[Test-Equipment] Fluke current clamp probes & scopes

[Mike Manes]

The specs for that probe go down to DC, so most likely it's got a
Hall sensor or some such, along with signal conditioning electronics
powered by a replaceable battery.  It seems to be intended for utility
type loads, with a 600A FS range and sensitivity of just 1 mV/A.  Sounds 
expensive, too.

If you don't need DC response and no more than 60A ac FS, then a Harbor
Freight clamp-on meter would be a more economical solution.

73 de Mike W5VSI

J. Forster wrote:
> 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
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> 
> 
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-- 
Mike Manes    mrmanes at gmail.com     Tel: 303-979-4899
"Things should be made as simple as possible, but not more so."
A. Einstein