From: "Terrell W. Fritz"
Date: Sat, 17 Feb 2001 15:11:07 -0700
Subject: Re: [TSSP] Reactive part of base input impedance
Hi Paul, For the bare small-coil no top-probe I get: Q = 170.03 f1 = 358.81 V = 0.47218 (corrected scope) I = 2.6234 mA f45low = 357.87 V = 0.48419 (corrected scope) I = 1.9908 mA f45high = 359.89 V = 0.48419 (corrected scope) I = 1.8823 mA At 06:15 PM 2/17/2001 +0000, you wrote: >Hi All, > >If the base input impedance is described, in the vicinity of >f1, by > > Zin = Rin + jXin > >where > > Xin(w) = j(wLin - 1/wCin) > = jwLin( 1 - (w'/w)^2) > >and w' is 2 * pi * f1, we might be forgiven for assuming that >the equivalent input reactances are given by > > Lin = Les > Cin = Ces > >However the model flatly insists that the correct values are > > Lin = Lee > Cin = Les * Ces/Lee > >so that > > Zin(w) = Rin + j(wLee - Lee/wLesCes) > = Rin + jwLee( 1 - (w'/w)^2) > >I've been trying to account algebraically for Lee appearing >in here - perhaps I'm missing some obvious fundamental relationship >between the energy storage ability of a resonator and the slope >of it's reactance near resonance. Any suggestions? > >Perhaps a measurement would settle the matter? Terry, I think >you're the only one with a signal generator precise enough to >do this test. This would involve simultaneously probing >base volts and base current. Note the frequency at which the >two are exactly in phase, call that f1, and then find the >frequencies either side at which the phase difference is >+/- 45 degrees. From this, together with a Q measurement, we can >work out the effective value of Lin and see whether it equals >Les or Lee. Best done on the un-probed bare small coil, as the >difference between Lee and Les is the greatest. > >I've been reconfiguring the model to look at output impedance, >with the eventual goal, in the next installment of 'theory notes', >of being able to write down a thorough lumped equivalent circuit >for the secondary. > >Cheers, >-- >Paul Nicholson, >Manchester, UK. >--
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.