10X probe Bode plots.

[dave slagle]

I have been trying to buy new sets of probes and keep running into an odd problem when I look at the 10X settings.  This seems inline with the issue that people have reported with trying to calibrate the probe to a square wave but my issue is a dropping response above 100Hz in the bode plots.

Here is the best square wave I can get 

 

which translates to this bode plot.

 

 

when I adjust the trim capacitor this is the worst I get.

 

 

This tells me there is clearly a range of adjustment it just happens to be outside the needed range .  I have probes that I can get flat but the majority of the probes I can get dialed in are older lower bandwidth ones.  I have everything from 20MHz  to 200MHz and there doesn't seem to be a specific pattern.  At best I can just get a probe flat and never seem to get an rise / overshoot and figure there has to be an obvious solution I am overlooking.  I have tried with and without the BNC adapter and it makes no difference.

 

any thoughts?

[JColvin]

Hi @dave slagle,

Regarding the BNC probes not correctly compensating, Digilent is actively looking into this.

At some point, the quality of the P6100 probes that we were procuring changed so that newer sets of probes are no longer to able to fully compensate the analog input signals as compared to the older batch of probes from the same manufacturer that were able to easily overcompensate the same signals. For our part, we are working on sourcing some new probes that will work consistently (the first new options we sourced did not perform as advertised in their datasheet) as well as seeing if any hardware changes can be made to the BNC Adapter for more reliable operation.

Unfortunately, what this means is that Digilent does not have solution to offer at this point in time, though we are actively working on it and as soon as I hear that a solution has been found I will let you know.

Thanks,
JColvin