The EM81 is a side viewing tuning indicator and this exhibit was made by Philips in Holland.
The triode amplifier 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.
The coated screen where the fan shaped shadow is displayed.
Face view.
The voltage amplifier. The coiled heater, round cathode and grid supports can be seen together with the two mica electrode supports.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 57 mm tall.
References: Data-sheet & 1040. Type EM81 was first introduced in 1956. See also1956 adverts.
