> >
> >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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