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Rectifier - Half Wave ·Rectifier

249A

Directly heated mercury-vapor half-wave rectifier; 2.5 V, 7 A filament; 6.5 kV peak inverse voltage; 1.1 A peak current.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
UX4
Base pins
4
Nominal heater
2.5 V / 7 A

Description

Western Electric 249A is a directly heated, half-wave mercury-vapor rectifier with an oxide-coated filamentary cathode, 2.5 V AC / 7 A filament, 6,500 V maximum peak inverse potential and 1.1 A maximum peak plate current. Approximate conducting anode-cathode drop is 15 V (5–25 V variation). Four-prong base with parallel-connected filament terminals and a separate top anode connection; operate vertically, base down.

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
4
Nominal heater voltage
2.5 V
Nominal heater current
7 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

Rectifier

X-ray radiationInterelectrode capacitances
Rectifier peak inverse voltage
6500 V
Rectifier nominal output current
400 mA
Rectifier peak forward current
1.1 A
Rectifier forward voltage drop
15 V

Western Electric 249A mercury-vapor half-wave rectifier. 0.4 A is the specified load current for a single-phase half-wave circuit at 2,000 V; not an unrestricted maximum. Conducting voltage drop 5–25 V, approximately 15 V nominal. Safe ambient 0–50 °C. Other published multi-tube circuits: 2 tubes 2,000 V/0.8 A; 4 tubes 4,000 V/0.8 A; 6 tubes 6,000 V/1.0 A.

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

1933 Western Electric Tubes

Published operating points and test conditions from this source.

SECTION 1

Rectifier

Characteristic

  • Anode-cathode conducting drop

    5 to 25 V

    Approximate conducting anode-cathode potential drop 15 V; varies 5–25 V.

  • Ambient Temperature

    0 to 50 °C

    Safe operating ambient temperature

  • Load Potential

    2000 V

    Single-phase half-wave; 1 tube; load current 0.4 A

  • Load Current

    400 mA

    Single-phase half-wave; 1 tube; load potential 2000 V

  • Load Current

    800 mA

    Single-phase double half-wave; 2 tubes; load potential 2000 V

  • Load Current

    800 mA

    Single-phase double half-wave, four-tube series circuit; load potential 4000 V

  • Load Current

    1 A

    Three-phase six-tube series Y circuit; load potential 6000 V

Data set 02

2026 Western Electric 200s

Published operating points and test conditions from this source.

SECTION 1

Rectifier

Characteristic

  • Filament Voltage

    2.5 Volt

    Filament Voltage 2.5 Volts, AC

  • Nominal Filament Current

    7 Amperes

    Nominal Filament Current 7.0 Amperes

  • Forward Voltage Drop

    5 to 25 V

    Conducting anode-cathode voltage drop: approximately 15 V; varies 5–25 V with ambient temperature and plate current.

Other

  • Maximmn Peak Plate Current

    1.1 Amperes

    Maximmn Peak Plate Current 1.1 Amperes

  • Maximum Peak Inverse Potential

    6500 Volts

    Maximum Peak Inverse Potential 6,500 Volts