The VR65 is a WWII military receiving pentode valve made for the RAF. The VR in the designation provides this information. Commercially this is an SP61 that was developed originally for television RF stages. The SP41 is the same electrically but has the pre-war 4.0 Volt standard heater.
With the grid at the top cap, this is the normal pattern for RF and IF amplifier valves of the period. Providing high gain in tuned anode circuit applications. For additional screening the valve is covered with an external metallisation.
The VR65 was used in air-borne radar particularly GEE.
This exhibit has lost almost all of the original zinc loaded screening paint. A small part adherers to the sticker above the base and there is a line near the top where it used to extend to.
The anode consists of a pair of plates mounted either side of the shaped grids. The closer to the cathode the grids are, the more they pass flat across the centre.
The rod in the foreground is not a grid support.
The strap connecting the two halves of the anode can be seen on the right of the blackened plate. The grid shapes are also easier to see in this image as are the relative grid pitches.
The rectangular cathode and above the top mica is a small cooling fin for the control grid.
The wide glass tube envelope is 30 mm in diameter and, excluding the MO base pins, is 81 mm tall.
References: Data-sheet & 1043. Type VR65 was first introduced in 1941. See also1941 adverts.
