Power - Triode ·Triode
Classic directly heated low-mu audio power triode developed for high-quality Class A amplification. Low plate resistance and roughly 40 W plate dissipation support transformer-coupled single-ended operation, with published output typically in the several-watt range.
Solid-plate directly heated 300B audio power triode. The supplied Emission Labs sheet was read for filament data, maximum ratings, representative operating points, gm/rp/mu, output conditions, capacitances, and rectifier filter conditions as applicable.
Medium-shell UX 4-contact
General specifications
Properties common to every published source and operating point.
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
1 physical section, each with unique specifications.
Section 1
Promoted fields audited from printed ratings/characteristics; remaining published values preserved as parameters.
Source-dependent data
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.
Data set 01
Published operating points and test conditions from this source.
HeaterOrFilamentVoltage
5 V
HeaterOrFilamentCurrent
1.2 A
Typical Plate Voltage
300 V
ClassA;Audio
Typical Plate Current
60 mA
ClassA;Audio
Data set 02
Published operating points and test conditions from this source.
Typical Plate Voltage
300 V
TypicalGridVoltage
-61 V
Typical Plate Current
60 mA
Grid Cathode Capacitance
17 pF
PlateCathodeCapacitance
11 pF
GridPlateCapacitance
7.5 pF
Data set 03
Published operating points and test conditions from this source.
Plate Current
50 to 85 mA
Plate 303 V; Grid -58 V
Power Output
5.5 W
Plate 303 V; Load 2.4 kohm; ClassA;OneTube
Negative Grid Voltage Maximum
220 V
Data set 04
Published operating points and test conditions from this source.
Filament voltage
5 V
Filament current
1.3 A
Plate resistance
700 ohm
ClassA
Amplification factor
3.9
ClassA
Transconductance
5600 uS
ClassA
Plate voltage
300 V
ClassA
Plate current
56 mA
ClassA
Grid voltage
-58.5 V
ClassA
Grid-plate capacitance
15 pF
Grid-filament capacitance
8.5 pF
Plate-filament capacitance
4 pF
Data set 05
Published operating points and test conditions from this source.
Plate Current
60 mA
Plate 300 V;Grid -61 V
GridCapacitance
17 pF
Plate Capacitance
11 pF
Grid To Plate Capacitance
7.5 pF
Data set 06
Published operating points and test conditions from this source.
Filament voltage
5 volt
Filament voltage 5.0 volts, a.c. or d.c.
Nominal fi l a m e n t current
1.2 amperes
Nominal fi l a m e n t current 1.2 amperes
Plate current
60 milliamperes
Plate current 60 milliamperes
A m p l i fi c a t i o n factor
3.85
A m p l i fi c a t i o n factor 3.85
Plate resistance
700 ohms
Plate resistance 700 ohms
Grid to plate transconductance
5500 micromhos
Grid to plate transconductance 5500 micromhos
operating plate current are shown in Figures
7 volt
operating plate current are shown in Figures 7, 8 and 9, for a plate voltage of 350 volts.
Pm, and harmonic levels, F
2
Pm, and harmonic levels, F2m and Fsm, for each point in both the curves and the table, is numer
Maximum plate voltage
450 volt
Maximum plate voltage 450 volts
Maximum plate dissipation
40 watts
Maximum plate dissipation 40 watts
Maximum plate current of average tube for fixed grid bias
70 milliamperes
Maximum plate current of average tube for fixed grid bias 70 milliamperes
limited to a maximum value of
70 milliamperes
limited to a maximum value of 70 milliamperes, so that tubes having plate currents higher than