SSTC Twins

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

Original poster: "Steven Ward" <srward16-at-hotmail-dot-com> 

Hi All,

Ive been working intensly on some SSTC twins.  For a brief history, look at 
my site :

http://hot-streamer-dot-com/srward16/

http://hot-streamer-dot-com/srward16/SSTC4.htm

Ive basically come a very long way since i started this project.  I managed 
to kill 4 big mosfets from reasons unkown, but i suspect poor tuning with 
my free running oscillator.  Now im back to running small Mosfets, but lots 
of them!  Im using a dual H-bridge of IRFP260s.  At 120V input and just 
over 15A i get some nice 26" sparks between coils.  28" is my current best 
spark.  I also got an antenna driven feedback method to work very will with 
the twins.  This is the key to the long sparks, the coil is always in tune.

Now ive got a question about twin coils.  Can the secondary coils be out of 
tune?  Im running the bases together, but NOT grounded.  I figured, if 
there was any error in Fres between the coils, the lack of ground would 
compensate.  Can any one explain how twins (in my situation) work as far as 
Fres...  My feedback can only tune to one coil, so is my other driver 
simply always going to be slightly out of tune?

Another note, anyone going to the cheesehead teslathon this saturday can 
(hopefully!!!) look forward to seeing the twins doing maybe some 30" arcs.
Im etching the final PCB on tuesday and if it works like it should, the 
coil will be ready for action.  I cant make any promises though...

Any comments or questions are WANTED ;)

Steve Ward