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

21GKP4

Twenty-one-inch 114-degree monochrome television picture tube with electrostatic focus, magnetic deflection, and an aluminized P4 screen. Designed for high-voltage direct-view receiver service, it combines wide-angle scanning with a bright white display.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
-
Socket code
DUODECAL5
Base pins
-
Nominal heater
6.3 V / 450 mA

Description

21-inch 114-degree monochrome television CRT with electrostatic focus, magnetic deflection, and aluminized P4 screen.

Socket description

Small-shell Duodecal 5-contact CRT base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
DUODECAL5
Base pins
-
Nominal heater voltage
6.3 V
Nominal heater current
450 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
22000 V

Published Westinghouse ratings, characteristics, CRT EHT/focus/deflection values, capacitances, and pulse data promoted where applicable; additional values retained as parameters.

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

1965 Sylvania Electronic Tubes Vol3

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Characteristics

  • Focusing method

    Electrostatic

  • Deflection method

    Magnetic

  • Heater voltage

    6.3 V

  • Heater current

    450 mA

  • Diagonal deflection angle

    114 deg

  • Heater warm-up time

    11 s

Construction

  • Phosphor

    Aluminized P4

Other

  • Maximum anode voltage

    22000 V

  • Grid1 circuit resistance maximum

    1.5 Mohm

  • Anode voltage minimum

    12000 V

  • Typical anode voltage

    18000 V

  • Typical focus-electrode voltage

    0 to 400 V

  • Typical grid2 voltage

    500 V

  • Focus-electrode voltage minimum

    -550 V

  • Focus-electrode voltage maximum

    1100 V

  • Heater-cathode voltage maximum

    200 V

Application

  • Application

    Monochrome television picture display

Capacitance

  • Cathode-to-all capacitance

    5 pF

  • Grid1-to-all capacitance

    6 pF