Cheap Oscope Probe Quality

[alm]

Examining it more intensely, there is a 1mV reduction in the over shoot, and minor ringing in now flattened out.  The rise time is interestingly longer by 0.5ns on all probes compared to using the ground clip.  Very odd result, but the signal quality is improved, but not much.  Will post photos when able.

Over shoot will result in a faster (apparent) rise time, although I'm not sure if 1mV over shoot explains 0.5ns rise time difference. I would definitely trust these measurements over measurements with a long ground lead, those things shouldn't be let anywhere near high-speed signals (unless your scope has an extremely low input capacitance, like active or lo-Z probes). The usual way is with a probe-tip to BNC adapter, preferably with internal 50 ohm termination, otherwise with feed-through termination between it and the generator.

[saturation]

Sorry, my bad its not 1mV overshoot, its in the 360mV range, as pictured here.  The rise time estimate is about there, here its 0.7ns.


White = alligator ground clip

Yellow = spring clip

I just repeated some measurements with the spring clip on both the Sun and Rigol probes, all 4 of them, they ship 2 pair in a box.  I also checked the spring clip's effect on a Velleman probe, rated at 60 MHz.

Examining it more intensely, there is a 1mV reduction in the over shoot, and minor ringing in now flattened out.  The rise time is interestingly longer by 0.5ns on all probes compared to using the ground clip.  Very odd result, but the signal quality is improved, but not much.  Will post photos when able.

[saturation]

Hi alm,

Alas I don't have a 50 ohm terminated probe-tip BNC adapter nor a feed through terminator so I initially used a 50 ohm resistive load, then not noticing significant differences, did not use it for the further measurements.  Will give it another look and buy adapters and these terminators.

Here's a link for other regarding classic Tek Circuit Series textbooks.  Scanned and free.

http://www.slack.com/concepts.html

Examining it more intensely, there is a 1mV reduction in the over shoot, and minor ringing in now flattened out.  The rise time is interestingly longer by 0.5ns on all probes compared to using the ground clip.  Very odd result, but the signal quality is improved, but not much.  Will post photos when able.

Over shoot will result in a faster (apparent) rise time, although I'm not sure if 1mV over shoot explains 0.5ns rise time difference. I would definitely trust these measurements over measurements with a long ground lead, those things shouldn't be let anywhere near high-speed signals (unless your scope has an extremely low input capacitance, like active or lo-Z probes). The usual way is with a probe-tip to BNC adapter, preferably with internal 50 ohm termination, otherwise with feed-through termination between it and the generator.

[AndersAnd]

Rigol = RP 2200 [ shipped with 1052E ], 200 MHz rating, Rise time measurements are the tracing in blue.

One can say with certainty that the RP2200, rated at 200 MHz, is faster than the Yang Sun rated at 100 MHz.

Rigol RP2200's bandwidth is only rated at 150 MHz. However it looks like Rigol originally rated them at 200 MHz [hence the name RP2200.

The funny thing is the RP2200 User's Guide that came with my Rigol 1052E from 2009 has two tiny stickers on them that says 150MHz and 2.3ns for 10X bandwidth and 10X rise time respectively.
Below the 150MHz sticker it originally said 200MHz and I think it says 1.7ns below the 2.3ns sticker.

http://www.rigol.com/prodserv/DS1000E/attachment/?act=view&itemid=1

[saturation]

Thanks AndersAnd.   I wonder if the materials they use now downgrade the capabilities?

From my probe datasheet, enclosed.

[Stonent]

I have a set of the 2 for $10 100MHz probes that the adjustment thing fell out so now on one probe, I can't do the x10 adjustments any more.

[AndersAnd]

Thanks AndersAnd.   I wonder if the materials they use now downgrade the capabilities?

How old are your RP2200 probes? I bought my Rigol 1052E with the RP2200 probes in June 2009.
Are you probes older than that?

Or maybe they just forgot to put the stickers in your user's guide. Or maybe they later found out the probe couldn't live up to the 200 MHz BW they originally specified and just put stickers in the manual instead of improving the product to live up to the specs originally planned. I don't think these probes were ever sold with any scopes above 150 MHz BW anyway. Rigol 1152E-EDU with 150 MHz BW is sold on the Chinese market, with these RP2200 150/200 MHz probes too I think.

I just attached a scan of the spec sheet in my Rigol RP2200 User's Guide.
Notice the 150MHz and 2.3ns stickers on it. You can see some of the 200 below the 150MHz sticker and when I hold it up against the light I can see some of the 1.7ns too.

[Martini]

I just ordered a set ($ 4.17) and thought I would ask my question here...

The probes are rated at 100 MHz at 10x and 6 MHz at 1x. It's the same (or close) for every probe. Someone cares to explain me (in simple terms ) why there is such a dramatic difference in bandwith between the two modes?

[TheSteve]

I just ordered a set ($ 4.17) and thought I would ask my question here...

The probes are rated at 100 MHz at 10x and 6 MHz at 1x. It's the same (or close) for every probe. Someone cares to explain me (in simple terms ) why there is such a dramatic difference in bandwith between the two modes?

Dave would be happy to explain it:

[saturation]

It has to do with capacitive loading by the probe cables on the circuit being tested; when you add an RC network to the probe you can compensate for the cable load to some extent, that's why there are different rated probes and ultimately passive probes have a limit to their usability.

What actually can be done in compensation depends on the make of the probe. 

From the formula  bandwidth in Hz = 0.35/rise time in seconds

substitute to the datasheet below:

0.35/50ns = 7 MHz

I just ordered a set ($ 4.17) and thought I would ask my question here...

The probes are rated at 100 MHz at 10x and 6 MHz at 1x. It's the same (or close) for every probe. Someone cares to explain me (in simple terms ) why there is such a dramatic difference in bandwith between the two modes?

[Martini]

The probes are rated at 100 MHz at 10x and 6 MHz at 1x. It's the same (or close) for every probe. Someone cares to explain me (in simple terms ) why there is such a dramatic difference in bandwith between the two modes?

Dave would be happy to explain it:

Brilliant!

But then, can you have a x1 only probe with decent bandwith?

[vladk]

you can build your own cheap active FET probes, they are good enough up to 500Mhz.
http://welecw2000a.sourceforge.net/docs/Hardware/Aktiver_Tastkopf_mit_OPA659.pdf
I know the pdf is not in english, but in principle all you need to know is the schematics

Hmm... There are people exist who are not experienced enough in this particular topic of DIY.
Could you please be so kind to help with a link to an english version of that PDF or, may be better, to a source of affordable knowledge which will help to consider re-building the construction from the scratch?

[vladk]

At least, I would like to know - are those probes have adequate quality for the price?

https://www.aliexpress.com/item/new-x1-x10-P6200-200MHz-Oscilloscope-Clip-Probe-For-Tektronix-HP-FREE-SHIPPING/32394762214.html?spm=a2g0s.9042311.0.0.BcuaFr