Similar power triode but 2.5V filament on 4-pin UX base — different base and heater voltage
6A3
Directly heated triode with same ratings and applications — NOT a drop-in due to directly vs indirectly heated cathode. Sylvania states 6A5G ratings and characteristics are identical to 6B4G except for Class A power rating.
Directly heated triode with identical ratings except different Class A power rating — NOT drop-in due to directly vs indirectly heated cathode
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Max Plate Voltage250V
Typical Operating
Anode Voltage (typical)Plate Voltage (Class A)250V
Grid 1 Bias VoltageGrid Voltage-45V
Anode CurrentPlate Current60mA
Anode Resistance
Notes
Sylvania datasheet (January 4, 1937, from RMA release #101). Described as heater-type power amplifier triode.
All eight pins are present but pin numbers 1, 4, and 6 are not connected. The tube is free from hum so no potentiometer is required for hum balance.
Grid circuit resistance: 0.5 MΩ max for self-biased arrangement, 10 kΩ for fixed bias.
Raytheon data lists as 'PR AMP CL A' with mu=4.2, gm=5350 µmhos, load=8000 Ω at Va=300 V, Vg=-18.
Sylvania datasheet gives mu=4.2, gm=5250 µmhos, ra=800 Ω at Va=250 V, Vg=-45 for Class A. Push-pull Class AB values: Va=325 V, Pout=10-15 W (fixed/self bias).
Pin Layout — Octal
1No Connection
2Heater
3Plate (Anode)
4
Socket-Compatible Tubes ⚠ Not electrically compatible