This valve from Mullard has the identification LF and matched the HF Red Ring. The advert from 1924 matches the design of this exhibit with the single green ring.
The HF and LF are both bright emitter valves. The D.3 range, also introduced in 1924, have thoriated tungsten filaments are are known as dull emitters. The truly dull valves with oxide coated filaments begin with the D.06 valves.
The balloon envelope is 34 mm in diameter and, excluding B4 base pins, is 85 mm tall.
Reference: Data-sheet & 1003. Type LF was first introduced in 1924. See also 1924 adverts.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated September 04, 2018.