Sensibly equivalent¶ to:
The PM1HL is an amplifier triode and it has external bronze metallising and a 2.0 Volt filament.
The electrodes are obscured by the coating on the envelope. The PM1HL was designed as a detector and general purpose valve and dates from 1931. It was intended to be used in domestic broadcast receivers.
The top of the envelope carries the identification, plus filament rating and maximum anode potential.
The balloon envelope is 39 mm in diameter, and excluding the B4 base pins, is 77 mm tall.
References: 1931 data-sheet & 1043. Type PM1HL was first introduced in 1931. See also 1931 adverts.
Absolute Maximum Operating Conditions¶
Thanks to Andy Cowley for supplying the above PDF datasheet.
Updated June 08, 2022.