Seeing that your coil has the same resistance as the replacement coil I received, and that your inductance is very likely the same as well, I would be very, very interested in seeing either an inductance value from your secondary or a measurement of the secondary resonance frequency. One way of doing it is as shown in a previous post in this thread, and another way that might give better results when using a low cost signal generator is described in my tuning guide, currently on page 4:
http://www.itn.liu.se/~stegu/onetesla/o ... _draft.pdfIf your signal generator is not happy with a shorted output, you might want to add a small resistor in series with the primary. (Note: in series, not in parallel.) 100 ohms should be enough. Commercial signal generators are designed to be robust against short circuits, so they should be fine, but if you build your own oscillator, it might need that resistor on its output to behave well and not risk taking damage to its output.
If your secondary coil is in fact similar to my replacement coil, it means that your secondary is tuned somewhere around 315 kHz, 25% higher than the primary frequency of nominally 250 kHz. It would be very interesting to learn that the strongest spark comes from a coil that is 25% out of tune at min power. This would mean that a "perfectly tuned" oneTesla (tuned for maximum spark length) is just on the verge of breaking from detuning at medium power, but when it hits full power it gets into tune. AFAIK, that strong of a shift in frequency in the presence of a streamer would be unheard of in coiling circles, but the oneTesla is an unusually strong DRSSTC for its size.
If you can find a capacitance meter, could you measure the tank capacitor as well? (Disconnect the primary from its terminals before doing this, or the rest of the circuit will disturb the measurement.) Capacitors tend to have a rather high tolerance, and yours might not have the nominal value. People's primary coils are bound to be very similar, so the tank capacitor is what determines the primary frequency the most.
An oscilloscope trace from a running coil at min power is also a very good way of measuring both the primary and the secondary resonance frequencies. See pages 2-3 in the tuning guide above. If you make this kind of measurement with an oscilloscope, all other measurements are in fact optional. Informative, but optional.
I am sorry to request all this work from you, but we are all very interested in getting more data on tuning for the oneTesla, and you would be doing a great service for the community.