311A

Power pentode designed for both audio/output amplification and radio-frequency power-amplifier service.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: UX5
Base pins: 5
Nominal heater: 10 V / 640 mA

Description

Western Electric 311A is a low-power indirectly heated suppressor-grid pentode for audio, carrier or radio-frequency power amplification; the 311A and 329A differ only in heater rating.

Socket description

Small 5-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: UX5
Base pins: 5
Nominal heater voltage: 10 V
Nominal heater current: 640 mA
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

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 50000 Ω
Transconductance: 0.0029 S
Amplification factor: 146
Max plate voltage: 180 V
Max screen voltage: 150 V
Max plate dissipation: 9 W
Max screen dissipation: 1.8 W
Max cathode current: 60 mA

Promoted fields audited from printed ratings/characteristics; remaining published values preserved 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

2026 Western Electric 300s

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

Control grid to plate
0.29 pF
Control grid to heater/cathode/screen grid
8 pF
Plate to heater/cathode/screen grid
9 pF

Other

Maximum direct screen-grid current
12 mA

Characteristic

Typical plate current
31 mA
PlateVoltage=180V;ScreenGridVoltage=135V;ControlGridVoltage=-15V