I have swapped the "old" Compton power supply for the thin planes (Fug HCE 7-125) for the new one with enough range to power the thick plane (Fug HCE 7-350, which has 350 V max). There is a conflict between the D-connector for communication on the back of the new unit and a rail in the slow controls crate; before we can run the unit installed flush in the crate we'll have to drill out a little section of the rail.
When set to "internal control" with the NIM output to a voltmeter, the voltage levels out at around 100V and the "current-limited" LED illuminates. When set to external control, the unit responds to the EPICS GUI in a sensible way. It seems that, like the 7-125, the 7-350 takes an set point of 255 = 0xff = "full scale", so that
set point voltmeter 25 35 V 50 70 V 60 83 V
or thereabouts.
In "internal control" mode, the range of control on the voltage-control screw feels pretty reasonable, but the current-control screw (once current limiting kicks in at about 100V out) only adjusts by about 1V/turn. Assuming all the signal goes into a 10 MOhm voltmeter input this is 10 uA current limit; this is such a tiny fraction of the 20 mA output rated on the case that there must be some funny business happening here.