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Tube Tinker — Electron Tube Database
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Specialized - Cathode Ray ·CathodeRay

503HM

Five-inch radar display cathode-ray tube with low-voltage electrostatic focusing, magnetic deflection, and a long-persistence metal-backed screen. Ferranti specifies anode capability to approximately 15 kV.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
B12A
Socket code
-
Base pins
12
Nominal heater
6.3 V / 300 mA

Description

Five-inch radar display cathode-ray tube with low-voltage electrostatic focus, magnetic deflection, and long-persistence metal-backed screen.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
B12A
Socket code
-
Base pins
12
Nominal heater voltage
6.3 V
Nominal heater current
300 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

B12A - 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

Cathode Ray

X-ray radiationInterelectrode capacitances
Max plate voltage
15000 V

Ratings, characteristics, typical operating points, and capacitances were extracted from the supplied Ferranti datasheet.

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

1963 Ferranti

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristic

  • HeaterOrFilamentVoltage

    6.3 V

  • HeaterOrFilamentCurrent

    300 mA

  • FocusingMethod

    LowVoltageElectrostatic

  • DeflectionMethod

    Magnetic

  • Deflection Angle

    53 degree

  • ScreenConstruction

    Metal-backed

  • UsefulScreenDiameterMinimum

    108 mm

  • CathodeToAllCapacitanceMaximum

    8 pF

  • GridToAllCapacitanceMaximum

    8 pF

Other

  • FirstAnodeVoltageMinimum

    200 V

  • FirstAnodeVoltageMaximum

    500 V

  • FinalAnodeVoltageMinimum

    8000 V

  • FinalAnodeVoltageMaximum

    15000 V

  • ThirdAnodeVoltageMaximum

    500 V

    Positive

  • ThirdAnodeVoltageMinimum

    -500 V

    Negative

  • HeaterCathodeVoltageMaximum

    200 V

    HeaterPositive

  • HeaterCathodeVoltageMaximum

    200 V

    HeaterNegative

  • FirstAnodeVoltage

    300 V

  • ThirdAnodeVoltageForFocus

    -300 to +300 V

  • GridVoltageForVisualCutoff

    -30 to -70 V