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Power - Triode ·Triode-Triode

5998

Medium/low-mu twin power triode designed primarily as a series-pass tube in regulated power supplies. Its low plate resistance and high transconductance provide substantial current at comparatively small tube voltage drop.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
B8-11
Socket code
IO
Base pins
8
Nominal heater
6.3 V / 2.4 A

Description

The 5998 is a medium/low-mu twin power triode intended primarily as a series pass tube in regulated power supplies, providing high current at low tube voltage drop.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
B8-11
Socket code
IO
Base pins
8
Nominal heater voltage
6.3 V
Nominal heater current
2.4 A
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

B8-11 - Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
350 Ω
Transconductance
0.014 S
Amplification factor
5.5
Max plate voltage
275 V
Max plate dissipation
15 W
Max cathode current
140 mA
Rectifier max heater-cathode voltage
200 V

Representative row for two electrically identical triode sections; maximum ratings apply to each triode.

Section 2

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
350 Ω
Transconductance
0.014 S
Amplification factor
5.5
Max plate voltage
275 V
Max plate dissipation
15 W
Max cathode current
140 mA
Rectifier max heater-cathode voltage
200 V

Second physical triode section; identical dual-triode structure per reviewed datasheets.

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

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Voltage

    110 V

    ClassA;EachUnit

  • Cathode Resistor

    105 ohm

    ClassA;EachUnit

  • Plate Current

    100 mA

    ClassA;EachUnit

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Service

    Series regulator

    DCPowerSupply

Data set 03

1966 Tung Sol Electronic Tubes 4 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

  • Grid-to-cathode capacitance each section

    7.7 pF

    WholeTube

  • Grid-to-plate capacitance each section

    18.3 pF

    WholeTube

  • Cathode-to-plate capacitance each section

    2.5 pF

    WholeTube

  • Heater-to-cathode capacitance each section

    10 pF

    WholeTube

  • Plate-to-plate capacitance between sections

    1.7 pF

    WholeTube

  • Minimum cathode heating time

    30 s

    WholeTube

  • Transconductance per section

    14000 uS

    WholeTube

  • Amplification factor

    5.5

    WholeTube

Other

  • Maximum plate voltage

    275 V

    WholeTube

  • Maximum plate dissipation per plate

    15 W

    WholeTube

  • Maximum DC plate current per plate

    140 mA

    WholeTube

Data set 04

2026 Western Electric 400s

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Maximum heater-cathode voltage

    150 V

    EachTriode

  • Maximum grid circuit resistance, cathode bias

    0.1 Mohm

    EachTriode

Characteristic

  • Plate current at representative condition

    125 mA

    PlateSupplyVoltage=110V

Data set 05

2026 Western Electric Other

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Heater Voltage

    6.3 V

    General characteristics

  • Heater Current

    2.4 A

    General characteristics

  • Plate Voltage Maximum

    250 V

    Each triode; design-center value

  • Plate Dissipation Maximum

    13 W

    Each triode; design-center value

  • Cathode Current Maximum

    125 mA

    Each triode; design-center value

  • Heater-Cathode Voltage Maximum

    150 V

    Each triode; design-center value

  • Bulb Temperature Maximum

    200 degC

    Design-center value

  • Grid Circuit Resistance Maximum

    0.1 megohm

    Cathode bias

  • Plate Supply Voltage

    110 V

    Each triode; operating column 1

  • Cathode Bias Resistance

    90 ohm

    Each triode; operating column 1

  • Plate Supply Voltage

    110 V

    Each triode; operating column 2

  • Cathode Bias Resistance

    65 ohm

    Each triode; operating column 2

Characteristic

  • Plate Current

    100 mA

    Each triode; operating column 1

  • Amplification Factor

    5.9

    Each triode; operating column 1

  • Plate Resistance

    330 ohm

    Each triode; operating column 1

  • Transconductance

    18000 uS

    Each triode; operating column 1

  • Plate Current

    125 mA

    Each triode; operating column 2

  • Amplification Factor

    6.1

    Each triode; operating column 2

  • Plate Resistance

    305 ohm

    Each triode; operating column 2

  • Transconductance

    20000 uS

    Each triode; operating column 2

Application

  • Recommended Heater-Cathode Voltage for Optimum Life

    90 V

    Should not exceed for optimum life expectancy

  • Recommended Bulb Temperature for Optimum Life

    150 degC

    Forced-air cooling should keep bulb below this temperature