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

Power - Beam (NOT sweep) ·BeamPower

KT66

Indirectly heated beam pentode designed for high-fidelity audio power-output service, usable in triode or beam-power connection.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
IO
Base pins
8
Nominal heater
6.3 V / 1.27 A

Description

Beam tetrode for low-frequency power amplification in HI-FI audio output stages.

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
1.27 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
22500 Ω
Transconductance
0.005 S
Max plate voltage
550 V
Max screen voltage
550 V
Max plate dissipation
30 W
Max screen dissipation
4.5 W
Max cathode current
200 mA

Promoted values mapped from printed rating/approximate-data tables; additional operating points and capacitances retained as parameters.

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

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

  • Grid1-All Capacitance

    16 pF

  • Anode-All Capacitance

    11.5 pF

  • Anode-Grid1 Capacitance

    1.1 pF

  • Single-Triode Output Power at 250V

    2.2 W

    ClassA;TriodeConnection

  • Single-Triode Output Power at 400V

    5.8 W

    ClassA;TriodeConnection

  • Single-Pentode Output Power

    7.25 W

    ClassA;PentodeConnection

  • Push-Pull Pentode Output Power

    17 W

    ClassAB;PentodeConnection;TwoTubes

  • Push-Pull Pentode Output Power High Voltage

    30 W

    ClassAB;PentodeConnection;TwoTubes

  • Push-Pull Triode Output Power

    14.5 W

    ClassAB;TriodeConnection;TwoTubes

Data set 02

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Characteristic

  • been made

    80 pF

    Published datasheet value; semantic OCR text extraction.

Data set 03

2026 Genalex Rebrand

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Characteristic

  • Plate Current

    60 to 110 mA

    Plate 250 V; screen 250 V; grid -15 V

Other

  • Power Output

    5.4 W

    Plate 250 V; screen 250 V; load 2.2 kohm; ClassA;OneTube

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

    1.3 A

    Published value

  • Ug1

    -200 V

    Published value

Characteristics

  • Ua

    250 V

    Published value

  • Ug2

    250 V

    Published value

  • Ug1

    -15 V

    Published value

  • Ia

    85 mA

    Published value

  • Ig2

    7 mA

    Published value

  • S

    6000 µS

    Published value

  • Ri

    22.5 kΩ

    Published value

  • Ug1

    -15 V

    Published value

  • Ri

    1.3 kΩ

    Published value

Capacitance

  • cg1

    16 pF

    Published value

  • ca

    10 pF

    Published value

  • ca/g1

    2.3 pF

    Published value