[Test-Equipment] Fluke current clamp probes & scopes

[DaveC]

Once again the conclusion is that Dave has much to learn... :-)

Thanks John,
Dave

-=-=-=-

>There is NO requirement that the source impedance (20 Ohms) match the load
>impedance (1 MOhm) UNLESS you are dealing with RF where there is a need to
>"match" the impedances to reduce reflections.
>
>The Load Impedance spec of 1 MOhm is to maintain the calibration of the
>probe (V/mA).
>
>The probe, most likely, has a current transformer and a resistor across
>its secondary inside.
>
>The Fluke info is entirely reasonable.
>
>Best,
>-John

===================

>  > I've been looking at some Fluke current clamps for use with
>>  oscilloscopes. These output typically 1mV/1A and have a BNC
>>  connector. With a banana adapter it can be used with a DMM.
>>
>>  I looked at the specs for a couple of these clamps (i410, i200s) and
>>  was quite surprised to see that the output impedance is spec'd at <20
>>  ohms (not Kohms, or Mohms). The "load impedance" was spec'd at 1 Mohm.
>>
>>  See here for the i410 & i1010 PDF user guide:
>>
>>  <http://assets.fluke.com/manuals/i4101010iseng0200.pdf>
>>
>>  here for the i200 & i200s PDF user guide:
>>
>>  <http://assets.fluke.com/manuals/i200s___iseng0500.pdf>
>>
>>  I'm confused about how these mV output clamp probes can be used to
>>  obtain an accurate signal level on an oscilloscope if the output
>>  impedance is not 1 Mohn (the commonly-accepted norm input for scopes).
>>
>>  Fluke tech support was no help in determining if this was a misprint
>>  or to even understand how such a non-standard output impedance could
>>  impact measurement.
>>
>>  I could go on the premise that Fluke wouldn't be selling any of these
>>  "scope" type current probes if there was such an impedance mismatch,
>>  but I'd really like to understand if/how well such a combination
>>  works.
>>
>>  Is anyone using such a probe with a scope? Is the amplitude viewed
>>  correct? What model probe do you use?
>>
>>  Thanks,
>  > Dave