Oscilloscope probe loading

[Veketti]

Hi,

I'm tempted to purchase Probemaster spring loaded probe for my Siglent scope. The question I have is, do the probe have to have same 17 pf value than the scope inputs do? Original probes seem to be 18pF Or would the Probemaster PM4913-1 with 11 pf work just fine?

Thank you in advance

[TimFox]

Normal passive probes have a trimmer capacitor to get flat response with a given ‘scope input.
They are specified to work with a 1 megohm input resistance and a specified range of input capacitance.
The capacitance seen at the probe tip should be smaller than the ‘scope input capacitance.
What are the relevant specs of the probes and your ‘scope?

[Veketti]

This probe that I was looking at has 10M-ohm, 11pf, 10x attenuation and 300MHz. Scope inputs are 1M-ohm, 17pF and 200MHz BW.

[TimFox]

In the probe spec, what range of ‘scope input capacitance will it work with?
(The probe trimmer adds to that capacitance to give the “bottom end” of the probe divider.)

[2N3055]

Compensation Range is 10pF to 50pF for Probemaster PM4913-1.
Datasheet.

[Veketti]

So for dummies, did I understood right that as long as the probe compensation range is within the scope input capacitance range I'm good to go?

[2N3055]

So for dummies, did I understood right that as long as the probe compensation range is within the scope input capacitance range I'm good to go?

You didn't say which exact scope you have.
Input capacitance is normally written on front panel of the scope, near inputs.
You should be OK, but it might be fiddly because range is so large (10-50pf).
It would be better if it was 10-25pf, for instance, it would is easier to adjust trimmer when range is smaller..

[David Hess]

Hi,

I'm tempted to purchase Probemaster spring loaded probe for my Siglent scope. The question I have is, do the probe have to have same 17 pf value than the scope inputs do? Original probes seem to be 18pF Or would the Probemaster PM4913-1 with 11 pf work just fine?

The oscilloscope input capacitance and the probe tip capacitance are unrelated, so the Probemaster PM4913-1 will work fine.  The lower tip capacitance compared to your old probes will actually improve measurement accuracy.

What matters is that the compensation capacitance range of the probe must match the input capacitance of the oscilloscope.  For the Probemaster PM4913-1, the compensation range 10pF to 50pF so again, this will work fine with your oscilloscope.

[Veketti]

Thanks David, that's clear.

[Bill3745]

Hi,

I'm tempted to purchase Probemaster spring loaded probe for my Siglent scope. The question I have is, do the probe have to have same 17 pf value than the scope inputs do? Original probes seem to be 18pF Or would the Probemaster PM4913-1 with 11 pf work just fine?

Thank you in advance

Did you end up buying the PM4913-1 and if so are you happy with it?  I was looking to pick up one myself.