TUBE: 300B
SOURCE: sheets/084/3/300B.pdf
FABRICANT: Western Electric (Bell System Practices, Section AB46.300B)
ANNEE: Issue 1, January 1950 (data sheet 5-49)
LANG: English (en)

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BELL SYSTEM PRACTICES — Transmission Engineering Data, Vacuum Tube Data
SECTION AB46.300B, Issue 1, January 1950, A.T.&T. Co. Standard
WESTERN ELECTRIC 300B — TRIODE POWER AMPLIFIER
DESCRIPTION: The 300B is a filamentary type triode designed for use as an audio-frequency power amplifier.
CHARACTERISTICS (quick):
 Filament Voltage = 5.0 volts
 Plate Current = 60 milliamperes (at Eb=350V, Ec=-74V)
 Power Output = 8 watts (at Eb=350V, Ec=-74V)
[300 B  TRIODE]

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GENERAL CHARACTERISTICS — ELECTRICAL DATA:
 Filament Voltage, A-C or D-C = 5.0 volts
 Filament Current = 1.2 amperes
 Direct Interelectrode Capacitances:
  Grid to Plate = 15 uuf (pF)
  Input = 8.5 uuf (pF)
  Output = 4.1 uuf (pF)
MECHANICAL DATA:
 Cathode = Coated Filament
 Base = Medium 4-pin with skew bayonet pin
 Mounting Position = preferably vertical; if horizontal, pins #1 and #2 in same vertical plane
MAXIMUM RATINGS, Design-Center Values:
 Plate Voltage = 400 volts
 Plate Current = 100 milliamperes
 Plate Dissipation = 36 watts
 Max Grid Circuit Resistance: Fixed Bias = 0.05 megohm; Self Bias = 0.25 megohm
TYPICAL OPERATING CONDITIONS — SINGLE TUBE AMPLIFIER, CLASS A1 (two columns):
 Filament Voltage A-C = 5.0 / 5.0 volts
 Plate Voltage = 300 / 350 volts
 Grid Voltage = -61 / -74 volts
 Peak A-F Signal Voltage = 61 / 74 volts
 Zero Signal Plate Current = 62 / 60 milliamperes
 Maximum Signal Plate Current = 74 / 77 milliamperes
 Transconductance = 5300 / 5000 micromhos (5.3 / 5.0 mA/V)
 Plate Resistance = 740 / 790 ohms
 Load Resistance = 3000 / 4000 ohms
 Amplification Factor = 3.9 / 3.9
 Maximum Signal Power Output = 6 / 7 watts
 Total Harmonic Distortion = 5 / 5 per cent
PUSH-PULL AMPLIFIER, CLASS A1 (values for 2 tubes):
 Filament Voltage A-C = 5.0 / 5.0 volts
 Plate Voltage = 300 / 350 volts
 Grid Voltage* = -61 / -67.5 volts
 Peak A-F Grid-to-Grid Voltage = 122 / 135 volts
 Zero Signal Plate Current = 100 / 170 milliamperes
 Maximum Signal Plate Current = 150 / 200 milliamperes
 Effective Load Resistance (Plate-to-Plate) = 4000 / 4000 ohms
 Maximum Signal Power Output = 10 / 20 watts
 Total Harmonic Distortion = 4.5 / 2 per cent
 *If filament on D.C., characteristics approx. same if grid voltage (from neg. filament) decreased by 2.5 V.

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[courbes seules — plate characteristics: Ip vs Plate Voltage (Ec=0..-140V), Ef=5.0V A.C.;
 and Ip vs Grid Voltage (Eb=100..450V)]

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[courbes seules — Plate Resistance vs Grid Voltage (Eb=100..450V); Amplification Factor vs Grid Voltage]

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[courbes seules — Transconductance vs Grid Voltage (Eb=100..450V);
 Power Output & Total Harmonic Distortion vs Load Resistance (Eb=350V, Ec=-74V, input 74V peak)]

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[outline drawing — ST19 BULB; dimensions 2-7/16" / 1-9/16" / 1-13/16" / 5-5/16" / 6-1/2" max.
 A4-72 MEDIUM 4-PIN BAYONET BASE.
 Base diagram (4-pin, 47 deg skew): pin1=GRID; pin2=PLATE; pin3=FILAMENT; pin4=FILAMENT (plane of filament).
 STRUCTURE: GRID, PLATE, FILAMENT only -> single grid = TRIODE.
 Western Electric / Bell Telephone Laboratories.]