RF Current probes Episode 9 - A pair of matched probes

[@koelie17]

Nice video! Can you maybe do a video on the use and added value of using an RF absorbing clamb ? ( Like the mds 21)? Keep up the amazing work

[@MJ-vt1kp]

Hi, do you have experience that for low value CM current possision of the probe on the cable give diffrence results due to coupling E field to the probe/cable. What should be best position of CM current probe for HF RF measurments, low value let say above 500 MHz to 3 GHz. Is current probe as a metal structure influencing the results by making shunt capacitaince for CM current and as results we got less current? Regards

[@tomasbergh]

So am I right if I say that the part of the waveform that is present on both sides of the transformer is conducting through the stray capacitance between primary and secondary winding in the transformer?

[@MachOneDesignEMC]

Correct Tomas, but I failed to find a way of finding the rest of the CM current. You know, I thought the CM on the primary side and the secondary side should be more or less the same level, but, as shown in this video, the primary side of the current is a lot less. I suspect it is due to the CM filtering on the AC side. But how can we prove this without taking all the filters out? If our assumption is correct, then there must be another path returning the CM current back to its source, just before the filter. Difficult to measure in this case!

[@tomasbergh]

@@MachOneDesignEMC Hi again, if the CM-current was exactly the same on primary and secondary side, wouldn't that mean that there is no radiation at all from the primary side? The radiation that is common between the primary and secondary side consist of what the stray-capacitance is able to transfer. Ideally, without stray-capacitance, the radiation from the primary- and secondary side may look totally different I suppose?