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Tek Current probe TCP312 and TCPA300 amplifier

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Omicron:
Some time ago I was able to obtain a second hand Tektronix TCP312 DC current probe and TCPA300 amplifier. I was experimenting with these to see if they are still in a working condition. I observed the following:



This is a 40Hz square wave signal of 100mA amplitude. As you can see there is a peak at the leading and falling edges. This peak is not present in the actual signal but is an artifact of the current probe or the amplifier. I know these types of probes use a hall sensor for the LF part and a more conventional current transformer for the HF part. It seems almost like the HF and LF responses aren't matched. But there don't seem to be any adjustments inside or outside.

Has anyone seen this kind of thing before? Would this indicate a bad amplifier or a bad probe? Neither the probe nor the amplifier offers any adjustments apart from some basic gain adjustments as far as I can see.

Another thing I noticed is that the gain adjust on the probe doesn't seem to have enough range to properly correct a DC current measurement. It always reads a little low (about 5% and this probe in theory should be accurate to typically
1%, worst case 3%).

Any thoughts or ideas are most welcome.

free_electron:
is the clamp all the way closed ? (  there should be an led that tells you when it is. )

it almost looks like the degauss circuitry is still running..

Omicron:
Yes, all the way closed. There is indeed an LED on the amplifier that lights when you forget to close it all the way. When I press the degauss button it seems to do it's thing.

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