Author Topic: Agilent N2890A Oscilloscope Probe compensation  (Read 197 times)

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Online eb4eqa

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Agilent N2890A Oscilloscope Probe compensation
« on: January 06, 2020, 11:09:24 am »
Hi all and Happy New Year !

The instructions to adjust the probe compensation (https://manualzz.com/doc/9046234/n2862b-n2863b-n2889a-n2890a-passive-probes-data-sheet-cha...) show only two trimmers for the HF compensation, but the body with the BNC connector has three. If you dare to open the case, you find two more...

I understand there should be no reason to touch the ones inaccessible from outside, but the other three are probably behind a hole for a good reason. Now, the two on the sides have a clear effect, as explained in the instructions, but the one in the middle has no effect that I can find.

I haven't find much information about this three-trimmer probe on internet, but someone from Asia has been playing with them, even drew a schematic: http://www.360doc.com/content/17/1010/19/42387867_693844724.shtml

The information I found on the internet regarding probe compensation seems to be more basic than this scheme. It would be great to understand what all those trimmers are there for. Does anyone know?

Regards,
Roberto EB4EQA



 

Online David Hess

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Re: Agilent N2890A Oscilloscope Probe compensation
« Reply #1 on: January 06, 2020, 04:59:13 pm »
That looks like a probe OEMed by TEXAS.

The other compensation adjustments are for high frequencies.  If you did not see an effect when adjusting them, then it was because your signal source or oscilloscope was not fast enough.

Higher frequency high impedance inputs, like 250 MHz and higher, require high frequency compensation in the probe to compensate for non-ideal behavior of the high impedance input.  You might have noticed that Tektronix will release a new series of probes with the same bandwidth when they release a new oscilloscope series.  The reason for this is that the new probes have different high frequency compensation for the new oscilloscopes.
 

Online eb4eqa

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Re: Agilent N2890A Oscilloscope Probe compensation
« Reply #2 on: January 06, 2020, 06:32:26 pm »
Hi David,

You are right. A few minutes searching and I found this Agilent N2890A probes are exactly the same as the Texas TX6250. Even the accessories supplied are exactly the same ones. I hope to find more info regarding how to adjust that following that path.

Thanks!
Roberto EB4EQA
 


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