Series Resonance and Analysis of Filter 


I isolated the first stage of the High Pass filter to produce a simple resonant circuit. Note that resonance occurs at 877 kHz.  In the animation at bottom of we see resonance at about 700 kHz, and the Q of the resonance is much lower.  The changes in frequency is due to the effect of the second stage on the first stage of the filter. 




Notes: (1) L1 = L2 = 6.2 uH  [6.2 micro-Henries] .



In animation below, voltage readings indicate resonance at 700 kHz.  The L1/C1 high Q resonant circuit has been effected by the next stage.  This shifts resonance from 877 kHz to 700 kHz, and the Q of circuit has been reduced by damping effect of next stage of the filter. Lower Q is indicated by shallow dip of voltage at TP1 with respect to sharp dip in above animation.



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