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

Power - Triode ·Triode

6A3

Directly heated low-mu audio power triode for final output stages in AC receivers and amplifiers. Approximately 15 W plate dissipation and high transconductance support several watts of single-ended Class A output as well as push-pull audio service.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
4D
Socket code
UX4
Base pins
4
Nominal heater
6.3 V / 1 A

Description

Power triode intended for the final stage of AC receivers or amplifiers, providing substantial Class-A output and usable in push-pull operation.

Socket description

Medium-shell UX 4-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
4D
Socket code
UX4
Base pins
4
Nominal heater voltage
6.3 V
Nominal heater current
1 A
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

4D - 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

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
800 Ω
Transconductance
0.00525 S
Amplification factor
4.2
Max plate voltage
325 V
Max plate dissipation
15 W
Max cathode current
100 mA

Published promoted fields populated from the datasheet; identical repeated sections compressed where applicable.

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

1937 Raytheon Radio Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Capacitance

  • Grid-to-plate capacitance

    16 pF

    Section1

  • Input capacitance

    7 pF

    Section1

  • Output capacitance

    5 pF

    Section1

Other

  • Plate voltage

    250 V

    ClassA

  • Control-grid voltage

    -45 V

    ClassA

  • Plate current

    60 mA

    ClassA

  • Load resistance

    2500 Ω

    ClassA

  • Power output

    3.2 W

    ClassA

  • Plate voltage

    325 V

    ClassAB;PushPull;TwoTubes

  • Control-grid voltage

    -68 V

    ClassAB;PushPull;TwoTubes

  • Load resistance plate-to-plate

    3000 Ω

    ClassAB;PushPull;TwoTubes;FixedBias

  • Power output

    15 W

    ClassAB;PushPull;TwoTubes;FixedBias

Characteristic

  • Plate resistance

    800 Ω

    Section1

  • Transconductance

    5250 µS

    Section1

  • Amplification factor

    4.2

    Section1

Data set 02

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Anode Voltage

    250 V

    ClassA

  • Anode Current

    60 mA

    ClassA

  • Control Grid Voltage

    -45 V

    ClassA

  • Cathode Bias Resistor

    750 ohm

    ClassA

  • Optimum Load

    2500 ohm

    ClassA

  • Power Output

    3.5 W

    ClassA

  • Anode Voltage

    325 V

    ClassAB; TwoTubes

  • Anode Current

    60 mA

    ClassAB; TwoTubes

  • Control Grid Voltage

    -68 V

    ClassAB; TwoTubes

  • Cathode Bias Resistor

    850 ohm

    ClassAB; TwoTubes

  • Optimum Load

    5000 ohm

    ClassAB; TwoTubes

  • Power Output

    10 W

    ClassAB; TwoTubes

Data set 03

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

  • Plate Resistance

    800 ohm

  • Transconductance

    5250 µS

  • Amplification Factor

    4.2

Other

  • Maximum Plate Voltage

    325 V

  • Class A Plate Voltage

    250 V

  • Class A Plate Current

    60 mA

  • Class A Load Resistance

    2500 ohm

  • Class A Power Output

    3.2 W

Data set 04

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Maximum plate voltage

    325 V

    Published handbook rating

  • Plate voltage

    250 V

    ClassA

  • Control-grid bias

    45 V

    ClassA

  • Plate current

    60 mA

    ClassA

  • Load resistance

    2500 ohm

    ClassA

  • Power output

    3.2 W

    ClassA

Characteristic

  • Plate resistance

    800 ohm

    Published handbook characteristic

  • Transconductance

    5250 µS

    Published handbook characteristic

  • Amplification factor

    4.2

    Published handbook characteristic

  • Heater/filament voltage

    6.3 V

    Published heater/filament rating

  • Heater/filament current

    1 A

    Published heater/filament rating

Data set 05

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Power Output

    3.5 W

    ClassA1

  • Total Harmonic Distortion

    5 %

    ClassA1

Data set 06

2026 Sovtek

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Current

    60 mA

    Plate 250 V; ClassA;OneTube

  • Power Output

    3 W

    Plate 250 V; Load 2.5 kohm; ClassA;OneTube