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

20CP4

Twenty-inch direct-view television picture tube with magnetic focusing, magnetic deflection, and a P4 white screen. Published high-voltage operating data reach about 18 kV for bright monochrome receiver display.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
12D
Socket code
DUODECAL5
Base pins
5
Nominal heater
6.3 V / 600 mA

Description

Direct-view television picture tube with magnetic 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
12D
Socket code
DUODECAL5
Base pins
5
Nominal heater voltage
6.3 V
Nominal heater current
600 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

12D - 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
410 V

CRT section; Magnetic 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 current

    600 mA

    Nominal

  • Anode voltage

    18 V

    Published CRT data

  • Grid 2 voltage

    410 V

    Published CRT data

Characteristic

  • Deflection angle

    66 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

    Magnetic

  • Deflecting method

    Magnetic

  • Phosphor

    P4

    White

Characteristic

  • Horizontal deflection angle

    66 deg

    Approximate

  • Diagonal deflection angle

    70 deg

    Approximate

  • Persistence

    Medium

  • 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

    410 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

    12000 V

    TelevisionPictureTube

  • Typical DC grid #2 voltage

    300 V

    TelevisionPictureTube

  • Typical grid #1 visual-extinction range

    -33 to -77 V

    VisualExtinction

  • Focusing coil current

    95 mA

    Approximate

  • Ion trap setting

    50 mA

    Approximate

Data set 03

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Typical Anode Voltage

    16000 V

  • Typical Grid No. 2 Voltage

    300 V

  • Grid No. 1 Maximum Negative Bias

    125 V

  • Grid No. 1 Maximum Positive Peak

    2 V