From: Paul
Date: Fri, 29 Dec 2000 23:28:02 +0000
Subject: Re: [TSSP] coil measurements
Metlicka Marc wrote: > i tried to take some L measurements, but i'm not real secure in the > correct nature of these readings. i don't have a manual for the 250 de > yet but i'm working on it. OK, understand you've now got a manual on the way. > ... and i'll keep trying for an L reading. Yes, we'll need some accurate inductance readings for all the coils. Ideally two readings for each coil - one with the coil in its test position above the ground plane, and another with the coil well away from anything. > the #4 coil was given to me last night so use it if you want to, the > 10-1 is still set up in it's test position, if you want to concentrate > on one at a time i'll setup whichever and duplicate the readings, then > we can go from there. I don't mind whether we look at one coil or all three. Are you saying that #4 is available long term for tests? Check that the screen of your base feed coax is connected to the ground plane, and that it is the only connection between groundplane and the building earth. (Otherwise, a big loop is formed, only 1 turn but a large area for eddy coupling). You gave me for coil #2, peaks at 227.4kHz and 712.3 kHz. There should be one in between at around 556 kHz. Can you check the 712.3 kHz reading, it would be better if it was at 812.3? If so then the missing peak will be at 579 kHz. There's something odd about coil #1, you gave me 455.53 kHz and the simulator predicts 382.9kHz, thats -16%. That's well outside the expected prediction error. Have you any idea how many turns it has? I'm using 1380 to match the resistance, You sent me, for coil #1, |1: bare coil form dia. 3.514" (9-1 dh) | 31.804" wound length | .020" wire dia., 24g, .0257 ohms per ft. | resistance of windings: 35.8 ohm ( with fluke 87III), | 34.4 ohm ( with ESI lcr bridge) | first res. V peak: 455.53 khz | ground to first winding: 13" Can you check that everything is OK there? Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.