Sensibly equivalent¶ to:
The Osram HL210 was first introduced in 1928 and is a general purpose triode.
The etching on the face of the envelope is easy to read but hard to photograph as it is quite faint.
The etching on the dome is faint but with enhancement can be seen as brown. To the naked eye the lettering appears as a uniform grey.
The balloon envelope is 41 mm in diameter and, excluding the B4 base pins, is 76 mm tall.
References: Datasheet & 1043. Type HL210 was first introduced in 1929.
Absolute Maximum Operating Conditions¶
Updated June 09, 2012. shape:balloon construction:pinch type:triode age:1920.1930 base:b4 heater:2.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f