Same 9A pinout and similar mu (~60), but different heater current (150mA vs 225mA series). Not interchangeable in series-string heater circuits. Sams Handbook lists as substitute for parallel-filament circuits only.
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Max Plate Voltage300V
Anode Dissipation (max)Max Plate Dissipation2.5W
Heater-to-Cathode Voltage (max)Max Heater-Cathode Voltage200V
Max Grid ResistorMax Grid Resistor (cathode bias)1MΩ
Typical Operating
Anode Voltage (typical)Plate Voltage250V
Grid 1 Bias VoltageGrid Voltage (approx., for Ib=10mA)-12V
Heater can be wired in series (12.6V, 225mA) or parallel (6.3V, 450mA). For 12.6V operation, apply voltage between pins 4 and 5. For 6.3V operation, connect pins 4 and 5 together and apply voltage between that junction and pin 9.
Internal shield connected between pin 3 (section 2 cathode) and pin 5 (heater). Capacitance specs are measured with this shield grounded.
Two sets of typical operating conditions are published: a high-current point at Va=250V / Ia=10mA (gm=5.5 mA/V, ra=10.9 kΩ) and a low-current point at Va=100V / Ia=3.7mA (gm=4.0 mA/V, ra=15 kΩ).
Max grid-circuit resistance differs between cathode-bias (1.0 MΩ) and fixed-bias (0.25 MΩ) operation.
Electrically identical to the 12AT7 (same mu, gm, ra, max ratings) but with higher heater current (225mA vs 150mA series) and higher max heater-cathode voltage (200V vs 90V). Designed for use in series-string transformerless TV receivers and test instruments with elevated heater-cathode voltage.
Pin Layout — Noval
1Plate (Section 2)
2Grid (Section 2)
3Cathode (Section 2)
Socket-Compatible Tubes ⚠ Not electrically compatible