Octal beam tetrode often triode-strapped for similar applications — different structure (beam tetrode vs true triode) and higher mu when triode-connected
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Anode Voltage (max DC)550V
Peak Anode Voltage (max)Peak Anode Voltage (max)2,000V
Anode Dissipation (max)Anode Dissipation (max)12W
Cathode Current (max)Cathode Current (max average)100mA
Typical Operating
Notes
Originally designed for vertical-deflection output in 525-line, 30-frame TV systems. Maximum ratings for this service: Va=550V DC, Va_peak=2000V, Vg_peak=-250V, Ik_peak=350mA, Ik_avg=100mA.
The Class A amplifier operating point (Va=250V, Vg=-28V, Ia=40mA) is the recommended audio operating condition.
At grid volts = -38V with Va=100V, plate current for matching is 10 mA. Grid voltage for plate current = 125 mA at Va=100V, Vg=0V.
Low mu (6.6) means very low plate resistance (1200 Ω) yielding excellent damping factor when used as an audio output stage — desirable for direct-drive loudspeaker coupling.
Indirectly heated with unipotential cathode — can share a common 6.3V heater winding with signal tubes.
Pa_max of 12W allows approximately 3-4W of single-ended Class A audio output depending on load impedance and operating point.