The LS5 from M-OV is a triode designed, in 1923, especially for driving a loudspeaker and featured many developments in valve design. The LS5 had, for its day, a high anode dissipation of 10 Watts. The characteristics PDF is from 1926.
Our other LS5 exhibits have the earlier metal base shell. This valve has the later Bakelite base.
The oval anode with the grid support looped at the top. The filament top spring is empty as the filament has failed.
A view of the electrodes looking up from the base. The getter carrier is on the right.
The balloon envelope is 56 mm in diameter and, excluding the B4 base pins, is 112 mm tall.
References: Data-sheet, 4051 & 1004 Type LS5 was first introduced in 1923.