The valve was designed for class A audio amplification in telephone equipment where long life was very important.

The thin glass tube envelope is 19 mm in diameter and, excluding the B9A base pins, is 57 mm tall.

Filament Vf 6.3 Volts / If 0.3 Ampere / Indirect / Specified voltage AND current AC/DC

Special quality valve designed for stability and long life.

Va<210, Pa<2.1W Ik<16mA.