The LS5A from M-OV was a dull emitter valve designed for audio amplification.
The LS5A was introduced in 1924 with a metal base skirt. The LS5A improved on the original LS5 by having a lower impedance, which in turn allowed a greater output power to be delivered by the valve.
This exhibit is a later version and has a Bakelite base that also hides the evacuation seal. The 1928 advert shows the LS5A with the Bakelite base.
From the top of the envelope can be seen the cross section of the anode cavity and also the etched lettering.
The Osram branding took the form of this paper label.
The delicate spring for the filament can be seen but sadly the inverted 'V' filament is missing.
The balloon envelope is 57 mm in diameter and, excluding the B4 base pins, is 110 mm tall.
References: Data-sheet & 1043. Type LS5A was first introduced in 1924. See also1924 adverts.
