The SU2150P looks to be the predecessor of the SU2150A classic HT rectifier from Cossor. The screw top cap places its age in the mid 1930s. Indeed it may be the SU2150 and the ratings are taken for the SU2150.
The effective series resistance needs to be 100,000 Ω and the reservoir capacitor is limited to 0.25 μF.
Thanks to Bob Hopkins for sending the image.
The classic envelope is - mm in diameter, and excluding the B4 base pins is - mm tall.
Absolute Maximum Operating Conditions¶
Updated April 27, 2013. shape:classic construction:pinch type:rectifier.hw age:1930.1940 base:b4 heater:2.0v pins:4 pin:1.- pin:2.- pin:3.f pin:4.f pin:tc.a