Re: TESLA COIL REVISED

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

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

 >
 > I also need to interject here too.  A resonant frequency of 3.5 MHz is
 > hardy a frequency that most solid state tesla coil builders can consider
in
 > their design.  To date I am only aware of one person, Dan McCauley, who
has
 > successfully built a solid state coil with an Fres in the megahertz range
 > with any substantial (>100 W) input power without almost instantly
 > destroying the power circuitry.  Most of us don't have the skillz (yes,
 > with a z) necessary to pull this feat off.  Now this operating frequency
is
 > not out of the question with tube coils, but dealing with power supply
 > design becomes much more difficult as frequency increases when any stray
 > loop or conductive object close to the circuit causes changes in
operation.
 >

I should think that one could take the Class E/F 7 MHz kilowatt amplifier
designs from Rutledge (at Cal Tech), published in the ham literature and
build a CW coil.  It would be a MOPA (master oscillator, power amplifier)
rather than a power oscillator.  Runs off 100V DC or so power supply.

Uses a very inexpensive transistor.

I suspect that as you get up into the higher frequencies that the usual
approach of scaling up a switching power supply type circuit might not be
the optimum.  You probably want to go to a more classical RF amplifier.

All the articles describing the amplifier (and, I think, kits of parts) are
available at the CalTech web site.  google for Rutledge and Class F and
amplifier