From: Paul
Date: Sat, 18 May 2002 14:19:36 +0100
Subject: Re: [TSSP] Experiment 7
Terry wrote: > So I too am in the "pondering" stage... Yes. One thing's for sure, substantial variations in Q really do occur, and this reduces the importance of working out things like proximity loss to umpteen decimal places. It means for example that CW drivers must be constructed to cope with quite a range of loads no matter how carefully the coil's impedance is calculated in advance. Therefore I think that ponderings ought to be going in the direction of identifying the sources of loss, not so much quantitatively, but more with a view to finding practical ways to minimise the total losses of a CW system, since there we obtain some direct and immediate performance benefits. For example, I built my CW coil large, with thick wire and modest h/d in the hope of getting a really good Q factor. The DC resistance is 7 ohms and maybe 30 or 40 ohms at the operating frequency. The Q should be over 1000 but I get values usually from around 100 to 250. Somewhere in there is room for up to a factor four improvement in performance and it would be nice to be able to refer to a body of work which described the various mechanisms by which the coil leaks energy into its surroundings. We shouldn't attempt to find ways to predict the size of these losses - merely demonstrating their mechanism and estimating the proportion of their contribution to the total loss would be of most use, I think. So perhaps that's the way we should go. -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.