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MDO3000 hacking

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dmderev:
Did anyone confirm that TEK LA cables are lossy? There are two types of probes in TEK list - active probes have a bit thicker wires and are for sure just non-lossy gang coaxial cables, and there are also thinner passive probes. Are the latter lossy? Anyone measured parameters? Or any references to their design?

Howardlong:

--- Quote from: dmderev on June 04, 2024, 12:47:25 am ---Did anyone confirm that TEK LA cables are lossy? There are two types of probes in TEK list - active probes have a bit thicker wires and are for sure just non-lossy gang coaxial cables, and there are also thinner passive probes. Are the latter lossy? Anyone measured parameters? Or any references to their design?

--- End quote ---

Here you go https://www.eevblog.com/forum/testgear/mdo3000-hacking/msg765377/#msg765377

44kgk1lkf6u:

--- Quote from: Howardlong on September 27, 2015, 06:49:20 pm ---You might even get away with fabricating an entire probe, but that inline resistance is in there for a reason, there's a really old Tek document about it somewhere that I can't locate right now, but it's also covered here http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf.

--- End quote ---

There is a Circuit Concepts series.  Page 15 of volume Oscilloscope Probe Circuits talks about the lossy cable.


--- Quote from: Howardlong on September 27, 2015, 06:49:20 pm ---I don't know if the Agilent/Keysight probes have this distributed resistance too, they do have a fancy woven cable on the two examples I have so I wouldn't be surprised.

--- End quote ---

It looks like they also use lossy cables.  I searched on the web and found this in the 16557D logic analyzer card service manual.


--- Quote ---The probe tip networks comprise a series of resistors (250 Ohm) connected to a parallel combination of a 90 KΩ resistor and a 8.5 pF capacitor.  The parallel 90 KΩ and 8.5 pF capacitor along with the lossy cable and terminations form a divide-by-ten probe system.  The 250-Ohm tip resistor is used to buffer (or raise the impedance of) the 8.5 pF capacitor that is in series with the cable capacitance.

--- End quote ---

mgonee:
hello.
I tried to do this but without success.

python gen.py MDO3012 C024186 500MHz AERO AFG AUDIO AUTOMAX COMP DVM EMBD FLEX LMT MSO PWR SA USB VID AUTO SEC

Could you please help me.
Thank you very much.

Evan.Cornell:
I had to use python2 instead of python3 when doing this.

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