From: Paul
Date: Sat, 03 Feb 2001 06:53:29 +0000
Subject: Re: [TSSP] Top voltage testing
Terry, I've been going over the Zft measurements made with the 10 ohm shunt. Supplying the HP with a little extra voltage seems to make all the difference to its accuracy. You wrote: > Fo = 105087 Hz > Vin(HP) = 0.66586V > Iin(HP) = 1.1742mA > Vtop(Tek) = 53.1V > Zin = 567.08 ohms > Gain = 79.75 > Zft = 45.222K I'm not quite sure where we stand now with the Tek calibration wrt the HP, but we do seem to be in the right ballpark now with Zft. You've probably not adjusted the current to account for feedline capacitance, so I suspect the true value of Zft might be a little higher than the value above, so if anything the model is erring on the low side with Zft predictions. Hopefully some of the others on the list will be able to come up with Zft measurements too, so that we can try to establish the trend. I intend to have a go at this too as Zft is one of the few things that my limited equipment has a chance of measuring - but that won't be for some time. In this respect, does anyone know if/where in the UK I can purchase a machine wound secondary of small size? Quite where we are with voltage gain measurements I'm not sure now. Apologies for the late response to your results, and thanks again for your efforts with these time consuming but valuable measurements. I'm starting a new web page for the tssp site which will summarise gain, Q, and Zft comparisons, so readings from list members of any of these will be most welcome. Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.