ECC31

Small Signal Triode — Octal

Mullard

Known Equivalents & Substitutes

CV1285NR73

Similar Tubes (Not Drop-In Compatible)

6N7G

Similar type but different specs — mu 35 vs 32, ra 11k vs 14k ohms, heater current 0.8A vs 0.95A. Not a drop-in in critical applications

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Max Anode Voltage300V

Anode Dissipation (max)Max Anode Dissipation (per section)5W

Cathode Current (max)Max Cathode Current25mA

Heater-to-Cathode Voltage (max)Max Heater-Cathode Voltage50V

Max Grid ResistorMax Grid Resistor1.5MΩ

Typical Operating

Anode Voltage (typical)Anode Voltage250V

Grid 1 Bias VoltageGrid Voltage-4.6V

Anode CurrentAnode Current6mA

Anode ResistanceAnode Resistance14,000Ω

TransconductanceTransconductance

Capacitances

Grid-to-Plate CapacitanceGrid-to-Anode Capacitance3.4pF

Grid-to-Cathode CapacitanceGrid-to-Cathode Capacitance4pF

Anode-to-Cathode CapacitanceAnode-to-Cathode Capacitance1.9pF

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.95A

Notes

Common cathode — both triode sections share a single cathode (pin 8). Individual cathode biasing per section is not possible.
6N7G is often listed as equivalent but has different characteristics: lower heater current (0.8A vs 0.95A), higher mu (35 vs 32), and lower ra (11 kOhm vs 14 kOhm). Not a drop-in replacement in critical applications.
Half-screened envelope distinguishes it visually from the ECC32, which has a fully screened envelope and separate cathodes.

Pin Layout — Octal

1No Connection

2Heater

3Anode 2

4

Socket-Compatible Tubes ⚠ Not electrically compatible

References