Smooth corona or heavy spark, RF wave radiation frequency of Tesla coil drops ve

[VNTC]

    In this very short  topic, I concentrate on only the matter “resonance frequency of Tesla coil is variable how many amount under spark situation”.
    After hit good tuning i observe the image of the RF radiation wave of my testing Tesla coil with the oscilloscope under a variable ‘power output’ (all parameters are constant, used antenna to get signals, in heavy spark take measurement at the end of burst duration corresponding with highest current in primary coil)
Burst duration   AC power in   Spark length   Period of output RF wave
        35us            50W         10cm                41us/6cycles
       140us          500W          55cm                42us/6cycles

    Image 1 6cycle in 41us scope the wave in 1st condition

    Image 2 6 cycle in 42us scope the wave in 2nd condition

    Oscilloscope were set up and observed in one time only adjust the duration of burst duration for 2 condition for eliminate mistake.
    I am not  surprise about this result because I have seen many time before. Now I need to see clearly again before share.
    By these information I cannot say different that “under fuul load resonance frequency of Tesla coil is drops very litle 2.5% approx..”.