The VT501 (Valve Transmitting 501) is a small low power VHF transmitting beam tetrode used by the RAF in WWII, it was also known as the CV1501 after 1941 when the CV Register was introduced to unify the UK Government's valve procurement.
The method of assembly can be seen through the clear envelope. The supports would be fitted into the pinch stem and the glass heated and compressed to form the pinch. The supports would then be cut and shaped. The electrodes, separately assembled by hand in a jig and secured between the mica discs, would be spot welded to the supports. The insulated heater wire passes through the cathode tube six times. The single wire is then welded to the supports.
This image was enhanced in an attempt to make the grids more visible. It does show the anode shape to good effect.
The anode connected to the top cap from both sides. The control grid has a heat radiating fin attached.
The classic envelope is 32 mm in diameter and, excluding the IO base pins, is 89 mm tall.
