Sensibly equivalent¶ to:
The HA2 is a Marconi valve by M-OV that duplicates the American 955. The acorn valves were designed to have low capacitances and therefore work to higher frequencies than the normal valves.
Radio amateurs used them for work at 144 MHz after WWII.
The 955 was introduced by RCA in 1934 and the UK made devices did not achieve the success of the American product.
The tip to tip length is 32 mm and the envelope is 13 mm in diameter.
References: Data-sheet. Type HA2 was first introduced in 1936. See also 1936 adverts.
Absolute Maximum Operating Conditions¶
Updated May 08, 2022.