The 12AU7 is a double triode with separate cathodes this example carries the alternative Type designation of ECC82. Also on the glass are the words Made in India.
An amplification factor of 17 is quoted. The 6C4 is electrically one half of the 12AU7.
The twin triode sections. The mica sheets look to be double thickness as one would expect to find in the special quality types for airborne and industrial applications.
Face view of one anode. Each section has an anode dissipation of 2.5 Watts and so the anode is blackened to form a better radiator.
The thin glass tube envelope is 20 mm in diameter and the length excluding the B9A base pins, is 47 mm.
References: Data-sheet & 1040. Type 12AU7 was first introduced in 1951. See also1951 adverts.
