19ACP4 — Television Picture Tube

The 19ACP4 is a rectangular glass television picture tube designed for use in television receivers. It features a 114-degree magnetic deflection system and a low-voltage electrostatic focusing system. The tube incorporates an aluminized screen with a P4 phosphor, a gray filter glass, and a spherical faceplate. It has a minimum useful projected screen area of 172 square inches. The 19ACP4 operates without the need for an ion trap and includes an external conductive coating that acts as a supplementary filter capacitor when grounded.

Mechanical Specifications and Physical Dimensions

The 19ACP4 utilizes a J149 glass bulb with a B7-208 base and an 8HR basing configuration. The anode connection is made via a J1-21 recessed small cavity cap.

Physical Dimensions

• Overall Length: 12-3/8 ± 1/4 inches
• Neck Length: 5-1/8 ± 1/8 inches
• Greatest Diagonal Dimension: 18-5/8 ± 1/8 inches
• Greatest Width: 16-13/32 ± 1/8 inches
• Greatest Height: 13-11/32 ± 1/8 inches
• Maximum Neck Diameter (at splice): 1.168 inches
• Weight: 13-1/2 lbs.

Screen Characteristics

• Minimum Useful Screen Dimensions (Projected):
  • Diagonal: 17-9/16 inches
  • Horizontal: 15-1/8 inches
  • Vertical: 12 inches
• Minimum Useful Projected Area: 172 square inches
• Phosphor: Aluminized P4
• Faceplate: Spherical gray filter glass

Installation and Handling Precautions

To prevent damage to the tube and ensure safe operation, several mechanical constraints must be observed:

• Base Pin Strain: Lateral strains on the base pins must be avoided. The socket should be equipped with flexible leads. The base wafer perimeter fits inside a 1-3/4 inch diameter circle concentric with the tube axis.
• Anode Terminal Alignment: The alignment of the anode cap terminal with Pin 4 has an angular tolerance of ±30° about the tube axis.
• Centering Magnet: If a permanent magnet (PM) centering magnet is used, it should provide a field of 0 to 8 gauss and must not extend more than 2-1/8 inches from the Yoke Reference Line.

Heater and Electrical Characteristics

Heater Ratings

The heater is designed for operation in series-string or parallel configurations.

• Heater Voltage: 6.3 V
• Heater Current: 600 ± 30 mA
• Heater Warm-up Time: 11 seconds. This warm-up time is defined as the time required to reach 80% of the rated heater voltage when tested in series with a resistance equal to three times the rated heater voltage divided by the rated heater current, after applying four times the rated heater voltage.

Pinout and Basing (8HR)

The 19ACP4 uses an 8-pin base with the 8HR basing arrangement. Depending on the specific wiring standard applied, there is a variation in the assignment of Pin 1 and Pin 2:

• Configuration A: Pin 1 is Grid No. 1, Pin 2 is the Heater.
• Configuration B: Pin 1 is the Heater, Pin 2 is Grid No. 1.

The remaining pin connections are consistent across both configurations:

• Pin 3: Grid No. 2
• Pin 4: Grid No. 4 (Focusing Electrode)
• Pin 6: Grid No. 1
• Pin 7: Cathode
• Pin 8: Heater
• Recessed Cavity Cap: Anode (Grids No. 3 and No. 5, Screen, Collector)

Electrostatic Capacitances

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

The external conductive coating must be grounded to the receiver chassis to utilize its properties as a supplementary high-voltage filter capacitor.

Design-Maximum Ratings

The ratings below are established under the Design-Maximum System. Unless otherwise specified, all voltage values are positive with respect to Grid No. 1.

Operation of the tube below the minimum recommended anode voltage of 12,000 V is not recommended, as both screen brilliance and picture definition decrease significantly.

Typical Operating Conditions (Cathode Drive Service)

In typical cathode-drive applications, all voltages are specified as positive with respect to Grid No. 1:

• Anode Voltage: 14,000 V DC
• Grid No. 4 (Focusing Electrode) Voltage: 0 to 400 V DC
• Grid No. 2 Voltage: 50 V DC
• Cathode Voltage for Raster Cutoff: 35 to 50 V DC

Limiting Circuit Values

To protect the tube from internal arcing and damage, the following circuit resistance limits must be maintained:

• Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms
• Minimum Grid No. 2 and Grid No. 4 Circuit Resistance: 10,000 Ohms. A protective series resistance of at least this value is highly advisable in the Grid No. 2 and Grid No. 4 electrode circuits.

Safety and Operating Warnings

• X-Ray Radiation: When the 19ACP4 is operated at anode voltages exceeding 16,000 V, it may produce soft X-rays. Appropriate shielding must be provided in the receiver design to limit exposure and ensure operator safety.
• High Voltage and Grounding: The external conductive coating must be securely grounded. This coating, in conjunction with the internal anode, forms a high-voltage filter capacitor that can retain a lethal charge even after the receiver is turned off. Proper discharge procedures must be followed before handling the tube.

Technical Summary

The 19ACP4 is a 114-degree magnetic deflection, low-voltage electrostatically focused rectangular television picture tube. It features an aluminized P4 phosphor screen with a spherical gray filter glass faceplate providing a minimum useful projected area of 172 square inches. Operating with a 6.3 V, 600 mA heater, the tube features a controlled 11-second warm-up time. It is rated for a maximum anode voltage of 20,000 V (with a recommended minimum of 12,000 V) and is typically operated in cathode-drive service with an anode potential of 14,000 V. The tube requires no ion trap, utilizes an 8HR basing configuration, and incorporates an external conductive coating that must be grounded to serve as a supplementary filter capacitor.