Sensibly equivalent¶ to:
Type 6J7 is a contemporary of the Magic Three and almost as ubiquitous. Although originally designed as a detector its linear characteristic and good internal shielding (cf. 6Q7) made it a natural choice for audio.
It was for two decades the international standard valve for audio amplifier input stages and audio systems generally. The Mullard-Philips type EF37A, for many years the standard British low-noise audio pentode, is really a 6J7G under another name.
The 12J7GT is the same valve but fitted with a 12.6 Volt heater.
The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 74 mm tall.
References: Datasheet, private communication & 1040. Type 6J7GT was first introduced in 1936.
Absolute Maximum Operating Conditions¶
Updated October 28, 2013.