19EHP4

The 19EHP4 is a 19-inch direct-viewed, rectangular glass television picture tube. It features electrostatic focusing and magnetic deflection, utilizing a low anode voltage design. The tube incorporates an aluminized P4 phosphor screen, a gray filter glass faceplate, and integral implosion protection via a banded rimband system. It does not require an ion trap.

Mechanical Design and Physical Dimensions

The 19EHP4 is constructed using a J149F glass bulb with a neck diameter of 1 1/8 inches. It features a recessed small cavity cap (J1-21) for the high-voltage anode contact and a B7-208 base. The physical dimensions and mechanical limits of the tube are as follows:

• Overall Length: 11 5/8 ± 1/4 inches
• Neck Length: 4 3/8 ± 1/8 inches
• Minimum Useful Screen Dimensions:
  • Height: 12 inches
  • Width: 15 3/16 inches
  • Diagonal: 17 9/16 inches
• Minimum Useful Screen Area: 172 square inches
• Weight: Approximately 15 pounds

The faceplate is made of gray filter glass with approximately 49% light transmittance to improve contrast. The screen uses an aluminized P4 phosphor, which exhibits white fluorescence and medium-short persistence.

Deflection and Alignment

The tube utilizes magnetic deflection with the following approximate deflection angles:

• Horizontal: 101°
• Diagonal: 114°
• Vertical: 86°

The 8HR basing arrangement requires specific physical alignment. Base pin number 4 (the focusing electrode) aligns with the horizontal centerline (A-A') within a tolerance of 30° and is positioned on the same side of the neck as the recessed anode contact.

Electrical Connections and Basing

The 19EHP4 uses an 8-pin base designated as Basing 8HR. The pin connections, viewed from the bottom of the base, are assigned as follows:

Note that Pin 5 is omitted from the active connections in this basing configuration.

Heater Ratings and Capacitances

The heater is designed for a nominal voltage of 6.3 Volts and a current of 0.60 Ampere (with a tolerance of ± 5%). The heater warm-up time is rated at 11 seconds. This warm-up period is defined as the time required for the heater to reach 80% of its rated voltage when operated in series with a resistance equal to three times the rated heater resistance at four times the rated voltage.

Interelectrode Capacitances

The approximate capacitances between the internal elements and external structures are:

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

The electrical resistance between the external conductive coating and the rimband must be a minimum of 50 Megohms.

Operating Modes and Design-Maximum Ratings

The 19EHP4 can be operated in either Grid Drive or Cathode Drive configurations. The design-maximum ratings and typical operating conditions differ depending on the chosen drive service.

Grid Drive Service

In Grid Drive configuration, control signals are applied to Grid No. 1.

• Anode Voltage: 10,000 Volts DC (minimum) to 18,000 Volts DC (maximum)
• Grid No. 4 (Focusing Electrode) Voltage: -550 to ±1100 Volts DC
• Grid No. 2 Voltage: 200 Volts DC (minimum) to 550 Volts DC (maximum)
• Grid No. 1 Voltage:
  • Negative bias value: 155 Volts DC (maximum)
  • Negative peak value: 220 Volts (maximum)
  • Positive bias value: 0 Volts DC (maximum)
  • Positive peak value: 2 Volts (maximum)
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode (during warm-up period ≤ 15 seconds): 450 Volts (maximum)
  • Heater negative with respect to cathode (after warm-up): 200 Volts (maximum)
  • Heater positive with respect to cathode: 200 Volts (maximum)

Cathode Drive Service

In Cathode Drive configuration, control signals are applied to the cathode.

• Anode Voltage: 10,000 Volts DC (minimum) to 18,000 Volts DC (maximum)
• Grid No. 4 (Focusing Electrode) Voltage: -400 to +1250 Volts DC
• Grid No. 2 Voltage: 350 Volts DC (minimum) to 700 Volts DC (maximum)
• Cathode Voltage:
  • Positive bias value: 155 Volts DC (maximum)
  • Positive peak value: 220 Volts (maximum)
  • Negative bias value: 0 Volts DC (maximum)
  • Negative peak value: 2 Volts (maximum)
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode (during warm-up period ≤ 15 seconds): 450 Volts (maximum)
  • Heater negative with respect to cathode (after warm-up): 300 Volts (maximum)
  • Heater negative with respect to cathode (DC component): 200 Volts DC (maximum)
  • Heater positive with respect to cathode: 200 Volts (maximum)
  • Heater positive with respect to cathode (DC component): 100 Volts DC (maximum)

Typical Operating Conditions

The typical operating parameters for both drive configurations are established at an anode voltage of 16,000 Volts DC:

Circuit and Safety Requirements

To ensure stable and safe operation, the following circuit values and safety precautions must be observed:

• Grid No. 1 Circuit Resistance: The maximum allowable resistance in the Grid No. 1 circuit is 1.5 Megohms.
• Grounding: The external conductive coating and the rimbands must be securely connected to the chassis ground. This grounding is necessary to utilize the capacitance between the coating and the anode as a filter capacitor.
• X-ray Radiation Warning: The 19EHP4 may produce X-rays when operated. Adequate shielding must be provided if the tube is operated at voltages higher than 16,000 Volts, or higher than the maximum rated anode voltage of 18,000 Volts, whichever of these two values is less.