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Power - Triode ·Triode

45

Classic directly heated low-mu audio output triode for battery-era and early AC receivers. Manufacturer operating data emphasize Class A power output at modest plate voltage, making it a receiving-set output device rather than a transmitting tube.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
4D
Socket code
UX4
Base pins
4
Nominal heater
2.5 V / 1.5 A

Description

Directly heated Type 45 audio output triode. The supplied Emission Labs sheet was read for filament data, maximum ratings, representative operating points, gm/rp/mu, output conditions, capacitances, and rectifier filter conditions as applicable.

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
2.5 V
Nominal heater current
1.5 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
1650 Ω
Transconductance
0.002125 S
Amplification factor
3.5
Max plate voltage
275 V
Max plate dissipation
10 W
Max cathode current
36 mA

Published promoted fields populated by semantic headings; identical repeated sections compressed.

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

1932 Cunningham Radio Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Grid-plate capacitance

    8 pF

    Published direct interelectrode capacitance

  • Grid-filament capacitance

    5 pF

    Published direct interelectrode capacitance

  • Plate-filament capacitance

    3 pF

    Published direct interelectrode capacitance

  • Undistorted power output

    2000 mW

    Published operating characteristic

  • Load resistance

    3500 ohm

    Published operating characteristic

Data set 02

1937 Raytheon Radio Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Voltage

    275 V

    ClassA

  • Grid Voltage

    -56 V

    ClassA

  • Plate Current

    36 mA

    ClassA

  • Load Resistance

    4600 ohm

    ClassA

  • Power Output

    2 W

    ClassA

Data set 03

193X Cunningham

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Heater/filament voltage

    2.5 V

    Published nominal

  • Heater/filament current

    1.5 A

    Published nominal

  • Transconductance

    2000 uS

    Published characteristic

  • Amplification factor

    3.5

    Published characteristic

  • Plate resistance

    1750 Ohm

    Published characteristic

Data set 04

1940 RCA

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • HeaterVoltageNominal

    2.5 V

    Nominal

  • HeaterCurrentNominal

    1.5 A

    Nominal

  • Maximum Plate Voltage

    275 V

  • Maximum Cathode Current

    36 mA

Characteristic

  • Transconductance

    2050 µS

    Typical

  • Amplification Factor

    3.5

    Typical

  • Plate Resistance

    1700 ohm

    Typical

Data set 05

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Voltage

    250 V

  • Plate Current

    36 mA

  • Grid Voltage

    -50 V

  • Optimum Load

    3900 ohm

  • Power Output

    1.6 W

Characteristic

  • Plate Resistance

    1600 ohm

  • Transconductance

    2200 µS

  • Amplification Factor

    3.5

Data set 06

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Voltage

    275 V

    ClassA

  • Grid Voltage

    -56 V

    ClassA

  • Plate Current

    36 mA

    ClassA

  • Load Resistance

    4600 ohm

    ClassA

  • Power Output

    2 W

    ClassA

Data set 07

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

  • Plate Resistance

    1650 ohm

    Typical

  • Transconductance

    2125 uS

    Typical

  • Amplification Factor

    3.5

    Typical

Other

  • Power Output

    18 W

    PushPull

Data set 08

2026 Emission Labs

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Filament voltage

    2.5 V

  • Filament current

    1.5 A

  • Plate resistance

    1750 ohm

    ClassA

  • Amplification factor

    3.5

    ClassA

  • Transconductance

    2000 uS

    ClassA

Other

  • Plate voltage

    250 V

    ClassA

  • Plate current

    34 mA

    ClassA

  • Grid voltage

    -50 V

    ClassA

  • Load resistance

    3900 ohm

    ClassA

  • Output power

    1.6 W

    ClassA

  • Maximum Class A output power

    2.5 W