Fred_Bartoli wrote:

Joerg a écrit :

Fred_Bartoli wrote:


[...]


How much is the scope probe capacitance consuming ?:-)


Hey, this is a brand new 200MHz scope that came with four spanking
new high speed probes :-D


Joerg,
you probably already checked it but just in case...
I've bought some of the cheap chinease 1/1:10 scope probe for slow
1:1 probing. That's perfectly OK for that. Now, to once do a quick
circuit check I flipped it to the 1:10 mode and scratched my head for
the bad results of my circuit for maybe an hour...
... until I noticed that the 1:10 attenuation was of by more than 20%.
Not AC response, but DC. What a crap!

Now I believe it's fortunate they got the 1:1 ratio right :-)


When the scope came that's one of the first things I checked. Took the
fast pulse generator. To my amazement they had even adjusted the
compensation very close to perfect.


Yep, pulse shape was OK too (for the price). But who would think of
testing DC attenutation? Now I do...


Hmm, should be almost an automatic habit. The manual of this scope
actually said so right in front and this was repeated on the cal sheet
in each probe pouch: Hook up probes to calibration point, adjust slope
and verify Vpp for both x1 and x10 settings. With a wrong DC level Vpp
would have to be wrong as well. And this is a Taiwanese scope, not from
one of the usual manufacturers. I bought it mostly because I absolutely
did not want to be stuck with the paltry 2.5K memory that Tektronix
offered. Now I've got ten times that.

--
Regards, Joerg

http://www.analogconsultants.com