Differential probes

*almost* differential. You can surely count on unmatched input impedance. It'll probably work ok on a low impedance circuit, but try to measure a diff voltage in a 10K impedance circuit. You might have some surprise.

I recently learned that the 7K plug-ins (only the vertical ones) work in my DSA601 scope. Just cut the polarizing finger and voilà, the only "inconvenience" being that there's no dialog between the mainframe and the plug-in, so you have to manually inform the mainframe. So I bought 2 7A22, and having them along with another 4 inputs plug-in in a

8 traces DSO is a _very_ valuable debugging tool.

Try this:

2x10 k matched ___ 100 kHz sine wave >-+-|___|----> IN1 | | ___ `-|___|----> IN2

The asymetrical impedances of a floating single ended probe will do wonders :-)

Of course, if in your case the 180V offset is DC or,only LF, then, no pb.

--
Thanks,
Fred.