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
Notes
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