  wash all down with alcohol to remove any fingerprint residue-
  that may have been an added problem.
   
  I'm also pondering trying some design with tungsten surfaces.
   
  I will upload some photos if I ever get it working.
   
  Thanks,
  Alex P
   
  Hi Alex,

  Your streamers are 2"? Is that a typo? 2" is not good. Your gap is probably the biggest area needing improvement. I would go after that before messing with the top terminal. I have had good luck with multi-segment gaps. Not the kind laid out flat, but mounted in a pipe for air control. Lot's of air is important. I personally like large tubes and not the small 1/2" type. I really hate static gaps using tubes that are laid out flat on a slab. I've never had good performance with those. 


Here's a pic of the gap I use on my 4.5" coil (ignore the brass electrodes in front, they sucked!). 
http://www.classictesla.com/photos/ba45/s2752.jpg

 

Take care,  Bart      
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