The VT62 transmitting valve, has a directly heated thoriated tungsten filament and has the electrodes sealed into a glass pinch. This exhibit carries the Radiotron brand of RCA and the RCA Type of 8019.
The high operating voltage leads to the positioning of the anode connection at a top cap. The grid is also moved to 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.
The stitched anode is spot welded to the support that is sealed into the top of the envelope. The control grid connects to the second top pin and also has no lower fixing.
Looking along the grid axis. At the base are the two supports for the double helical filament.
A closer view of the construction.
The filament consists of a thick central support to the top with the thoriated tungsten wire double helix running from top to bottom.
In this image of the filament base the central rod is the support to the top with the outer rods connecting to the filament ends. The fixing of filament to support looks to be by welding.
The balloon envelope is 67 mm in diameter and, excluding the B4 base pins, is 151 mm tall.
