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

4050BD

Early electrostatic cathode-ray oscillograph tube with a long-afterglow screen, intended for measurement display; manufacturer data specifies deflection sensitivity and operation over roughly 300–2000 V anode supply.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
-
Socket code
BRITISH9
Base pins
9
Nominal heater
0.75 V / 900 mA

Description

Gas-filled cathode-ray tube with electrostatic deflection, a directly heated filament, 300-2000 V anode range, and a long afterglow of 10-15 seconds in the dark.

Socket description

Standard British 9-contact base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
BRITISH9
Base pins
9
Nominal heater voltage
0.75 V
Nominal heater current
900 mA
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

Cathode Ray

X-ray radiationInterelectrode capacitances
Max plate voltage
1500 V

Gas-focused CRT; delay screen.

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

1937 Standard Valves

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

  • Filament current range

    700 mA to 1.1 A

  • Anode voltage range

    300 to 2000 V

  • Normal anode voltage

    350 V

  • Deflecting-plate pair capacitance

    5.5 pF

    Including socket

  • Single deflecting plate to anode capacitance

    7.8 pF

    Including socket

  • Deflecting-plate pair conductance

    1 umho

    Approximate

  • Shield voltage range

    0 to 50 V

    From potentiometer

  • Sensitivity

    440 mm/V

    Approximate

  • Screen characteristic

    long afterglow of 10-15 seconds in the dark

Data set 02

1946 Standard Telephone and Cables

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

  • Interelectrode capacitances published

    1

    See source table for individual capacitances

Data set 03

1947 Standard Valves

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Filament current

    700 mA to 1.1 A

  • Anode voltage

    350 to 1500 V

  • Normal anode voltage

    500 V

  • Shield voltage

    0 to 50 V

Characteristics

  • Sensitivity

    580 mm/V

    V = anode voltage

Dimensions

  • Effective screen diameter

    6.5 in