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.
It was of the early dull emitter valves to be introduced by M-OV who were the first manufacturer to introduce thoriated tungsten filaments. This introduction followed intensive research from 1919 onwards. The use of the V shaped filament with tension spring was new as was the flattening of the anode cylinder and grid helix.
Unlike our other LS5 this exhibit retains its paper label.
The BBC stamp is the earliest type that was current from 1/11/1922 to September 1924, so this exhibit is from an early production batch.
The paper label on the base shell. The pins are of two part construction.
A side view of the anode with the spring for the filament above.
The broad face of the anode and the top of the hoop grid support.
A close-up of the grid.
The base with M-OV Co Ltd embossed upon it.
The balloon envelope is 56 mm in diameter and, excluding the B4 base pins, is 108 mm tall.
References: 4051 & 1004 Type LS5 was first introduced in 1923.