The VT62 has a directly heated thoriated tungsten filament and was designed to have an anode dissipation of 50 Watts. Our other VT62 has a carbon anode, whereas this has a metal anode like the American 834. The latter being fitted with a UX4 base cap.
The anode and control grid both have a top cap connection in order to allow the valve to operate at high frequency.
The valve is a 1930s design. Probably based on the M-OV type DET12 of 1936/7 and the original types had the carbon block anode. It is also possible that the earlier RCA type 834, with the UX4 base, was the design influence. and this exhibit was marked for Air Force use (VT prefix), the Navy also had a version of the valve and when the Common Valve designations appeared the valve was still in use.
The A M and crown indicating an Air Ministry valve. The maker is Slater and the valve was made in the USA.
The anode supported from the top connection and the grid has both supports connected to the top cap rod.
The helical grid winding with the thoriated tungsten filament within has a greater pitch. The filament connects at to top to the central support.
The pinch and looking up into the anode shows more of the grid and filament.
The balloon envelope is 66 mm in diameter, and excluding the B4 base pins is 148 mm tall.