I bought an HMC8042 - nice compact unit that fits on a desk and is quiet and should suit my needs for most things albeit seriously expensive!
It came without its box which is odd - waiting for the seller to get back to me on that one.
Most uses for me are within 15V and 3A, so a single channel is fine, but I accepted the smaller outputs thinking if I needed to I could parallel this. I have a somewhat cheaper 9-15V 30A switcher if I want to run higher power amateur radio equipment, so this is for microcontroller projects and low power radio projects.
When I do parallel it and current is low it switches back and forth between sides (non-professional video of display here
https://photos.app.goo.gl/K8KK9Sj6e9tne6qK8). On the output on the scope I see the voltage move up and down as it does so. The current indication on the display includes what I think is referred to in the manual as "compensating currents between the channels", about 15mA varying.
I didn't screenshot the scope in DC mode. The deviations were noticeable above the noise (which I assume was picked up on my 50cm test leads and the amount of stuff effectively dangling off a non isolated USB oscilloscope). With the scope set to AC Coupled it looked like this:
![HMC8042 parallel operation low current hunting output? 1305020-0](https://www.eevblog.com/forum/index.php?action=dlattach;topic=295712.0;attach=1305023;image)
The load is shared once the current increases. I tested with radio transmitting into dummy load so pulling a couple of Amps.
Is this normal for any DC twin power supply operating in parallel mode at low current? So switching to a different one won't solve it? (Though I guess a less precise unit will always end up with one side taking charge as they can never be set the same unless it has a tracking mode?)
I can mitigate it by setting 10mV difference between the sides, then the higher voltage channel takes the strain until limit before the second channel kicks in.
Or I can decide that it arriving with no box is really bad on such an expensive bit of kit, A TTi 200D is cheaper and I wouldn't have to worry about running out of current. Given the induced noise around my desk, the noise figure is arbitrary (though the new office may improve that) and nice as the automation features are I'll never use them?
Thanks