Sensibly equivalent¶ to:
The 210HF is a dull emitter battery triode. It was designed as a detector in broadcast receivers, in the early 1930s. Cossor describe it as similar to the 210HL but with a greater gain.
The dome carries etched information including the Cossor name and that it was made in England.
The balloon envelope is 41 mm in diameter and, excluding the B4 base pins, is 84 mm tall.
References: Datasheet & 1040 Type 210HF was first introduced in 1928.
Absolute Maximum Operating Conditions¶
Updated January 15, 2018. shape:balloon construction:pinch type:triode age:1930.1940 base:b4 heater:2.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f