The Marconi V24 valve was a development of the 'R' type aimed at improving the high frequency performance. The 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 valve came in a cardboard box and has no BBC stamp and was probably a replacement valve made after the 1920's.
The anode is denoted by the green paint on the side cap. This example is unused and the paint is still clear. The filament strand can be seen at the centre of the grid.
The identification markings are etched into the glass envelope. This view shows the Marconi Valve lettering and the Patented and Made in England lines.
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: 1003. Type V24 was first introduced¶ in 1919.