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.
Some other LS5 exhibits have the earlier metal base shell. This valve has the later Bakelite base and the etched Osram branding.
The vertical electrodes supported only at the pinch. The filament tension spring is empty as the filament has broken.
The Type designation is etched into the dome - possible as the evacuation tube is concealed in the base. The grid winding is rounded at the ends. The LS5A has a flattened end profile that moves the grid further away from the filament.
A closer view. The spring is fixed to the support by a clamped sleeve.
The balloon envelope is 56 mm in diameter and, excluding the B4 base pins, is 115 mm tall.
References: Data-sheet, 4051 & 1004 Type LS5 was first introduced in 1923. See also1923 adverts.
