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Specialized - Cathode Ray ·CathodeRay

19ENP4A

Wide-angle aluminized P4 monochrome television picture tube using electrostatic focusing and magnetic deflection, designed for high-voltage direct-view service with a large approximately 19-inch screen.

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

Description

19ENP4A — Cathode-Drive Picture Tube

The 19ENP4A is a cathode-drive television picture tube designed with integral PAN-O-PLY implosion protection. It features low-voltage electrostatic focusing, 114-degree magnetic deflection, and an electron gun that operates without requiring an external ion-trap magnet.

Optical and Mechanical Design

The 19ENP4A utilizes an aluminized, sulfide-type P4 phosphor screen. The faceplate is constructed of filterglass, providing approximately 48% light transmission at the center to enhance picture contrast.

Mechanically, the tube weighs approximately 15 pounds. Its physical dimensions and envelope features include:

  • Overall Length: 11.625 ± 0.250 inches
  • Neck Length: 4.375 ± 0.125 inches
  • Projected Screen Area: 172 square inches
  • External Conductive Coating: Modified-Band type, with a grounding contact area located near the Reference Line.
  • Anode Cap: Recessed Small Cavity (JEDEC No. J1-21)
  • Base: Small-Button Neoeightar 7-Pin, Arrangement 1 (JEDEC No. B7-208)

To ensure safe and stable operation, both the external conductive coating and the integral implosion protection hardware must be connected to a reliable system ground.

Terminal Connections and Pinout

The 19ENP4A uses a 7-pin Small-Button Neoeightar base (JEDEC No. B7-208) with an 8HR bottom-view pin arrangement. The electrical connections are distributed as follows:

TerminalConnection
Pin 1Heater
Pin 2Grid No. 1
Pin 3Grid No. 2
Pin 4Grid No. 4 (Focusing Electrode)
Pin 6Grid No. 1
Pin 7Cathode
Pin 8Heater
CapAnode (Grid No. 3, Grid No. 5, Screen, Collector)
Coating (C)External Conductive Coating

Grid No. 1 is internally connected to both Pin 2 and Pin 6. The high-voltage anode connection is made via the recessed small cavity cap, which ties together Grid No. 3, Grid No. 5, the screen, and the collector.

Electrical Characteristics and Heater Ratings

The tube is designed with an indirectly heated cathode. The heater is rated for a nominal operating voltage of 6.3 V, drawing a current of 450 ± 20 mA. Under typical conditions, the average heater warm-up time is 11 seconds.

The direct interelectrode capacitances of the tube are:

  • Cathode to all other electrodes: 5 pF
  • Grid No. 1 to all other electrodes: 6 pF
  • External conductive coating to anode: 1000 pF minimum to 1500 pF maximum

Design-Maximum Ratings

The following design-maximum limits must be observed to prevent damage and ensure reliable operation. Unless otherwise specified, all voltage values are positive with respect to Grid No. 1.

  • Anode Voltage: 12,000 V minimum to 21,000 V maximum
  • Grid-No. 4 (Focusing) Voltage: -400 V maximum to +1250 V maximum
  • Grid-No. 2 Voltage: 25 V minimum to 60 V maximum
  • Cathode Voltage:
    • Negative peak value: 2 V maximum
    • Negative bias value: 0 V maximum
    • Positive bias value: 100 V maximum
    • Positive peak value: 150 V maximum
  • Heater Voltage: 5.7 V minimum to 6.9 V maximum
  • Grid-No. 1-Circuit Resistance: 1.5 MΩ maximum

Peak Heater-Cathode Voltage Limits

The maximum allowable potential difference between the heater and the cathode depends on the polarity and the operating state of the equipment:

  • Heater negative with respect to cathode:
    • During equipment warm-up (first 15 seconds or less): 450 V maximum
    • After equipment warm-up is complete: 300 V maximum
  • Heater positive with respect to cathode:
    • Combined AC and DC voltage: 200 V maximum
    • DC component only: 100 V maximum

Typical Operating Conditions

In typical cathode-drive service, the operating voltages are referenced positive with respect to Grid No. 1. Standard operating parameters are established as follows:

  • Anode Voltage: 16,000 V
  • Grid-No. 2 Voltage: 50 V
  • Grid-No. 4 Voltage: 250 V
  • Cathode Voltage: 32 V to 50 V (for visual extinction of the focused raster)

The optimum focus range for Grid No. 4 is 0 V to +400 V. This range is specified with the combined Grid No. 1 and video-signal voltage adjusted to produce an anode current of 100 µA on a 10-1/2 inch by 14-inch raster pattern.

Technical Summary

The 19ENP4A is a 15-pound, 114-degree magnetic deflection cathode-ray tube designed for cathode-drive television applications. It features a P4 aluminized sulfide phosphor screen, a 48% transmission filterglass faceplate, and PAN-O-PLY integral implosion protection. Operating with a nominal 6.3 V heater, the tube utilizes low-voltage electrostatic focusing (Grid No. 4) and does not require an ion-trap magnet. With an anode rating of up to 21,000 V and a typical operating anode voltage of 16,000 V, it provides a reliable, high-contrast display when its external conductive coating and implosion hardware are properly grounded.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
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
21000 V
Max screen voltage
60 V

Low-grid-2 aluminized P4 cathode-drive picture tube.

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

1971 RCA HB3 Binder 1 of 7

Published operating points and test conditions from this source.

SECTION 1

Cathode Ray

Other

  • Heater voltage

    6.3 V

  • Heater current

    450 mA

  • Heater warm-up time

    11 s

  • Maximum anode/ultor voltage

    21000 V

  • Minimum anode/ultor voltage

    12000 V

  • Typical anode/ultor voltage

    16000 V

    PictureTubeService

  • Maximum grid No.2 voltage

    60 V

  • Typical grid No.2 voltage

    50 V

    PictureTubeService

  • Focus-voltage range minimum

    0 V

    OptimumFocus

  • Focus-voltage range maximum

    400 V

    OptimumFocus

  • Visual-extinction voltage range minimum

    32 V

    FocusedRasterExtinction

  • Visual-extinction voltage range maximum

    50 V

    FocusedRasterExtinction

  • Maximum grid No.1 circuit resistance

    1.5 megohm

  • X-ray shielding warning

    Present

    HighAnodeVoltage

  • Maximum cathode positive bias voltage

    100 V

    CathodeDrive

  • Maximum cathode positive peak voltage

    150 V

    CathodeDrive

  • Maximum cathode negative peak voltage

    2 V

    CathodeDrive

  • Peak heater-cathode voltage during warm-up

    450 V

    HeaterNegative;Warmup<=15s

  • Peak heater-cathode voltage after warm-up

    300 V

    HeaterNegative

  • Peak heater-cathode voltage heater positive

    200 V

    HeaterPositive

Construction

  • Focusing method

    LowVoltageElectrostatic

  • Deflection method

    Magnetic

  • Phosphor

    P4

  • Screen type

    Aluminized white

    P4

Characteristic

  • Deflection angle

    114 deg

    Approximate

Capacitance

  • Cathode to all other electrodes capacitance

    5 pF

    Approximate

  • Grid No.1 to all other electrodes capacitance

    6 pF

    Approximate

  • External conductive coating to anode capacitance maximum

    1500 pF

    Approximate