Series-heater (600 mA) version of the EF184. Electrically identical sections — only the heater voltage/current differs (3.6 V at 600 mA vs 6.3 V at 300 mA).
3EJ7 is the American RETMA designation for the XF184.
Sharp-cutoff pentode — the variable-mu (remote cutoff) equivalent is the EF183/XF183.
Pin 6 is an internal shield (screen) connected internally — must be grounded for proper RF shielding.
Pins 1 and 3 are both cathode connections.
Brans Vademecum also lists YF184 as an equivalent.
Pin Layout — Noval
1Cathode
2Control Grid
3Cathode
Socket-Compatible Tubes ⚠ Not electrically compatible