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Re: [TCML] MMC and max voltage ratings

**Dr. Antonio Carlos M. de Queiroz posted the following scope method a while back:
Connect a 1 Ohm resistor across the output of the signal generator, to have a low-impedance signal.

Connect the signal generator where the spark gap would be, with a low-frequency (1-10 kHz) square wave of maximum amplitude. The secondary coil and top load should be in place. Ground can be at the oscilloscope ground.

Look at the voltage over the primary capacitor, or over the primary inductor, at the transitions of the square wave. Tune the system until you see full notches, like in this photo:

This is the ideal tuning without breakout. To account for streamer load, connect a wire to the top load with the length of a reasonable streamer and tune in the same way. Mark the two positions found. The best point will be somewhere between these. Note that the waveform shows also the resonance frequency of the two tanks, and allows the measurement of the coupling coefficient.

Or build a Terry Tesla Coil Tuner!

There are a lot of methods to tune a coil. One thing to think about is the "ideal" tune is not necessarily right at equal resonances. All my coils run better with a little added primary inductance. Many coils run a little detuned in the range of 3% to 8%, where the primary resonant frequency is slightly lower than the secondary resonant frequency (detuned a little high on primary inductance). This may be due to streamer loading or whatever. Once you get the coil where the tuning is good on the scope, don't discount a little trial and error to see how it does with a little detuning.

Take care,

Stephen J. Hobley wrote:
Actually 12 caps in series would probably be fine too...
Off topic: Has anyone tuned their coil with a signal gen/scope ? Steve
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