Replying to myself. Farnell had a 10% off deal last week so I finally bought an ELC ALR3206T. It's a triple voltage power supply. CH1 and CH2 can independently output 0-32V up to 3A, can be connected in series to output 0-64V up to 3A, or be connected in parallell to output 0-32V up to 6A. CH3 can be set to output 1-15V and lacks current limiting.
First impression: It is small and neat and quiet. When the unit is lightly loaded the fan doesn't seem to run at all which means that it is dead quiet, even with the fan at full speed it's not too loud.
The user interface is not very good. The display is very slow to update, it takes a significant fraction of a second for the voltage and current displays to change if I connect or disconnect a load. The display is quite easy to read though, with large digits for voltage and current, and smaller digits for power (W) and an indication if the channel is voltage or current limited. I do not like the "keys" at all, it's just a touch sensitive panel with print for where they "keys" are so there is no tactile feedback. I already knew that the key panel would be like this from the product description, but I thought I'd mention it anyway. What I do like about the panel though is that it has separate keys to turn on or off each channel separately, and a common on/off key which turns of all channels if any channel is on, and turns on all three channels if all are off.
One thing I didn't realise ahead of time though is that the distance between the 4mm banana connectors is about 14mm, not 19.05 mm which is the standard, so things such as my BNC to banana adapter will not fit. Not a dealbreaker in any way, and I guess they needed to do that to be able to fit six connectors in such a small width.
It is a switching power supply and thus doesn't weigh very much at all. It's got a lot of connectors on the back that I probably won't use. There are connectors for the output of CH1 and CH2 on the back and inputs for external sense lines. There are is also a connector for an "analog remote", which can use either a potentiometer or a control voltage to set the voltage of CH1 and CH2. There is also a RS485 port and a USB port which shows up as a CDC-ACM serial port on Linux (and you can download a .INF from the manufacturers web page which when installed ought to make it show up as a serial port on Windows). Unfortunately there is no documentation of the serial protocol in the accompanying manual. I have mailed the manufacturer asking for documentation, but can't really expect a response until the Easter holiday is over.
If I measure the output voltage with a multimeter it's within 5mV of the setting on the PSU, well within the claimed 10mV accuracy. The output ripple seems to be quite a lot higher than specified though, but that could also be my scope probes picking up noise from the fluorescent lights in the office. As far as I can tell all three channels are completely isolated from the mains earth and the USB port.
So all in all I'm quite happy with the PSU so far. I wanted a small and quiet PSU with two channels that can output a positive and a negative voltage to power analog stuff with a decent voltage and current range, and one more channel to power digital stuff up to about 12V, and that is just what this PSU can do. I also want to be able to control the PSU from a computer and expect to be able to do that as soon as I receive some documentation of the USB-serial protocol.
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