Re: Coil Doesn't Fire

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bart Anderson" <tesla111-at-sbcglobal-dot-net> 

Hi Jim,

I agree that the problem sounds like a charging issue. However, I also note 
your coupling is rather low (0.115). While modelling your coil, I noticed 
the highest coupling possible was 0.148 with your current setup. This was 
done by lowering the secondary, but I ended up 7 inches below the primary 
just to get to the 0.148 value.

Obviously, 7 inches below the primary lowest turn is ridiculous, especially 
for an inverse cone primary. This is all due to the very wide primary to 
secondary clearance of 3.25" when the secondary bottom turn is even with 
the bottom primary turn. You can help out the coupling a great deal by 
adding 2 turns within the inner primary so that the primary inner radius 
ends up at 3.5". Your coil should then tune in at 261 kHz at turn 14.25, 
and your coupling will be up around 0.144 if the bottom secondary turn is 
even with the inner primary turn (1 inch clearance). Your are then in range 
to make coupling adjustments to benefit your particular coils behaviour. 
Also, you will have 2 outer turns available for tuning adjustments should 
you change toploads or other misc. improvements.

I'm not saying this is your current problem, but it is something which you 
will want to correct sooner than later. In the mean time, a description of 
what you see and hear at the gap would be helpful to all.

Take care,
Bart B.

Original poster: JBarrett-at-trumbullcorp-dot-com

>>Hey I bet no one has had this problem. Just kidding!
>>
>>Transformer:
>>12,000 Volt 30 ma
>>
>>Caps
>>Panasonic ECW-H 0.0043uf +- 3% W.V. 1500 VP-P 2500 VDC with a 1 megaohm
>>bleeder resistor across each cap. 8 in series 12 parallel.
>>
>>Secondary
>>21" of 22 guage wire on a 4 1/2 inch PVC Pipe
>>
>>Primary
>>14 turns of 3/8 copper tubing mounted on 3/4 inch plastic risers set at 30
>>degrees. The inner radius is 5 1/2inches.
>>
>>Torid
>>22 inch major radius of 4 inch flexible dryer duct mounted on aluminum foil
>>covered 1/4 inch plywood.
>>
>>Spark Gap
>>Air cooled at 25 psi
>>
>>Grounding
>>2- 4 foot ground rods driven into ground and soaked with h2o.
>>
>>I believe my caps are the major source of the prolem however someone
>>pointed out that my transformer is a little small too.
>>Any other thoughts?
>>
>>JIM