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Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Specialized - Cathode Ray ·CathodeRay

21DMP4

Twenty-one-inch lightweight direct-view television picture tube with electrostatic focusing and 110-degree magnetic deflection. National Video publishes high-voltage operation around 20 kV together with an explicit X-ray warning.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized
Sections
1
Base
8HR
Socket code
NEOEIGHTAR7
Base pins
8
Nominal heater
6.3 V / 600 mA

Description

21-inch electrostatic-focus, 110-degree magnetic-deflection lightweight picture tube; X-ray warning published.

Socket description

Small-button Neoeightar 7-contact CRT base family

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
8HR
Socket code
NEOEIGHTAR7
Base pins
8
Nominal heater voltage
6.3 V
Nominal heater current
600 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

8HR - 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
20000 V
Max screen voltage
500 V
Rectifier max heater-cathode voltage
180 V

CRT anode and grid-2 maximum ratings are promoted from the printed ratings block; other CRT-specific focus/drive/deflection values are preserved in 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

1956 National Video

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Typical Anode Voltage

    16000 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