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.This exhibit was made for the UK Air Ministry and has this identification on the base cap.![](../pics/aai0667a.jpg)
The original valve identification on the glass.![](../pics/aai0667b.jpg)
The old stores code of 10E/352 appears on the base cap.![](../pics/aai0667c.jpg)
The NAPL logo - a testing station?![](../pics/aai0667d.jpg)
The perforated anode screen and below and above the screening continues. 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. |