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Possible serious bug in RTO1024 or RTO1000 series scope?
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JohnG:
I get the same problem as above, using a single source with a splitter. If the probe attenuation is set to 1x, there are no problems. If it is set to a higher value, then the delay shift error described above occurs.

It also occurs even if I use the trigger output of the generator connected to the external trigger input on the scope, with the same symptoms described above.

The time shift error is also about 600 ns every time, no matter what the input signals and source signals.

It can happen on any channel, no matter what the trigger source is.

It is such an odd error, I initially assumed I had a setup problem, bad connector or something. When I finally dug in, I found it was a scope error. If I do the exact same setup on my other Lecroy scope, I have no problem.

John
nctnico:
Is this purely related to the external trigger? Maybe this problem is related to the recovery time of the external trigger input somehow. What happens if you use a regular channel instead of the external trigger?
JohnG:

--- Quote from: nctnico on July 06, 2022, 03:21:55 pm ---Is this purely related to the external trigger? Maybe this problem is related to the recovery time of the external trigger input somehow. What happens if you use a regular channel instead of the external trigger?

--- End quote ---

No, I first noticed it using a channel trigger.

The problem occurs on any channel that has the probe attentuation factor set to some value other than 1 V/V. In fact, the range of vertical scale factors for which the problem occurs increases for higher scale values.

For example:
2V/V, problem occurs at 10 mV/div
5V/V, problem occurs at 20 mV/div through 50 mV/div
10V/V, problem occurs at 40 mV/div through 200 mV/div
20V/V, problem occurs at 100 mV/div through 1V/div.

I can make it occur on any channel, and it follows the above pattern. It does not appear to be affected by signal amplitude, and the measured delay is always 600 ps when the problem occurs. This is using the scope measure delay function, so it a few ps longer than 600, same whether measured on rising or falling edges.

Only happens with inputs set to 50 ohm Zin.

I have replicated the results with rectangular pulses from my pulse generator.

It does not happen when I remove the cables from the RTO scope and put them on my SDA6020.

John
nctnico:
I don't think this is a bug but something is broken in your oscilloscope. I'm wondering what R&S has to say about this.
JohnG:

--- Quote from: nctnico on July 06, 2022, 04:37:08 pm ---I don't think this is a bug but something is broken in your oscilloscope. I'm wondering what R&S has to say about this.

--- End quote ---

I will find out soon enough. I have had it repaired 1.5 years ago at considerable expense, due to some mainboard communication error.

It is a very odd problem.

John
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