Peter Chadwick wrote:
> Rich said:
>>1. Pi-networks are never operated at resonance, they are operated
> close to resonance. Low-pass Pi-networks resonate a bit lower than
> the operating freq and high-pass Pi-networks resonate above it.<
> If it isn't resonant i.e. volts and amps are in phase, then you won't get
> maximum output and will likely get worse IMD. I am aware that the US Extra
> Class licence exam defines resonance as XL = XC, but this is only an
> approximation, and falls apart very badly when the working Q is low. If you
> use the only definition of resonance which holds up under all conditions i.e.
> the input impedance of the network is resistive (as far as the tube sees it -
> strays will have some effect if you calculate and compare with reality,
> especially on the higher bands), then the pi network is resonant. So is the L
> network, but if you use XL = XC, then both cases suggest that the circuit
> isn't resonant.
Being pedantic, any definition of resonance has to apply to any and all
systems, not just a tuned circuit. Whatever applies to a spring, or air
column etc., has to be translated into appropriate electrical terms.
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