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Voltage Pentode - High Frequency (single) ·Pentode

403A

Western Electric miniature pentode designed for high- and ultra-high-frequency amplification, combining useful gain with compact low-capacitance construction.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
B7G
Base pins
7
Nominal heater
6.3 V / 175 mA

Description

7-pin miniature pentode for amplifier circuits at high and ultra-high frequencies.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
B7G
Base pins
7
Nominal heater voltage
6.3 V
Nominal heater current
175 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
300000 Ω
Transconductance
0.005 S
Max plate voltage
180 V
Max screen voltage
140 V
Max plate dissipation
1.7 W
Max screen dissipation
0.5 W
Max cathode current
18 mA

Promoted fields mapped from printed maximum-rating and characteristic headings; additional published values preserved in parameter rows.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

2026 Western Electric 400s

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

  • Plate Current . . E, = E., =

    120 volts

    Plate Current . . E, = E., = 120 volts; . 7.5 milliamperes

  • Transconductance . { Cathode-Bias Resistor =

    200 micromhos

    Transconductance . { Cathode-Bias Resistor = 200 chms } . . 5000 micromhos

  • Heater Voltage, A-CorD-C

    6.3 volts

    Heater Voltage, A-CorD-C. . . . . . . . . . . . . 6.3 volts

  • Heater Current

    175 milliamperes

    Heater Current . . . . . . . . . . . . . . .. 175 milliamperes

  • Plate Voltage

    180 volts

    Plate Voltage . . . . . . . . . . . . . . . . . 180 volts

  • Screen Grid Voltage

    140 volts

    Screen Grid Voltage . . . . . . . . . . . . . . . 140 volts

  • Cathode Current

    18 milliamperes

    Cathode Current . . . . . . . . . . . . . . .. 18 milliamperes

  • Bulb Temperature

    120 centigrade

    Bulb Temperature. . . . . . . . . . . . ... 120 centigrade

  • Plate Voltage

    120 volts

    Plate Voltage . . . . . . . . . . . . 120 150 180 volts

  • Screen Grid Voltage

    120 volts

    Screen Grid Voltage . . . . . . . . . . 120 140 120 volts

  • Cathode-Bias Resistor

    200 ohms

    Cathode-Bias Resistor . . . . . . . . . 200 330 200 ohms

  • Plate Current

    75 milliamperes

    PlateCurrent. . . . . . . . . . . . 75 6.6 7.7 milliamperes

  • Screen Grid Current

    25 milliamperes

    Screen Grid Current. . . . . . . . . . 25 2.1 24 milliamperes .

  • Plate Resistance

    0.3 megohm

    Plate Resistance . . . . . . . . . . . 0.30 6.40 045 megohm |

  • Transconductanee

    5000 micromhos

    Transconductanee . . . . . . . . . . 5000 4500 5100 micromhos

  • Plate Current of

    10 Microamperes

    Plate Current of 10 Microamperes . . . . . —6.8 —7.8 —06.9 volts

  • SCREEN GRID VOLTAGE=

    120 VOLTS

    SCREEN GRID VOLTAGE=120 VOLTS . SCREEN GRID VOLTAGE=120 VOLTS

Other

  • Plate Dissipation

    1.7 watts

    Plate Dissipation . . . . . . . . . . . . . . . . 1.7 watts

  • Sereen Grid Dissipation

    0.5 watt

    Sereen Grid Dissipation . . . . . . . . . . . . . . 0.5 watt