Hi!
I’ve asked Siglent support but after a couple of responses the thread went cold. Maybe I’m being dumb but I’ve noticed that there’s a frequency (low, around 100Hz) where scope response changes a bit. Below and above it square input looks square. Right about it square input looks slanted.
I tried to do a very slow “sweep” and there’s small but visible change in the envelope. So, e.g. with a constant 600mV p2p input lower frequencies measure exactly that while higher ones measure 612mV, so ~2% diff.
Terminated 50Ohm cables (not that it matters at such a low freq) to be sure. Latest firmware, after full self-cal. Siggen itself seems allright, I have an ancient Tek scope and the siggen output looks Ok there with same input/same cables. Scope seems happy and fully functional otherwise, few years old though, out of warranty.
Has anyone else seen anything like that? Is this a normal behavior within the expected margin of error?
Thanks!
Yup, seen that for sure.
Did you try turning the little adjustment knob in your probe to calibrate it? Sometimes needs a small screwdriver. Here’s a reference:
https://www.elecrow.com/download/HowToCalibrate10xProbe.pdf
What I’m referring to is labelled ‘Cap Trimmer’. The document also has some waveform images that match your problem.
I have a Siglent and it looked like this at the dealership, then they adjusted the probe a bit, and then it was 100% fine.
Thanks but unfortunately this is not a probe cal problem. Note that the issue is seen even in a 50Ohm environment, no probes.