it's a high voltage power supply, 4 kV/50 mA (max of 2 kV from ground, but the output is floating so you can do ±2 kV for a total of 4), and it's from an era where they advertised it being fully solid-state as a big selling point
and honestly that is a big selling point now, too; getting old equipment that uses tubes is always a pain because sometimes the tubes need replacing and sometimes they're ones that you can't get anymore
would love to have the schematics for it
-F
that flyback transformer is the source of the ticking i mentioned earlier, by the way. under no load it operates at about 1~4 Hz depending on the set voltage, making a tick every time it switches, and as the load increases it ticks more, up to a maximum of something around 3~4 kHz (by our ear, anyway--we don't have perfect pitch so this is a very rough estimate)
it's quite something to look inside
-F
maybe we'll try to reverse engineer it sometime
it's not that complicated a thing; the dials on the front are just decade switches for resistances (and the 1s digit is a potentiometer for fine adjustment), that'll obviously just be a divider in the feedback network (probably a kelvin-varley divider?)
the converter itself is an enormous flyback--i do mean enormous, the flyback transformer is about the size of a box of tissues--running in a variable frequency mode
-F