The M-OV V24 valve was a development of the 'R' type aimed at improving the high frequency performance. The bright emitter V24 was designed around 1919 and was used as an RF amplifier with a filament current of 0.7 Amps. The anode voltage would have been in the range 24 to 50 Volts. The V24 itself being an indication of the use of standard 24 Volt supplies of the type used on board ship for lighting.
The grid and anode connections are to side pips on the envelope and the single strand tungsten filament runs from cap to cap, with a spring for tensioning. The construction is co-axial with the helical wire grid surrounding the filament and fitting within the cylindrical anode. In this valve the 'U' shaped glass support holds two stout wire rods that attach to the anode and grid respectively. These electrodes are thus only supported at one end.
This exhibit is branded Osram - the commercial brand from M-OV, and came with an ebonite base.
The V24 mounted on the home-made ebonite base.
The BBC stamp is of the second type and dates this valve to between September 1924 and 1927. Inside can be seen the filament tension spring.
The green paint on one side contact identifies the anode. The filament is complete.
The thin glass tube envelope is 17 mm in diameter and, tip to tip is 72 mm tall. Across the side pips measures 26 mm.
References: Data-sheet & 1003. Type V24 was first introduced in 1919.