Re: 4.5 inch coil upgrade

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

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

Hi, Steve,

Since you are using a static gap your PF should be around .5 (assuming that
your gaps are set to not overvolt.  JF formula (1.7 sqrt (0.5 * 12K * 0.06))
yields 32 inches so you are doing good.  You could increase k somewhat by
adding those two inner turns, but I would still keep the coil flat.  You can
increase k by raising the primary relative to the secondary but not so high
that you get racing arcs or attract sec to pri strikes.  Doing so could
lower your gap losses somewhat.  The biggest way to increase power to the
secondary with your setup is to go to a SRSG.  This will allow you to charge
a larger Cp and get more energy per bang.

Gerry R

 > Original poster: "steve" <steve_vance-at-cablelynx-dot-com>
 >
 > Hi List, I just got done upgrading my 4.5" coil. I changed the transformer
 > from a 12-30 nst to a 12-60 nst. Added a strike rail, and changed my caps
 > from homemade to a mmc. I am getting streamers about 38" long now. I think
I
 > should get more though. I think the problem is the coupling. The secondary
 > is 4.5" and the primary hole is 8" According to javatc the coupling is .1
k.
 > My question is: If  I add two more turns to the inner part of the primary
 > and raise the outside 14 deg. to make it an inverse conical, the coupling
 > should increase to .146 k. Will this increase the streamer length enough
to
 > justify the modification? Is 3/4" enough clearance between the primary and
 > secondary?
 >
 > You can see the coil here.
 > http://fire.prohosting-dot-com/~bonestc/4.5inchcoil.html  The photo at the
 > bottom of the page is with the new setup.
 >
 > Steve Vance
 >
 >