Re: Coil Frustration

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

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

CJ, 
 
After reading your specs, I have a few thoughts:

1)  Your spark gap is too wide.  You will surely kill your trannies soon with 
such a wide gap.  The total spacing should be on the order of 0.25 inches at 
the most for your OBITs, and likely it should be closer to 0.20 inches.

2)  You have a large coil and it probably would like to run better using, say 
12-15kV and 60 - 120 ma.  I have an 8 inch coil that works well with 15/120.

3)  You did not say whether your caps were in series or parallel.  If in 
parallel, you need at least one more turn on your primary to get it tuned.  
You could wind a small coil of tubing of about 4 inch diameter and about ten 
turns and placing it in series with your primary coil just to see if it 
brings it in tune for you.
    If your caps are in series, then you need at least 15 turns to get it 
tuned.  Both of these numbers are based on what I guessed is a 4 x 16 toroid 
on top - which you should replace.

4)  I haven't been on the list for about a year, but I would guess that you 
do not really want chokes for your transformer protection.  Unless things 
have changed, I would guess that Terry's capacitor/safety gap scheme is the 
best protection still.

   You stated that your primary is made from 3/4 inch tubing, but in the 
picture, it appears to be 1/4 tubing with 3/4 inch spacing.  I hope I am 
correct, because that is what I used in the calcs.

Hope this is helpful,
Mike