Sensibly equivalent¶ to:
The EM81 is a side viewing tuning indicator. This is a genuine Mazda valve but still the printing lies over the viewing face.
The triode like structure lies across the base of the valve with the electron stream travelling upward. The grid voltage change required is 9.5 Volts to sweep through all display variations.
From the side the poor printing is even clearer.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 58 mm tall.
References: Datasheet & 1040. Type EM81 was first introduced in 1956.
Absolute Maximum Operating Conditions¶
Updated November 18, 2013.