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## Re: [Amps] R. MEASURES PRAYERS ANSWERED

 To: g3rzp@g3rzp.wanadoo.co.uk Re: [Amps] R. MEASURES PRAYERS ANSWERED R L Measures Sun, 4 Jun 2006 05:23:52 -0700
 ```On Jun 4, 2006, at 1:26 AM, 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. In a parallel-resonant tank, true, in a (low-pass) Pi-network, the E- I relationship between C1 and L are not quite in phase, and the sane thing is true for L and C2, however the current and the voltage at the output are in phase, so all's well that ends well. As I see it, an L network is a cross between a transformer and a tuned circuit. > 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. > > Operating into a non-resonant load leads to an elliptical load line > - see Pappenfus et al. My dummy load is non-resonant, so that's a problem? > 73 > > Peter G3RZP > > R L MEASURES, AG6K. 805-386-3734 r@somis.org _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps ```