[Amps] R. MEASURES PRAYERS ANSWERED

[Steve Thompson]

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.

Steve