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

20GP4

Twenty-inch direct-view television picture tube with electrostatic focusing and magnetic deflection. Its P4 white screen operates with an anode rating around 14 kV for monochrome receiver display.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
-
Socket code
DUODECAL5
Base pins
12
Nominal heater
6.3 V / 600 mA

Description

Direct-view television picture tube with electrostatic focus, magnetic deflection, P4 white phosphor, and published high-voltage CRT operating data.

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
12
Nominal heater voltage
6.3 V
Nominal heater current
600 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
14000 V
Max screen voltage
500 V

CRT section; Electrostatic focus with magnetic deflection.

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

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Heater voltage

    6.3 V

    Nominal

  • Heater current

    600 mA

    Nominal

  • Grid 2 voltage

    500 V

    Published CRT data

Characteristic

  • Deflection angle

    1 deg

    Published CRT data

Data set 02

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

Characteristic

  • Horizontal deflection angle

    66 deg

    Approximate

  • Diagonal deflection angle

    70 deg

    Approximate

  • Persistence

    Short

  • Faceplate light transmission at center

    66 %

    Approximate

Capacitance

  • Cathode to all other electrodes capacitance

    5 pF

    Approximate

  • Grid #1 to all other electrodes capacitance

    6 pF

    Approximate

Other

  • Heater voltage

    6.3 V

  • Heater current

    600 mA

  • Maximum DC anode voltage

    14000 V

  • Maximum DC grid #2 voltage

    500 V

  • Maximum grid #1 negative bias magnitude

    125 V

  • Maximum grid #1 positive DC bias

    0 V

  • Maximum grid #1 positive peak

    2 V

  • Maximum heater-cathode voltage during warm-up

    410 V

    HeaterNegative;Warmup<=15s

  • Maximum heater-cathode voltage after warm-up

    150 V

    HeaterNegative

  • Maximum heater-cathode voltage heater positive

    150 V

    HeaterPositive

  • Typical DC anode voltage

    14000 V

    TelevisionPictureTube

  • Typical DC grid #2 voltage

    300 V

    TelevisionPictureTube

  • Typical grid #1 visual-extinction range

    -33 to -77 V

    VisualExtinction

  • Ion trap setting

    75 mA

    Approximate

  • Maximum collector/grid #3/grid #5 voltage

    14000 V

  • Maximum grid #4 voltage

    3600 V

  • Typical collector/grid #3/grid #5 voltage

    14000 V

  • Typical grid #4 focusing voltage range

    2750 to 3740 V