Rohde & Schwarz RT-ZC20B

[silv3rstr3]

I am attempting to calibrate one of these newer R&S RT-ZC20B (0.1V/A) current probes.  The calibration data that came with it shows the amplitude accuracy all in voltage.  They listed a 3458A as a standard.  This probe has a unique interface that I can't connect to a DMM.  The second you plug the probe into the R&S oscilloscope it automatically changes all the measure functions to current.  I even tried to use the math function to try and re-scale it with no luck.  I'm thinking there is some sort of probe amplifier box like Tektronix has for theirs.  Not sure but I really don't want to have to ship this to Germany when I have the right standards here.  Any suggestions?

[Bryan]

The probe delivers a voltage output proportional to the current thru the jaws.  That voltage needs to run in to a 50 ohm impedance meter for accurate measurement.  Shove the female side of a 50 ohm feed thru in there and connect the male end to an adapter for your DMM.  It should deliver 0.1V per amp applied thru the jaws.  That's my guess.

[silv3rstr3]

I definitely tried that first but it's not a regular BNC connector.  Feed through termination won't fit and the manual says not to hook it up to a regular BNC connector.  I know how to calibrate these.  The interface is something I've never seen and nothing like older current probes made by other manufacturers. 

[Hawaii596]

A couple of ideas come to mind... R&S, although they don't have everything on the website, are pretty good at supplying their service manuals that include their calibration procedures, when queried by email.  And in them, I would think, should be the various hookups.

Other than that, if there is not an available procedure that you can convert to what instruments you have, my initial thought would be to characterize the oscilloscope. Not sure how they did it with a 3458A. But We (for example) have the interface fixture for Tek P7xxx series, and a LeCroy fixture for (can't remember model #'s) some of their probes. In them, there is, as I recall, a tap to read a signal level directly. Perhaps that is the case for this R&S probe. Maybe they are using such a fixture, inputting x Amps or milliamps, and reading an output voltage value from a tap on a fixture.

[silv3rstr3]

I'm convinced there is a fixture of some sort for this.  When I wrote this yesterday I was also thinking about a couple weeks ago when I was talking with a Lecroy engineer about a 20kV high voltage probe.  We had to end up sending that one to Germany because there were no published specifications and they actually tested voltage, rise & fall time, and bandwidth all the way up to 20kV.  Had a brain fart and thought they were the same company.  Seems to blur together some times when you work on a wide variety of equipment all the time.  I'll e-mail R&S support and request the service manual.  The user manual is worthless.