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Power - Triode ·Triode

2A3EH

Modern directly heated 2A3-family audio power triode for Class A output service. Published operation around 250 V provides roughly 3 W single-ended output, retaining the low-mu behavior and modest plate resistance characteristic of the 2A3 family.

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

Description

Directly heated power triode for low-frequency power amplification.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
Base pins
-
Nominal heater voltage
2.5 V
Nominal heater current
2.5 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

Triode

X-ray radiationInterelectrode capacitances
Transconductance
0.0038 S
Amplification factor
4.1
Max plate voltage
360 V
Max plate dissipation
17.5 W
Max cathode current
100 mA

Published ratings and characteristics promoted from the approved source.

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 Electro Harmonix Gold

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Plate Current

    40 to 80 mA

    Plate 250 V; Grid -44 V

  • Power Output

    3 W

    Plate 250 V; Load 2.5 kohm; ClassA;OneTube

  • Negative Grid Voltage Maximum

    150 V