[AMPS] basic question about dipping the plate

[Michael Tope]

> >
> >Rich has his own definition of "resonant".
> >
> ?  When XL = XC, a series or a parallel circuit is resonant.  For series 
> circuits at resonance, R is virtually zero.  For parallel circuits, R is 
> virtually infinite at resonance.  
> 

Yes, agreed. But the loaded L-network is neither a true series nor true 
parallel network. The impedance ratio of the resonant L network (Xc=Xl)
will not be infinite because there is a resistive load across the shunt
element. In this case, the currents through two reactive elements can't be 
equal and the resulting voltages drops will not be in antiphase as in
the classic series resonant tank. 

Just to give you the benefit of the doubt, I plugged some real numbers 
into my circuit simulator (Ansoft Serenade SV). With 10uH series L and 100pF 
shunt C and a 2000 ohm termination across the shunt C, I get an input impedance 
of 50 + j 8 ohms at the resonant frequency (5.03 MHz). At this frequency 
Xl = 316 and Xc = 316 ohms. This is hardly a dead short. Of course, when I 
place an open circuit across the shunt C, the network becomes a classic 
series tank and the input impedance at 5.03 MHz drops to 0 ohms. 

73 de Mike, W4EF..................................



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