From: "Terrell W. Fritz"
Date: Sun, 04 Feb 2001 19:36:05 -0700
Subject: [TSSP] TeK P5100 probe
Hi, I just wanted to report that my new Tektronix P5100 probe (2500V 250MHz) works extremely well. Not a cheap probe ($250), but does its job perfectly. It has level and compensations adjustments but they were all perfect when it came. It is also a pretty nice tough all around probe too. What is really surprising is that it loads the top of my big coil very lightly. The frequency dropped from 148.05kHz to only 135.24kHz with the probe in place! That is only a 3.0pF load even though the cable and all is leading to the coil (it also has a very long cable which really helps!). I think it is the perfect probe for measuring top voltages. Maybe want to keep an eye out for them at hamfeasts and such. I also looked at the scope calibration and it is within spec. It only has an 8 bit flash D/A converter so a lot of its error is do to that. Not a good tool to make 0.01% measurements with but it is operating properly. I also continue to be totally delighted with the 33120. You never know what you are missing till you have one of these puppies. It is extremely accurate and the measurements are totally repeatable. It takes all the guess work out of TC measurements. You just decide what you want it to do and push the buttons... No more fiddling with knobs and such. I have noticed that many TC driving functions take only about 1 volt with a low Z drive. However, the currents are usually in the mA region so perhaps a simple op-amp is all that is needed to drive a coil at low impedance and low voltage. Such an option may be better than the isolation resistor drive and transformer drive since it is very simple. Need to think more on that. Voltage and current measurements could be incorporated invisibly with a few more op-amps. You could also rectify the signals and drive meter outputs so you could get very accurate measurements with only a DVM... Didn't do too many real measurements today since I was too busy just playing :-)) Cheers, Terry
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.