Re: Tuning Questions

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

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

Hi Joe,

I believe you are out of tune.  I don't know what your major diameter is
currently and reducing the major diameter can bring it into tume, but doing
so may reduce the potential spark length.  I currently have a 12KV 30ma NST
running 9.7nf, 16T primary (one turn more than the program says to account
for streamer loading), 3.5x18 1523 turn secondary, with a 4x15 toroid and
I'm getting many streamers and power arcs of 28 inches.  I think I could go
to a bigger toroid but only have one more turn available without adding more
copper.  Besides, if I make longer arcs, I will have to move out of the
house :-))

You may need to be within 1/2 to 1 turn to get good streamers

 > >From: JOSEPH CACCIATORE <jocatch-at-us.ibm-dot-com> (by way of Terry Fritz
 > ><teslalist-at-twfpowerelectronics-dot-com>)
 > >Subject: Tuning Questions
 > >
 > >
 > ><<<<<<<<<<<<<<<Third attempt to get this posted>>>>>>>>>>>>>
 > >
 > >
 > >I am now in the process of tuning my new coil. Short videos and pictures
 > >at my site, http://www.joecool-dot-org/joes_tesla_coil.htm.
 > >
 > >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. Instead of adding another turn or two why
 > >can't I just reduce the size of the toroid (the major diameter that is,
 > >still using 4" duct)? Using heating duct, it is very easy to do. Are
there
 > >any adverse affects reducing its size?
 > >
 > >I also noticed that grounding the case of the NST and the bottom of the
 > >secondary to earth ground didn't make much difference in spark. Adjusting
 > >the spark gap doesn't seem to make much difference either unless I go too
 > >wide or too narrow although I didn't make any actual measurements for
 > >either test. Adding a sharp point to the toroid, like a piece of wire,
 > >gives me about 18" sparks. Without the wire I get small break outs all
 > >around the toroid. I don't know with a 12,000v,
 > >30ma NST how much bigger I should expect. I will be playing around with
 > >the # of primary turns to see. Is there any way to ball park measure the
 > >differences during tuning other than visual?
 > >
 > >JC
 >
 >