Tuning your toroid

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

Original poster: "Skip Greiner by way of Terry Fritz <twftesla-at-uswest-dot-net>" <sgreiner-at-wwnet-dot-com>

Hi All
 
I usually tune my Tesla secondaries by varying the size of the toroid and
thereby adjust the Ctop capacitance. Its simple to do and works well. I use
various sizes of the flexible dryer duct that we all know so well.
 
First, you have to determine the minor diameter of the toroid which is usually
dependent on the breakout voltage.
 
Second, you must estimate the approximate major diameter of the toroid, either
by experience or from information gained on this list.
 
Obtain a section of the selected size duct.
 
Now, form the toroid to the approximate diameter and tape the ends together
with masking tape.Tape the partially complete toroid to a piece of insulating
base material such as stiff cardboard or thin masonite. This base should be
stiff enough to be balanced on the output insulator of the secondary. Now, add
a couple of small pieces of adhesive backed aluminum tape from the toroid to
the center hole and carefully bolt the toroid to the secondary.
 
Make your tuning measurements. If the resonant frequency is too high, merely
remove enough of the tape so that you can expand the toroid to increase the
capacitance. If the resonant frequency is too low, merely compress the size of
the toroid to lower its capacitance.
 
When you are satisfied, glue it all together permanently and you have a
perfectly matched system.
 
Skip Greiner