Pin 1 is the metal shell and internal shield connection, which should be connected to cathode for proper electrostatic shielding. On glass variants (6J7G, 6J7GT), pin 1 serves the same function.
The control grid (g1) is brought out to a top cap, not to a base pin. This was standard practice for RF pentodes in the mid-1930s to minimize grid-to-anode capacitance. The successor 6SJ7 eliminated the top cap by using improved internal shielding.
The grid circuit DC resistance should not exceed 1.0 megohm under rated maximum conditions.
The 6J7 was the international standard input-stage amplifier tube for nearly two decades, widely used in radio receivers, test equipment, and early audio amplifiers.
Pin Layout — Octal
1Shell and Internal Shield
2Heater
3Plate (Anode)
4
Socket-Compatible Tubes ⚠ Not electrically compatible