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pdavitt
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Posts: 9
Joined: Sun Mar 24, 2019 11:10 pm

I find that the probe leads out of the TA041 are too short for electrical enclosure use. Can I use my Fluke 4mm terminated, 1.5M cables as extensions, or will they skew the measurements? If they will skew the measurements, how can I compensate?

Thanks,
Pat

Gerry
PICO STAFF
Posts: 405
Joined: Mon Aug 11, 2014 11:14 am

Hi Pat,

They shouldn't skew the measurements as you typically shouldn't be measuring the highest frequencies that the Probe is capable of measuring (unless you're working on something like Plasma Power Generators, which they probably wouldn't be suitable for anyway).

Let's just do some quick calculations to show you what I mean. The speed of a signal (i.e. light) in a vacuum is 299,792,458m/s. The speed of a signal in a cable/lead is debatable, but will be between 50% to 99% of the speed of light. Typically, the time taken for a signal to pass through the fluke lead would be about 66% of 1.5/299,792,458 = 3.4ns. The maximum frequency measurable with the TA041 Probe is 25MHz, which is a Waveform period of 40ns. This means that at 25MHz the delay in the Fluke lead would be 3.4/40 = 0.085 of a waveform or 30.6 degrees (i.e. you get a 1.2 degree phase delay, for every MHz of signal frequency that you're measuring). To put this another way, for a 1MHz signal, you would have to be sampling at 300MS/s (with all noise removed) to even be able to see a 1 degree phase delay between your Fluke lead and a very short probe lead <minor changes made>.

However, you would need to ensure that the Fluke leads are suitably rated to measure the voltage that you using the Active Differential Probe for, i.e. if you needed a 700V CAT III Probe, then the Fluke leads should be similarly rated.

Regards,

Gerry
Gerry
Technical Specialist

pdavitt
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Posts: 9
Joined: Sun Mar 24, 2019 11:10 pm