Need schematic or technical info on EBERLINE PAC-ISAGA alpha radiation meter
 

I recently picked up an Eberline model PAC-ISAGA Alpha Counter radiation
meter and I need to know what to set the high voltage to.
This unit has a scintillation probe to measure alpha particles. This probe
is different from the Geiger/Meuller probe for gamma measurements.
All I was able to find was an army parts list for the external case.
What's interesting about this unit is that it appears to have a serial
number of 001 engraved on the top cover.

Any info would be greatly appreciated.

Thanks,
Larry VE3LRI