The 1LA4 is a battery audio output valve. With a 27,000 Ω load the output can be up to 115 mW. The 1AL4 is high impedance pentode. It is a Loctal based valve and the 1A5G is the octal alternative.
The bright anode is constructed from two plates shaped to form a cylindrical space for the other electrodes. The bright plates are stitched together around the support rods.
The all glass valve with its short solid hard pins is protected by a metal skirt. The locating spigot protects the evacuation tube. The glass base is moulded to form lugs for the metal skirt.
The silvered dome has the type designation etched onto it.
The wide glass tube envelope is 30 mm in diameter, and excluding the B8B base pins is 57 mm tall.
Reference: Data-sheet. Type 1LA4 was first introduced in 1940. See also1940 adverts.
