A Siglent SDM3045X DMM bug?

[Amaruk]

I love my new Siglent SDM3045X DMM! But I just noticed something strange on it. I know that over four years ago there were reports of this model having problems measuring the DC offset of an RF signal at 1kHz. I thought newer SW and HW versions had made this problem go away a long time ago. In a way that is true. The difference between then and now is that newer SW versions for this model have an (undocumented) DC filter function that will solve the problem but it is turned off by default.

But I happened to discover that if the DC filter is off you can also get the correct reading if you change the DC offset up and back down while the RF signal is still on… very strange!

Below is a video I shot that shows the problem and how you can get around it by adjusting the offset up and back down or turning the filter on.

What do you think is going on in the DMM here? Anyone else have this issue?

Link to my video:
https://youtu.be/g6it3cXnVq0

Here is a link to the initial report by TRX Lab from early 2017 about this exact issue (it starts around the 58 minute mark):
https://youtu.be/K09BLgyk9Hg?t=3492

For those interested, here is a link to a 2004 white paper from Fluke that I found that discusses the difficulties of of AC+DC measurements:
https://us.flukecal.com/literature/articles-and-education/electrical-calibration/white-paper/making-accurate-dc-voltage-meas

Update: I heard from Siglent that the filter I show in the video must enabled for these measurements (not available on early SW versions). Thus, the hysteresis effect shown in my video by increasing and lowering the offset is more of a curiosity as the intended use is to have the filter enabled. For the price of this DMM we should not complain. I am just curious if more expensive bench DMM's also have a filter that the user must enable manually in situations like this. Does anyone know?