The 5814A is a medium μ double triode closely related to the 12AU7 but made to a mil spec especially for electro insulation.
Current information gives the valve as now being made by Philips ECG in the USA.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 47 mm tall.
Reference: Data-sheet. Type 5814A was first introduced in 1954.
Absolute Maximum Operating Conditions¶
Updated January 27, 2013. shape:thin.glass.tube construction:all.glass type:double.triode age:1950.1960 base:b9a heater:6.3v pins:9 pin:1.a pin:2.g1 pin:3.k pin:4.h pin:5.h pin:6.a pin:7.g1 pin:8.k pin:9.hct