Data: MediumMedium quality — at least 60% of universal parameters and pins are present, but some key data is missing. Verify specific values against datasheets before critical use.
Anode Voltage (max)DC Plate Supply Voltage (max)770V
Peak Anode Voltage (max)Peak Positive Plate Voltage7,000V
Screen Voltage (max)Screen Voltage (max)220V
Anode Dissipation (max)Plate Dissipation (max)24W
Notes
21HJ5 (21.5V/0.6A heater) and 30HJ5 (30V/0.45A heater) are heater-voltage variants, identical except for heater characteristics.
Pins 6 and 8 are internal connections marked 'Do Not Use' — socket clips for these pins should be omitted to improve insulation.
Grid No.1 and Grid No.2 each have dual base pins (3+11 and 5+9 respectively) for improved cooling. Grid No.3 (beam plates) also has dual pins (4+10).
An adequate bias resistor or other means is required to protect the tube in the absence of excitation.
Originally designed for TV horizontal deflection with peak plate voltages up to 7000V, but widely adopted by DIY audio builders as a triode-connected output tube.