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Specialized - Thyratron ·Thyratron

394A

Gas-filled grid-controlled thyratron for switching, controlled-rectifier, relay, motor-control, oscillator, or pulse service as documented by the manufacturer.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
-
Socket code
UX4
Base pins
-
Nominal heater
2.5 V / 3.25 A

Description

The 394A is a three-electrode mercury-vapor and gas-filled thyratron with a negative control characteristic, designed for use in regulated or controlled rectifiers.

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
2.5 V
Nominal heater current
3.25 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

Thyratron

X-ray radiationInterelectrode capacitances
Max plate voltage
1250 V
Max cathode current
640 mA

Three-electrode thyratron; SectionType=Other because Thyratron is not a canonical SectionType. MaxPlateVoltage uses published peak anode voltage; MaxCathodeCurrent uses maximum average cathode current.

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

Thyratron

Other

  • Peak Cathode Current

    2.5 A

  • CathodeSurgeCurrent

    25 A

    Maximum duration 0.1 s

  • NegativeGridVoltageBeforeConduction

    500 V

  • NegativeGridVoltageDuringConduction

    10 V

  • PositiveGridCurrentAverage

    10 mA

    Averaging time one cycle

  • Anode Grid Capacitance

    1.6 pF

    Bogey

  • GridFilamentCapacitance

    5.5 pF

    Bogey

  • CondensedMercuryTemperature

    -55 to 80 degC

Characteristic

  • Anode Voltage Drop

    15 V

    Bogey

  • RequiredFilamentHeatingTime

    15 s