Sensibly equivalent¶ to:
The CV2570 is a military marked 210HF. This battery triode was designed for HF use, and in those days a few MHz was high frequency. It is a receiver valve from the days of the TRF (tuned radio frequency) receiver.
The balloon envelope is 40 mm in diameter and, excluding the B4 base pins, is 79 mm tall.
References: Datasheet & 1040.
Absolute Maximum Operating Conditions¶
Updated October 13, 2013. 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