What wrong is it, about my way to measure the secondary resonance frequency?

[VNTC]

What wrong is it, about my way to measure the secondary resonance frequency?
I have used this way to measure the secondary resonance frequency and I think it is a comfortable way. I have done verify by Pspice simulator and it shows this way is reliable that can give correct result.
Figure1 schematic the circuit to simulate by Pspice
Figure2 shows the AC sweep simulating to see the resonance frequency of L2C2 this is compatible with the formula F=1/2π√LC
Figure3 the 3 secondary coils
Figure4 the wave run by the third coil (highest coil run at 4.4 µs 227kHz) this figure is the clearest one the 2 other rather hard to observe because the signal is weak.
To practice this way, first lower the bus voltage about 30%-4
0%max (for more safety).
Then take a wire jump across C1 to get the tesla coil run in SRSSTC mode and let it self-oscillation (feed-back by antenna recommence).
This table below shows the resonance frequency of 3 coils L2 without toroid
I have verify these result by JavaTC and see some different. I don’t know why?
         Coil_1         Coil_2           Coil_3        Java TC    Measure    % accuracy
Number of turns   920    1840   1050         
Length of winding   6.63”  13.82”   9.7”   277kHz   232kHz   119%
AWG                            34      34      31           459kHz   363kHz   126%
Radius                    1.77” 1.77” 1.77”   493kHz   370kHz   133%

[Mads Barnkob]

Could you please format your "table" of data so its more what numbers are for what. It seems you have 3 coil data vertical, but measurements horizontal?

I tried 920 turns, 1.77" radius and 6.63" long of awg34 and got 425 kHz in JavaTC, so im wondering how you wrote that table

[Teravolt]

if it were me I would get a signal generator, it could be a 555 ic or a function generator, put a loop of wire at the base with a 50 ohm resister in series and sweep it. take the oscope probe and lay it on top or dangle it near the coil. add your torid teminal and watch the changing peak amplitude change  frequency. if you want to know Q mesure f1 and f2, .707 v peak , and calculate