From: "Terrell W. Fritz"
Date: Tue, 10 Jul 2001 19:35:17 -0600
Subject: Re: [TSSP] Toroid breakdown voltage indirect meas.
Hi Marco, At 02:18 PM 7/10/2001 +0300, you wrote: > >Tonight or tomorrow I'll measure secondary base current and (indirectly) >voltage. Current with a Pearson current probe (model 110A, calibrated a >few months ago, reads "High bandwidth", 0.1V/A) and voltage with the >"flying" scope probe. > >The Pearson current probe has got a N coax connector, but I use a >N-to-BNC adapter and a length of about 4 m shielded cable (I guess is a >50 ohm one). The probe should have a 3 dB attenuation @ 20 MHz, if I get >it right from >http://www.pearsonelectronics.com/Pages/Standard_Currrent_Monitors.html. > >Questions from you RF measuremnt guys: > >- should I set my scope input impedance to 50 ohms (to have a correct >termination) and then multiply my reading by 2? > >Best Regards > I would terminate into 50 ohms if you are looking at anything over 1MHz or need accurate phase information. "I" would also use an external termination instead of the built in one since they tend to get burn out ;-) Also, the termination provided a little protection to the scope input if anything goes wrong. However, below 1MHz, the termination is not really useful. I have two Pearson current monitors and they do all they say they will easily. Amazing little things!! Cheers, Terry
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.