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Tube Tinker — Electron Tube Database
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Voltage - Triode (single) ·Triode

30A

High-gain directly heated triode for driver and preamplifier service in audio and general electronic equipment.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
UX4
Socket code
UX4
Base pins
4
Nominal heater
5 V / 1.4 A

Description

High-gain directly heated driver/pre-amplifier 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
UX4
Socket code
UX4
Base pins
4
Nominal heater voltage
5 V
Nominal heater current
1.4 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
6200 Ω
Transconductance
0.0052 S
Amplification factor
32
Max plate voltage
500 V
Max plate dissipation
11 W
Max cathode current
40 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

    5 V

  • Filament current

    1.4 A

  • Factory test plate voltage

    400 V

  • Factory test plate current

    25 mA

  • Factory test grid voltage

    -8.1 V

  • Plate resistance

    6200 ohm

  • Amplification factor

    32

  • Transconductance

    5200 uS

  • Unloaded amplification factor

    32