Need Oscilloscope Probe Suggestions

[Hootis Tigglebits]

I use a Rohde & Schwarz RTB2004 oscilloscope daily at work, but I've found the included 10:1 probes (RT-ZP05S) lacking in quality. The tips are too large for my applications, and I would prefer slightly better accuracy when measuring signals in the 10 ns range or lower. I'm looking for replacement probes that meet or exceed the following specifications:

• Bandwidth: 300 MHz
  Max Voltage: 55V RMS CAT II
  Attenuation Factor: 1:1
  Input Impedance: 1 MΩ // 39 pF

The ideal probes would have a fine needle tip and a ground clip smaller than the standard alligator style. Can you recommend any probes known for their accuracy and durability that cost under $250 each? While I like the design of PCBite’s probes, their price makes me wonder if they are more suitable for hobbyists. I’m aware that TEK probes are highly regarded, but their cost may be too high for my boss to approve purchasing four of them.

[KungFuJosh]

I generally love the quality of ProbeMaster.com probes, but they don't make those specs unless 300MHz is a typo. I've not seen any 1:1 probes that do higher bandwidth. 30MHz is around the limits I've seen, though I haven't looked that hard.

[tggzzz]

What is "inaccurate" about your existing probes? Having a sharper tip probably won't improve accuracy.

At such frequencies there are many ways in which probes can be misused. For example, what is the load they have on the circuit? (Hint: not 10Mohm!) Will that affect your circuit?

Significant improvements in accuracy might require improved probing technique and/or a different class of probe. FRI see the references at https://entertaininghacks.wordpress.com/scope-probe-reference-material/

[Hootis Tigglebits]

Sorry for not being more clear, I've noticed when comparing the waveforms that these probes see vs. a Tek probe on the same scope that these tend to have more noise. The finer tip is needed due to the size components I work with, 1.3mm in diameter on the H&S probes vs .75mm in diameter on the Tek probe I have.  I'll read the link, but I was trained on using scopes by two seasoned electronics engineers, so I'm confident I'm using them correctly; however anything is possible.

[David Hess]

The Probemaster 4900 Oscilloscope Probe Deluxe Kit appears to have exactly what you are asking for, but 300 MHz means a x10 probe.

[Phil1977]

Regarding 1x probes:

[tggzzz]

Sorry for not being more clear, I've noticed when comparing the waveforms that these probes see vs. a Tek probe on the same scope that these tend to have more noise. The finer tip is needed due to the size components I work with, 1.3mm in diameter on the H&S probes vs .75mm in diameter on the Tek probe I have.  I'll read the link, but I was trained on using scopes by two seasoned electronics engineers, so I'm confident I'm using them correctly; however anything is possible.

Many seasoned electronics engineers use scope probes "suboptimally". It isn't a subject explicitly taught during courses, so many end up learning the hard way.

I would expect the trace from a *1 40pF scope probe to look less "noisy" than that from a *10 10pF probe, due to attenuation and the low pass filtering effect.

What was the signal amplitude, frequency, risetime for digital circuits, impedance and/or logic family?
Was the noise broadband or single frequency?
Was the noise correlated with the signal?

How was the probe connected to the UUT?

A photo of the problematic scope traces and how the probe is connected to the UUT would be useful.

[Fungus]

• Bandwidth: 300 MHz
  Max Voltage: 55V RMS CAT II
  Attenuation Factor: 1:1
  Input Impedance: 1 MΩ // 39 pF

300Mhz 1:1 ain't happening.

[BillyO]

300Mhz 1:1 ain't happening.

All depends on the depths of your pockets.  The "under $250" part is what's not happening for a 1:1 probe.

However, Tek P6139A probes can be had used in 9.5/10 condition for under $250.  They are 10:1 probes but I don't see that as an issue.  I don't know why the OP thinks it is.  However, they tick all the other boxes.  They are thin, miniature probes with a variety of ground options.  As well the user can modify the "normal" grond clip if they wish.