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Specialized - Cathode Ray ·CathodeRay

21FP4C

Twenty-one-inch direct-view monochrome television picture tube with magnetic deflection and high-voltage operation. Manufacturer documentation describes its focusing system, picture-screen construction, and receiver-display characteristics for large-screen television service.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
12L
Socket code
DUODECAL6
Base pins
12
Nominal heater
6.3 V / 600 mA

Description

Aluminized-screen 21FP4-family rectangular picture tube with electrostatic focus, magnetic deflection, grey-filter faceplate, and conductive coating.

Socket description

Small-shell Duodecal 6-contact CRT base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
12L
Socket code
DUODECAL6
Base pins
12
Nominal heater voltage
6.3 V
Nominal heater current
600 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

12L - 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
18000 V
Max screen voltage
500 V
Rectifier max heater-cathode voltage
180 V

Maximum anode voltage mapped to MaxPlateVoltage; CRT grid/focusing limits retained as parameters rather than mis-promoted as ordinary screen-grid data.

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

1956 National Video

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Typical Anode Voltage

    13600 V

  • Phosphor

    P4

Characteristic

  • Heater Voltage Nominal

    6.3 V

  • Heater Current Nominal

    600 mA

Capacitance

  • Cathode to All Other Electrodes Capacitance

    5 pF

    Approximate

  • Grid 1 to All Other Electrodes Capacitance

    6 pF

    Approximate

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • HighVoltageAnodeMaximum

    20000 V

    CRT

Capacitance

  • CathodeToOtherElectrodesCapacitance

    5 pF

    Approximate

Data set 03

1966 Tung Sol Electronic Tubes 4 of 4

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Construction

  • Focusing method

    Electrostatic

  • Deflecting method

    Magnetic

  • Phosphor

    P4

    White;MediumPersistence

  • External conductive coating

    Present

  • Aluminized screen

    Present

Characteristic

  • Deflection angle

    70 deg

    Approximate

  • Faceplate light transmission at center

    66 %

    Approximate

Other

  • Heater voltage

    6.3 V

  • Heater current

    600 mA

  • Maximum DC anode voltage

    18000 V

  • Maximum DC grid #2 voltage

    500 V

  • Maximum grid #1 negative-bias magnitude

    125 V

  • Maximum grid #1 positive DC voltage

    0 V

  • Maximum grid #1 positive peak voltage

    2 V

  • Typical DC anode voltage

    14000 V

    TelevisionPictureTube

  • Typical DC grid #2 voltage

    300 V

    TelevisionPictureTube

  • Typical grid #1 voltage minimum

    -77 V

    VisualExtinctionRange

  • Typical grid #1 voltage maximum

    -33 V

    VisualExtinctionRange

  • Maximum grid #1 circuit resistance

    1.5 megohm

  • Ion trap magnet rated strength

    35 gauss

    Approximate

  • Focusing electrode voltage minimum

    -570 V

    ElectrostaticFocus

  • Focusing electrode voltage maximum

    330 V

    ElectrostaticFocus

  • Maximum focusing electrode voltage minimum

    -500 V

    ElectrostaticFocus

  • Maximum focusing electrode voltage maximum

    1000 V

    ElectrostaticFocus

  • X-ray shielding warning

    Present

    HighAnodeVoltage

Capacitance

  • Cathode-to-all-other-electrodes capacitance

    5 pF

    Approximate

  • Grid #1-to-all-other-electrodes capacitance

    6 pF

    Approximate

Application

  • Application

    Direct-view television picture tube

Data set 04

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Maximum Anode Voltage

    18000 V

  • Maximum Grid No. 2 Voltage

    500 V

  • Anode Voltage

    16000 V

    Typical

  • Heater Voltage

    6.3 V

  • Heater Current

    600 mA