I have received the unit (haha) today, but I won't be able to test much today. First impressions:
+ The 2A rating on the USB port is correct. It shuts off hard at 2.2A and recovers instantly once the load is removed.
+ Noise seems pretty low, even on the USB port. It might actually be a linear supply for that "Channel".
+ Set and Readback accuracy on the voltages is pretty good. Set voltages are off by mostly less than 2 mV, Readback is around the same.
+ I did not see an overshoot when activating the output with a load present or when adding a load and having current limiting kick in.
+ The user interface is great. There's a few typos here and there ("Templet" = "Template") and language selection is possible in two spots for some reason. But the overall workflow is intuitive.
- Channel 2 outputs a voltage of -243 mV when turned off. In parallel mode this drops to 127 mV, possibly because Ch1 takes some of it. Ch1 is at -11 mV, Ch3 at 0.03 mV . Changing settings doesn't seem to have an effect. The short-circuit current in this state is -0.5 mA. I'll see if that's still there tomorrow, it's not something I like to see. The maximum allowed reverse voltage for many logical gates is 0.5V, so it's about half of that. I don't know about more sensitive low voltage circuits though.
All in all I'm not fully happy yet. Pseudo-Channel 4 could at least have an on-off-switch, I already missed that when connecting a USB connector for measurement. The negative voltage when turned off is at least an annoyance. There's also no relay click when switching outputs, just when chhanging ranges, which indicates that the outputs are permanently connected.
I went to the Embedded World, an exhibition that is held this week. I spoke to the representatives from Siglent and GW Instek about their selection of power supplies, specifically mentioning that I just ordered the UNI-T for its 5A/Ch output rating. The responses were:
- Siglent: We have a new model planned for this year that will feature a higher output current, but we don't know when it will be released.
- GW Instek: It's on their list. I filled out a form to specifically request that and possibly bump up the priority.
Both said that multiple customers came with that specific request. So maybe UNI-T will soon have some competition.