From: Paul
Date: Sun, 19 May 2002 09:02:33 +0100
Subject: Re: [TSSP] Racing arcs
"Barton B. Anderson" wrote: > Paul, I rescoped the coupled modes.. These came up right away: > > Calc: Meas: > 59.9 59.1 > 72.4 71.4 > 235.4 237 > 367.1 356 Thanks, that's more like it. We're still about 1.5% out on the two beat modes and 3% out on the 5/4 wave secondary mode. We should be able to get better than 1% on them all, but I'll settle for 1% at the beat frequencies. Your mapping of the primary inductance as a function of tap position should help with that. If you take N readings we can gain a factor sqrt(N) on the accuracy. I'd like to concentrate on setting up the 'cmod' page to reflect the settings of the coils when tuned as you would normally do for longest streamers. If at the same time we can measure the mode spectrum, as you have done, on the other coils, we can then be sure that the apparent offset tunings are genuine. Once the cmod page has got the in-tune conditions thoroughly documented, we then have six degrees of freedom to move on each coil: tune up, tune down, primary up, primary down, toroid up, toroid down. I propose we set up a similar page to cmod, but for each coil demonstrating an adjustment in each of the six dimensions. Thus the cmod page will show the 'baseline' and we would aim for eg a page ba0 with each of the 6 adjustments documented. Ditto for jftt42a, jftt42b, etc. Alternatively, instead of an extra page for each coil, we could instead have an extra page for each adjustment dimension, ie a page showing the results for the 5 coils when tuned up, another for the 5 tuned down, and so on. Either way, we end up with a framework on which we can hang quite a lot of results without loosing track of where we are. The 'cmod' page of ideally tuned coils sort of acts as a hub, an origin if you like. This does mean that those taking part will need to be able to measure that mode spectrum and the coil inductances - will that be possible? Without that cross check I cannot be sure of the model's correct representation of the coils unless the coil is set up outdoors above a well defined ground plane. Indoors we could be 5% out or more if the effects of walls and ceilings are misjudged. -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.