spark gap/ primary coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Michael Ong" <omenowner725@xxxxxxxxxxx>

hello, i am planing to use a TCBOR style spark gap but was wondering 
what the advantage was of having it in the circular PVC pipe instead 
of just a flat sheet of plastic with large fans blowing across it. it 
seems like construction would be difficult to get the spacing correct 
inside a tube like that. also, my coil is going to be a 6000kv  with 
a secondary of 4.25" diameter  1700 30 awg wire (22 inches tall) for 
the pirmary using 1/4" copper tubing 1/4" spacing in a flat spiral my 
java tc simulations say that i will need about 52 feet of copper (18 
turns). I dont think i want to spend the $100+ on just the pirmary so 
i am thinking about going with coax cable. my question then is: is 
there a way to adjust the pirmary easily using coax? or is the easy 
shorting clip used on the copper tubing the reason why most use that?
thanks again for all your help, its really getting me through my 
first tesla coil experience.

_