Brans lists as equivalent (same table IIIf group with 12A4 and ECC34). Verify pin compatibility before substituting.
Electrical Specifications
Section 1 — Medium-Mu Triode (Oscillator)
Absolute Maximum
Anode Voltage (max)Max DC Plate Voltage350V
Anode Dissipation (max)Max Plate Dissipation1W
Cathode Current (max)Max DC Cathode Current50mA
Heater-to-Cathode Voltage (max)Max Heater-Cathode Voltage200V
Notes
Dissimilar dual triode: Section #1 (medium-mu oscillator, pins 4/5/6) has mu=22.5; Section #2 (medium-mu amplifier, pins 1/2/3) has mu=15.4. Both sections are medium-mu but with substantially different plate resistance and transconductance.
Section #2 Pa_max of 10W is for short interval only (two seconds maximum) so as not to damage the tube.
Heater positive with respect to cathode DC component must not exceed 100V.
Brans vademecum groups the 6DN7 with the 6FJ7, 12A4, and ECC34.
Pin Layout — Octal
1Grid (Unit No.2 - Amplifier)
2Plate (Unit No.2 - Amplifier)
3Cathode (Unit No.2 - Amplifier)
Socket-Compatible Tubes ⚠ Not electrically compatible