The RS237(I) is a 100 watt triode with a mu of 12 made by Telefunken for the German military in WWII. This example from 1937 has the "I" suffix indication a change in construction from the original tube. There was no electrical difference. This example is marked D.R.P. for Deutsches Reichspatent.

Length = 7.00" Diameter = 1.87"
Max voltage = 1000
Max current = 80 ma
Fil voltage = 10
Fil current = 3.3 amps         GOTO INDEX