Hi gitm!
For the 2512G you'll note how at 1Vpp it is recognizable as a 20MHz square wave. At 2Vpp is starts rounding off into a near perfect, but distorted sine wave. At 3Vpp I really doubt you could tell it was supposed to be a square wave if you didn't know it was supposed to be a square wave.
Thanks for testing!
I don't have an amplitude-adjustable SG for this voltage range.
But I have a different conclusion!
It is as I said before (also to jebem above).
The difference is with the "relay click", i.e. with the vertical sensitivity changing from 200 mV to 500 mV (in 1x mode).
Between 2 and 3 volts there is no difference in details in your pictures, the signal is just stretched because of higher amplitude (See attachment).
And the remedy for me is also clear.
Just take 10x probes and you're at 200/300mV at the inputs.
That's probably how it's supposed to be used.
It's a toy after all.
EDIT: Attached the resampled 3 V image H: 320px -> 240px. It's exactly the same signal shape as in the 2 V picture.
Glad you're enjoying the journey. Exploring is fun. Remember when you asked if I could articulate in a comprehensible way what I meant by the BW definition including "waveform distortion"? You tell me, did I? BTW, you never said it had to be pain free.
A side note: some op amp datasheets recognize distortion as being the limiting factor for their gain bandwidth product. Food for thought. Many op amp datasheets will list harmonic distortion figures and graphs. And if you want to chew on that thought, check out this 10 minute video from Texas Instruments....
https://www.ti.com/video/4078676441001Re: your setup with 20dB attenuator: signal at the scope input is Small Signal less than 1Vpp. You'll find this on op amp datasheets as the "Small Signal Response" usually shown with a hand selected best figure (not only do scopes lie but some datasheets lie/mislead too) and/or small_signal_response/frequency graph. But it can and often does differ from "Large Signal Response".
But, looking at your screenshot, I think I see reflections somewhere on the setup. Just a guess, but they might be between the signal source and the input to the attenuator where there is a discontinuity in impedance. The run between attenuator to scope input looks short enough that reflections might smear out becoming less noticeable. Again, nothing more than a guess.
If you really want to know, you could try decreasing sq. wave frequency (keeping the edge rise time and maxing amplitude) to make the signal stretch out and measure the ringing frequency with cursors. I've done this with the 2512G using the internal signal generator at 1kHz and successfully measured ringing up to 90MHz. You don't need vertical accuracy to measure that ringing frequency and all signals will devolve to sine waves anyway. Once you've got a decent ringing frequency estimate, you can calculate it's wavelength (remember that the cable/connectors have a velocity factor -- on part datasheets for cable or if you don't have it assume 0.67 to get you in the ball park). The wavelength will be in the
ball park for the length of run that ringing originates, assuming only one thing is ringing.
ETA: I forgot to mention that a "length of run" has two ends and reflection can occur on one or both ends depending on impedance mismatches. Frequency can be "interesting" as a result. W2AEW (I think is a member of this board?) has the best video explanation I've seen on it
https://youtu.be/g_jxh0Qe_FYPeace out.