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

Power - Beam (NOT sweep) ·BeamPower

KT88

High-power beam tetrode developed for high-fidelity audio output stages, combining approximately 42 W plate dissipation and 800 V plate capability for substantial single-ended or push-pull power.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
IO
Base pins
8
Nominal heater
6.3 V / 1.6 A

Description

Beam tetrode for low-frequency power amplification in HI-FI audio output stages; source co-designates 6550.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
IO
Base pins
8
Nominal heater voltage
6.3 V
Nominal heater current
1.6 A
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

Beam Power

X-ray radiationInterelectrode capacitances
Plate resistance
12000 Ω
Transconductance
0.0115 S
Amplification factor
8
Max plate voltage
800 V
Max screen voltage
600 V
Max plate dissipation
42 W
Max screen dissipation
8 W
Max cathode current
230 mA

Published ratings/characteristics promoted where unambiguous.

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

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

  • and a capacitance of 50—

    150 pF

    Published datasheet value; semantic OCR text extraction.

Characteristic

  • will be obtained with a single inductor and a capacitance of 50—

    150 pF

    Published datasheet value; semantic OCR text extraction.

Data set 02

199X JJ

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

  • Typical Plate Voltage

    250 V

  • Typical Screen Voltage

    250 V

  • TypicalControlGridVoltage

    -15 V

  • Typical Plate Current

    140 mA

  • Typical Screen Current

    7 mA

  • MaximumCombinedPlateScreenDissipation

    46 W

Characteristic

  • GridCapacitance

    16.5 pF

  • Plate Capacitance

    10 pF

  • GridPlateCapacitance

    2.3 pF

Data set 03

199X Svetlana

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Characteristic

  • Voltage (AC or DC) 5.7 6.3

    6.9 V

    SourcePage1-2

  • Current

    1.6 A

    SourcePage1-2

  • base sleeve and heater

    16 pF

    SourcePage1-2

  • base sleeve and heater

    12 pF

    SourcePage1-2

  • Grid no.1 to plate

    1.2 pF

    SourcePage1-2

Other

  • DC plate voltage

    800 V

    SourcePage1-2

  • Grid no.2 DC (screen) voltage

    600 V

    SourcePage1-2

  • Grid no.1 (control) voltage

    -300 V

    SourcePage1-2

  • DC cathode current

    230 mA

    SourcePage1-2

  • Plate dissipation

    42 W

    SourcePage1-2

  • Grid no.2 (screen) dissipation

    8 W

    SourcePage1-2

  • DC plate voltage

    400 V

    TypicalOperation

  • Grid no.2 DC (screen) voltage

    225 V

    TypicalOperation

  • Grid no.1 DC (control) voltage

    -16.5 V

    TypicalOperation

  • Peak AF grid no.1 (control) voltage

    16.5 V

    TypicalOperation

  • Zero-signal plate current

    87 mA

    TypicalOperation

  • Max signal plate current

    105 mA

    TypicalOperation

  • Max signal grid no.2 (screen) current

    18 mA

    TypicalOperation

  • Signal output

    19 W

    TypicalOperation

  • Vscreen =

    300 V

    TypicalOperation

  • Eg =

    0 V

    TypicalOperation

  • Vscreen =

    140 V

    TypicalOperation

Data set 04

2026 JJ Electronic

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

  • Uf

    6.3 V

    Published value

  • If

    1.6 A

    Published value

Characteristics

  • Ua

    250 V

    Published value

  • Ug2

    250 V

    Published value

  • Ia

    140 mA

    Published value

  • Ig2

    7 mA

    Published value

  • Ug1

    -15 V

    Published value

  • S

    11500 µS

    Published value

  • Ri

    12 kΩ

    Published value

  • Ia+g2

    147 mA

    Published value

  • Ug1

    -15 V

    Published value

Capacitance

  • S

    12000 µS

    Published value

  • cg1

    16.5 pF

    Published value

  • Ri

    670 Ω

    Published value

  • µ

    8

    Published value

Data set 05

2026 Tungsol Rebrand

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

  • Power Output

    -

    HI-FI audio power output