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Power - Triode ·Triode

45B

Power triode documented for amplifier or control service, with manufacturer operating data emphasizing useful power output rather than small-signal voltage amplification. Its available documentation does not justify a narrower specialized functional category.

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

Description

Higher-power directly heated 45-family 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.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
UX4
Socket code
-
Base pins
-
Nominal heater voltage
2.5 V
Nominal heater current
1.5 A
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

UX4 - 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
1670 Ω
Transconductance
0.0021 S
Amplification factor
3.5
Max plate voltage
420 V
Max plate dissipation
22 W
Max cathode current
53 mA

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

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

    1670 ohm

    ClassA

  • Amplification factor

    3.5

    ClassA

  • Transconductance

    2100 uS

    ClassA

Other

  • Plate voltage

    275 V

    ClassA

  • Plate current

    36 mA

    ClassA

  • Grid voltage

    -56 V

    ClassA

  • Load resistance

    4600 ohm

    ClassA

  • Output power

    2 W

    ClassA

Capacitance

  • Grid-plate capacitance

    7 pF

  • Grid-filament capacitance

    4 pF

  • Plate-filament capacitance

    3 pF