The PM5D is a battery operated directly heated triode.
The etched lettering gives the filament voltage as 6 and the maximum anode voltage as 150.
The electrodes are obscured by the coating but it is possible to see the construction looking up from the base. The anode lies horizontally and the grid wires extend to outside of the anode box.
The balloon envelope is 45 mm in diameter, and excluding the B4 base pins is 88 mm tall.
References: 1931 data-sheet & 1043. Type PM5D was first introduced in 1930. See also1930 adverts.
