I have reduced my primary to 5 turns, and using the standard 0.068 MFD tank cap, this is the general shape of my oneTesla output waveform (as captured by a scope probe hanging in the air about 3 feet away from the coil):
As you can see, the primary rings up and then the secondary oscillates for quite a while afterwards.
The next three traces are running the coil at a very low power level. Depending upon where I measure between peaks on the trace, I get different frequencies:
17.80 uS between five peaks, or 1 / (3.56 / 1000000) = 280 kHz
As the 280 is between the 277 and the 294, we’ll just say that my primary has a resonant frequency of 280 kHz, when at low power.
Next, I turned the power up a bit (around 1/3 of the way up) and got the following two measurements:
18.40 uS for 5 peaks, or 1 / (3.68 / 1000000) = 272 kHz
So my primary resonance is somewhere between 263 and 294 depending upon how I measure it, with a value of 272-280 looking to be a reasonable average.
Surprisingly, my secondary resonance measurements agreed with themselves a bit better. Here is the low power trace:
And the “Mid Power” trace.
(You can see the primary ringing extending out so that it becomes visible in the trace…)
In both cases, I measured 15.20 uS between 5 peaks or
1 / (3.04 / 1000000) = 329 kHz
So my ratio is currently 329 / 280 or 1.175 ( Secondary 17-18% higher than my primary).