425A

Four-electrode inert-gas-filled cold-cathode relay tube with isolated starter and main discharge gaps, providing electrical isolation between control and switched portions of a circuit.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized

Sections: 1
Base: -
Socket code: UX4
Base pins: -
Nominal heater: -

Description

Western Electric 425A is a Four-electrode inert-gas-filled cold-cathode relay tube with isolated starter and main gaps.

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: -
Socket code: UX4
Base pins: -
Nominal heater voltage: -
Nominal heater current: -
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

RelayControlSwitch

X-ray radiationInterelectrode capacitances

Max cathode current: 50 mA
Regulator starting voltage: 80 V
Regulator maintaining voltage: 75 V

Special cold-cathode relay/control section; current and starter/anode voltage data promoted where semantically applicable.

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 400s

Published operating points and test conditions from this source.

SECTION 1

RelayControlSwitch

Other

Forward peak anode voltage
180 V
Maximum average cathode current
20 mA

Characteristic

Starter breakdown voltage
80 V
Anode voltage drop
75 V