19DKP4 — Television Picture Tube

A 19-inch direct-viewed rectangular glass cathode-ray tube featuring a bonded shield, electrostatic focus, 114-degree magnetic deflection, and an aluminized screen.

Overview

The 19DKP4 is a rectangular glass television picture tube designed for direct-view receiver applications. It features a 19-inch diagonal screen with an aluminized P4 phosphor that produces white fluorescence with medium-short persistence. The tube employs electrostatic focusing and a wide-angle 114-degree magnetic deflection system, allowing for a relatively short overall length.

A key mechanical feature of the 19DKP4 is its bonded shield construction, which laminates a gray filterglass safety plate directly to the face of the tube. This design eliminates the need for a separate cabinet-mounted safety glass. The tube does not require an ion trap and includes an external conductive coating that, when grounded, forms a high-voltage filter capacitor in conjunction with the internal anode coating.

Mechanical and Optical Specifications

The 19DKP4 is built using a J149C glass bulb and a B7-208 base. The physical dimensions and screen characteristics are tightly controlled to ensure compatibility with standard television chassis designs:

• Overall Length: 11 9/16 ± 5/16 inches
• Neck Length: 4 1/8 ± 1/8 inches
• Neck Diameter: 1 1/8 inches (1.125 inches nominal, with tolerances of +0.043 and -0.025 inches)
• Weight: Approximately 15 1/2 lbs
• Deflection Angles (Approximate):
  • Diagonal: 114°
  • Horizontal: 101°
  • Vertical: 86°
• Minimum Useful Screen Dimensions:
  • Height: 12 1/16 inches
  • Width: 15 1/4 inches
  • Diagonal: 17 9/16 to 17 5/8 inches
  • Area: 172 square inches

The faceplate assembly consists of the tube's faceplate and an FP149B2 safety plate, which is 1/8-inch thick and has a light transmittance of 55%. The combined laminated assembly provides an overall light transmittance of approximately 45%, enhancing picture contrast under ambient lighting conditions.

Heater and Basing Configuration

The 19DKP4 uses an indirectly heated, unipotential cathode. The heater is designed with a controlled warm-up time of 11 seconds to facilitate operation in series-string receiver configurations.

The tube utilizes the 8HR basing diagram, which provides connections through a 7-pin base (B7-208) and a separate high-voltage anode contact. The anode connection is made via a recessed small cavity cap (J1-21) located on the bulb cone.

Interelectrode Capacitances

The electrical isolation and capacitive loading of the gun structure are characterized by the following approximate values:

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

The capacitance between the external conductive coating and the internal anode coating serves as a filter capacitor for the high-voltage power supply, helping to stabilize the anode voltage during rapid beam current transitions.

Operating Modes and Design-Maximum Ratings

The 19DKP4 can be operated in either Grid Drive Service (where the video signal is applied to Grid No. 1 and the cathode is held at a reference bias) or Cathode Drive Service (where the video signal is applied to the cathode and Grid No. 1 is held at a reference bias). The design-maximum ratings and typical operating conditions are optimized separately for each mode.

Grid Drive Service

In Grid Drive configuration, the control grid (Grid No. 1) modulates the electron beam.

• Design-Maximum Ratings:

  • Anode Voltage: 15,000 V dc (Min) to 23,000 V dc (Max)
  • Grid No. 4 (Focusing Electrode) Voltage: -550 to +1100 V dc
  • Grid No. 2 Voltage: 200 V dc (Min) to 550 V dc (Max)
  • Grid No. 1 Voltage:
    • Negative Bias: 155 V dc
    • Negative Peak: 220 V
    • Positive Bias: 0 V dc
    • Positive Peak: 2 V
  • Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms

• Typical Operating Conditions:

  • Anode Voltage: 20,000 V dc
  • Grid No. 4 Voltage (for focus): 0 to 400 V dc
  • Grid No. 2 Voltage: 400 V dc
  • Grid No. 1 Voltage for Cutoff: -46 to -94 V dc

Cathode Drive Service

In Cathode Drive configuration, the cathode potential is modulated to control the beam current, which often permits lower drive voltage requirements.

• Design-Maximum Ratings:

  • Anode Voltage: 15,000 V dc (Min) to 23,000 V dc (Max)
  • Grid No. 4 (Focusing Electrode) Voltage: -400 to +1250 V dc
  • Grid No. 2 Voltage: 350 V dc (Min) to 700 V dc (Max)
  • Cathode Voltage:
    • Positive Bias: 155 V dc
    • Positive Peak: 220 V
    • Negative Bias: 0 V dc
    • Negative Peak: 2 V

• Typical Operating Conditions:

  • Anode Voltage: 20,000 V dc
  • Grid No. 4 Voltage (for focus): 0 to 400 V dc
  • Grid No. 2 Voltage: 400 V dc
  • Cathode Voltage for Cutoff: 42 to 78 V dc

Heater-Cathode Voltage Limits

To prevent insulation breakdown between the heater and the cathode, the potential difference between these elements must not exceed the following design-maximum limits in either operating mode:

• Heater negative with respect to cathode:
  • During warm-up (first 15 seconds or less): 450 V peak
  • After warm-up: 200 V peak (or dc)
• Heater positive with respect to cathode: 200 V peak (or dc)

Technical Summary

The 19DKP4 is a highly integrated 19-inch television picture tube that combines a space-saving 114-degree magnetic deflection angle with electrostatic focusing. Its bonded safety shield faceplate provides robust protection and high contrast with a 45% light transmittance. Capable of operating at anode potentials up to 23,000 V, the tube supports both grid-drive and cathode-drive configurations, offering flexible design options for television receiver designers.