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Thrower 1043 reproduces the patent diagrams. The above diagram is from that source.
The first use of the pinchless construction was by RCA in 1935 with their metal valves on the IO base.
The Footless base was developed by the German Telefunken Company. The original patent by Dr K Steimel is dated 2 September 1936 and production valves date to about 1938 onwards. The Footless base was used extensively in WWII in Germany for valves in military equipment. As the construction diagram shows the valves based on the Footless base were of glass disc construction and featured a steel envelope. See also Footless Valves.
The numbering of the pins varies from source to source. Here I have adopted the pin allocation as given on the Philips data-sheets (diagram above) as they are consistent from data-sheet to data-sheet.
Below is the pin layout used by AVO in their Valve Data Manual Edition 20. It is NOT the layout used by Philips or exhibits within this museum. However, it is the layout for Y8A used by Keith Thrower.
The pin-outs below refer to the data researched by Keith R Thrower OBE.
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