Re: Tuning help

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

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

Hi John,

Two comments:

Your  following statement suggest to me that you might have put some
instrumentation  on  the secondary output and if so, you would have deturned
the secondary.  I suggest that you repeat the secondary resonate frequency
measurement by connecting the signal generator to the base of the secondary
and measure the field created with a scope connected to a foot or two of
wire used as an antenna and positioned about a meter away from the
secondary.  Connect nothing except your top load to the top of the secondary
coil.  You can vary the source frequency to maximize the field the scope
picks up.  You can then measure the frequency of the source and that will be
close to your secondary resonance.  Next, I would measure the resonance of
the primary coil with your .05 uf capacitance connected in parallel.  Feed
the tank with your signal source thru a 10K resister connected to one side
of the tank and signal source ground to the other side.   Connect your scope
probe directly to the tank and scope probe ground to the other side of the
tank (same place where your signal ground connection is made).  Vary the
signal source frequency until the tank response peaks out as measured with
the scope.  The freqency of the source is the resonant frequency of the
tank.  You can then vary the tap until the resonance frequency matches your
secondary.  This will get your tuning close and you can then fine tune it in
real operation.

I don't have any MOT experience so you may want to recheck if .05 uf is too
big for your power source.  With  15KV 120ma NST the LTR capacitance is .056
uf.  I'm thinking with this value your primary resonance may be much lower
than you think it is.  Best to check it with a scope.

Hope this helps

Gerry R
Ft. Collins

 > Misc
 > When feed from my oscillator at 363kHz and 10 volts
 > a voltage of about 400 volts is generated

 > John
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