Type 6J7 was originally designed as a detector, however, its linear characteristic and good internal shielding (cf. 6Q7G) 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.![](../pics/abv0003a.jpg)
The Osram brand label.![](../pics/abv0003b.jpg)
Looking up under the screen shows the additional screening plate above the pinch.The classic envelope is 38 mm in diameter and, excluding the IO base pins, is 99 mm tall.References: Private communication & data=sheet. Type 6J7G was first introduced in 1936. See also 1936 adverts. |