Skip to main content
Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Voltage Pentode ·Pentode

403B

Long-life high-transconductance miniature pentode for professional RF and broadband amplification, developed as a durable communications-service replacement.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
E7-1
Socket code
B7G
Base pins
7
Nominal heater
6.3 V / 150 mA

Description

Seven-pin miniature high-transconductance pentode.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
E7-1
Socket code
B7G
Base pins
7
Nominal heater voltage
6.3 V
Nominal heater current
150 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

E7-1 - 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
200 V
Max screen voltage
155 V
Max plate dissipation
1.85 W
Max screen dissipation
0.55 W
Max cathode current
20 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

1956 Western Electric Tubes

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

  • HeaterOrFilamentVoltage

    6.3 V

  • HeaterOrFilamentCurrent

    150 mA

Data set 02

1965 Ericsson Longlife

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Plate supply voltage

    130 V

    ClassA

  • Screen-grid supply voltage

    130 V

    ClassA

  • Cathode bias resistor

    200 Ohm

    ClassA

  • Plate current

    8 mA

    ClassA

  • Screen-grid current

    2 mA

    ClassA

  • Transconductance minimum

    4000 uS

  • Transconductance maximum

    6200 uS

  • Plate current maximum

    10.8 mA

  • Screen-grid current maximum

    2.7 mA

Characteristics

  • Transconductance

    5100 uS

    ClassA

  • Plate resistance

    0.35 MOhm

    ClassA

  • Screen-to-control-grid amplification factor

    28 ratio

    ClassA

  • Equivalent noise resistance

    1600 Ohm

    ClassA

  • Input conductance at 100 MHz

    125 uS

    ClassA

Data set 03

2026 Western Electric 400s

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

  • Heater Voltage . . _ . . . . . . « v v v v v v v e e

    6.3 volts

    Heater Voltage . . _ . . . . . . « v v v v v v v e e 6.3 volts

  • Plate Current E, = E;,

    5 volts

    Plate Current E, = E;,5 = 120 volts; .« . . 7.5 milliamperes

  • Transconductance Cathode Bias Resistor =

    200 ohms

    Transconductance Cathode Bias Resistor = 200 ohms 5000 micromhos

  • Heater Current. . . . e

    150 milliamperes

    Heater Current. . . . e 150 milliamperes

  • Plate voltage

    200 volts

    Plate voltage . . 200 volts

  • Screen Grid Voltage

    155 volts

    Screen Grid Voltage 155 volts

  • Cathode Current

    20 milliamperes

    Cathode Current . 20 milliamperes

  • Heater Cathode Voltage

    130 volts

    Heater Cathode Voltage 130 volts

  • Bulb Temperature

    130 centigrade

    Bulb Temperature. 130 centigrade

  • For Fixed Bias

    1 megohm

    For Fixed Bias . 1.0 megohm

  • Plate voltage

    120 volts

    Plate voltage . 120 150 180 volts

  • Screen Grid Voltage

    120 volts

    Screen Grid Voltage 120 140 120 volts

  • Plate Current

    7 milliamperes

    Plate Current . . . 7.0 6.6 7.4 milliamperes-wt—

  • Screen Gird Current

    2.2 milliamperes

    Screen Gird Current- 2.2 2.1 2.1 milliamperes-—--—

  • Plate Resistance

    0.3 megohm

    Plate Resistance. 0.30 0.40 0.45 megohm

  • Transconductance . .o

    5000 micromhos

    Transconductance . .o 5000 4500 5100 micromhos

  • Plate Current of

    10 Microamperes

    Plate Current of 10 Microamperes. -6.8 -7.8 6.9 volts

  • Published value

    14 VOLTS

    14 "SCREEN GRID VOLTAGE =120 VOLTS] g

  • [ SCREEN GRID VOLTAGE =

    120 VOLTS

    [ SCREEN GRID VOLTAGE =120 VOLTS|

Other

  • Plate Dissipation

    1.85 watts

    Plate Dissipation 1.85 watts

  • Screen Grid Dissipation

    0.55 watt

    Screen Grid Dissipation. 0.55 watt