From: Paul
Date: Wed, 13 Jun 2001 22:56:14 +0100
Subject: Re: [TSSP] Progress at 12/05/01
Hi Malcolm, The problem with the E-field pickup is that it collects some kind of average reading from the whole coil, which doesn't deliver a top voltage unless we calibrate the E-field pickup against a top volts reading from a directly applied scope probe at small signal. The trouble is, the calibration thus achieved, if applied to power operation, misses the very thing we are trying to home in on - the non-linear behaviour. So I'm hoping we can find a more direct method. Having thought about your 17" resonator, I doubt that it would be suitable. When the measurements disagree with the model, (as they probably will) we would not be able to rule out the possibility that the distortion of the coil former is responsible. I have the same problem with my h/d=1.36 - the coils are slightly barrel shaped - I've been using an average radius, which we get away with at f1, but it leaves doubt about where we stand at the higher modes. Really I'm trying to find some h/d < 1.5 coils that can be compared with the model on the basis of the geometry alone. Which means a coil with a minimal former yet maintaining good shape! Anyway, the 17" by 3.5' coil that you describe sounds ideal for some Q factor and eddy coupling measurements that I can think of, so it would be a pity to break it for that reason alone. Related to the Cint issue - does anyone fancy building a small h/d coil with around a dozen or so tapping points in order to measure a current profile? Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.