Re: Tuning Questions

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

Original poster: FutureT-at-aol-dot-com 

In a message dated 2/27/04 6:19:13 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

> >The software is telling me that I need 15.75 turns on the primary, I
> >currently have 14.5. Before I add the extra wire and start adjusting I was
> >wondering how sharp of a "Q" is a tesla coil circuit? I would not expect
> >it to be very narrow. In other words I don't expect to see much difference
> >adding or removing one turn.


JC,

Your coil looks good.  The potential is there for good performance
because you used 1400 turns.  Do you have some way to tap
the primary to tune the coil?  If you are tuned right at the end,
and have no tap points, then you have no way of knowing if it
needs more turns or less.  You also have no way to know how
far from optimal the tuning is.  You can remove some insulation
from various spots on the wire and lift up a loop and tap to it to
try fewer turns.  Some more wire can easily be soldered on to
add more turns.  I recommend tapping at at least 1/2 turn
intervals to find the best tune point.  A change of 1 turn can
make a tremendous difference depending on the accuracy
of the original tune point (tap point).  The coil must be tuned
outwards until the spark begins to decrease, to be sure the
best point has been passed by.  You can decrease the toroid
diameter up to a point, but if the toroid is too small it will hurt
the performance.  Rather than shinking your existing toroid,
you may want to make an entirely new smaller one so you'll
have the option of easily switching toroid sizes.

Regarding the achievable spark length for your coil, I think
34" sparks can be produced by using a simple series multiple
gap and by feeding the NST with 140 volts.  I'm not sure how
much spark length will be lost by using 120 volts.

John