Sensibly equivalent¶ to:
The 42 is an audio output pentode, with a low output rating, but when used in push pull a pair could deliver 18.5 Watts in class AB2.
Also on a UX6 base is the 2.5 Volt 2A5 that is electrically equal to the type 42. The Type 6F6 is electrically identical but on an IO base.
The construction of the electrodes is shown above. Note the control grid cooling fin sitting above the top mica.
See also 6F6 the octal version of this valve.
The balloon envelope is 53 mm in diameter and, excluding the UX6 base pins, is 118 mm tall.
References: Data-sheet & 1040. Type 42 was first introduced in 1936.
Absolute Maximum Operating Conditions¶
Updated April 06, 2015.