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Specialized - Cathode Ray ·CathodeRay

21EMP4

Twenty-one-inch direct-view monochrome television picture tube with magnetic deflection and a P4 display screen. Manufacturer documentation places it in the high-voltage receiver CRT family, with construction optimized for bright rectangular picture presentation.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
-
Socket code
B7G
Base pins
-
Nominal heater
6.3 V / 300 mA

Description

The Westinghouse 21EMP4 is a 21-inch 110-degree aluminized P4 CRT with short neck and no ion trap.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
B7G
Base pins
-
Nominal heater voltage
6.3 V
Nominal heater current
300 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
18000 V

Published electrical limits promoted from the source. Passive microwave reference cavities have their electrical frequency/Q values in TUBE_SECTION_PARAMETER because no applicable promoted frequency field exists in the fixed section schema.

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

1947 Westinghouse

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • HeaterVoltageNominal

    6.3 V

    Nominal

  • HeaterCurrentNominal

    300 mA

    Nominal

  • MaximumElectrodeOrAnodeVoltage

    18000 V

  • Grid2VoltageMaximum

    500 V

Data set 02

1965 Westinghouse Data Book

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

  • Heater Voltage

    6.3 V

  • Heater Current

    600 mA

  • Heater Warm-up Time

    11 s

  • Focusing Method

    Low Voltage Electrostatic text

  • Deflection Method

    Magnetic text

  • Horizontal Deflection Angle

    105 deg

    Approximate

  • Vertical Deflection Angle

    87 deg

    Approximate

  • Diagonal Deflection Angle

    110 deg

    Approximate

  • Phosphor

    Aluminized P4 text

  • Fluorescence

    White text

  • Persistence

    Short to Medium text

  • Light Transmittance

    73 percent

    Approximate

  • Cathode-to-All Capacitance

    5 pF

    Approximate

  • Grid1-to-All Capacitance

    6 pF

    Approximate

  • External Coating-to-Anode Capacitance Minimum

    2000 pF

  • External Coating-to-Anode Capacitance Maximum

    2500 pF

Other

  • Maximum Anode Voltage

    18000 V

  • Minimum Anode Voltage

    11000 V

  • Maximum Focus Electrode Voltage Positive

    1100 V

    Grid4

  • Maximum Focus Electrode Voltage Negative

    -550 V

    Grid4

  • Maximum Grid2 Voltage

    500 V

  • Minimum Grid2 Voltage

    200 V

  • Maximum Heater-Cathode Voltage During Warmup

    450 V

    Duration<=15s

  • Maximum Heater-Cathode Voltage After Warmup

    180 V

  • Typical Anode Voltage

    16000 V

    CathodeDrive

  • Typical Focus Voltage Minimum

    0 V

    Grid4

  • Typical Focus Voltage Maximum

    400 V

    Grid4

  • Typical Grid2 Voltage

    450 V

    CathodeDrive

  • Cathode Voltage for Raster Cutoff Minimum

    45 V

    CathodeDrive

  • Cathode Voltage for Raster Cutoff Maximum

    105 V

    CathodeDrive

  • Maximum Grid1 Circuit Resistance

    1.5 Mohm