Sensibly equivalent¶ to:
The 12AU7 is a double triode with separate cathodes. An amplification factor of 17 is quoted. The 6C4 is half of the 12AU7.
The getter is to the side and so the top of the envelope is clear glass.
The face view of one of the anodes.
The thin glass tube envelope is 20 mm in diameter and the length excluding the B9A base pins, is 48 mm.
References: Data-sheet & 1040. Type 12AU7 was first introduced in 1951.
Absolute Maximum Operating Conditions¶
Updated February 01, 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