19YP4 — Television Picture Tube

The 19YP4 is a 19-inch direct-viewed, short rectangular glass television picture tube. It features a spherical faceplate made of gray filter glass, an aluminized screen with P4-Sulfide phosphor, and low-voltage (or Tri-Potential) electrostatic focusing. The tube utilizes magnetic deflection with a wide diagonal deflection angle of 114° and does not require an ion-trap magnet. It is designed with a short neck and an external conductive coating that must be grounded during operation.

Mechanical and Physical Construction

The 19YP4 is housed in a J149A1 glass bulb with a short neck, measuring 3-9/16 ± 1/8 inches in length and 1-1/8 inches in diameter, with a maximum neck diameter at the splice of 1.168 inches. The overall length of the tube is 10-13/16 ± 1/4 inches.

The screen has a minimum useful projected area of 172 square inches, with minimum useful screen dimensions of 15-1/8 inches in width and 12 inches in height. The diagonal dimension of the faceplate is 18-5/8 ± 1/8 inches, while the greatest physical width and height of the bulb are 16-13/32 ± 1/8 inches and 13-11/32 ± 1/8 inches, respectively. The tube weighs approximately 13-1/2 to 14 pounds.

The faceplate is constructed of gray filter glass providing approximately 78% light transmission at the center. The aluminized screen utilizes P4-Sulfide phosphor, which exhibits white fluorescence and phosphorescence with medium-short to short-to-medium persistence.

Deflection is achieved magnetically, with approximate deflection angles of:

• Diagonal: 114°
• Horizontal: 102° to 103°
• Vertical: 85° to 86°

Electrical Connections and Pinout

The 19YP4 uses a Small-Button Neoeightar 7-Pin base (JEDEC No. B7-208) with an 8JR basing designation. High-voltage connection to the anode (ultor) is made via a Recessed Small Cavity Cap (JEDEC No. J1-21) located on the bulb envelope, which is aligned with Pin 4 within an angular tolerance of 30°.

The pin connections, viewed from the bottom of the base, are as follows:

Heater Ratings

The heater is designed for controlled warm-up service with the following parameters:

• Nominal Heater Voltage: 6.3 V (AC or DC)
• Heater Voltage Range (Design-Maximum): 5.7 V to 6.9 V
• Heater Current (at 6.3 V): 600 mA (with a tolerance of ±5% or ±30 mA)
• Average Warm-Up Time: 11 seconds

Interelectrode Capacitances

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

Operating Conditions and Drive Services

The 19YP4 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 service, voltages are referenced to the cathode.

Design-Maximum Ratings

• Anode (Ultor) Voltage: 11,000 V to 20,000 V DC
• Grid No. 3 (Focusing) Voltage: -350 V to +700 V DC
• Grid No. 2 Voltage: 300 V to 600 V DC
• Grid No. 1 Voltage:
  • Negative-bias value: 154 V or 155 V DC
  • Negative-peak value: 220 V
  • Positive-bias value: 0 V DC
  • Positive-peak value: 2 V

Typical Operating Conditions

• Anode Voltage: 16,000 V DC
• Grid No. 3 Voltage for Focus: 0 to 400 V DC
• Grid No. 2 Voltage: 500 V DC
• Grid No. 1 Voltage for Visual Extinction of Focused Raster (Cutoff): -43 V to -78 V DC

Cutoff Behavior

The Grid No. 1 cutoff voltage varies linearly with Grid No. 2 voltage. At a Grid No. 2 voltage of 300 V, cutoff occurs between -25 V and -50 V. At a Grid No. 2 voltage of 600 V, cutoff shifts to between -52 V and -92 V.

Cathode-Drive Service

In Cathode-Drive service, voltages are referenced to Grid No. 1.

Design-Maximum Ratings

• Anode-to-Grid No. 1 Voltage: 11,000 V to 20,000 V DC
• Grid No. 3-to-Grid No. 1 Voltage: -200 V to +850 V DC
• Grid No. 2-to-Grid No. 1 Voltage: 450 V to 750 V DC
• Grid No. 2-to-Cathode Voltage: 600 V DC
• Cathode-to-Grid No. 1 Voltage:
  • Positive-bias value: 154 V or 155 V DC
  • Positive-peak value: 220 V
  • Negative-bias value: 0 V DC
  • Negative-peak value: 2 V

Typical Operating Conditions

• Anode-to-Grid No. 1 Voltage: 16,000 V DC
• Grid No. 3-to-Grid No. 1 Voltage for Focus: 0 to 400 V DC
• Grid No. 2-to-Grid No. 1 Voltage: 500 V DC
• Cathode-to-Grid No. 1 Voltage for Visual Extinction of Focused Raster (Cutoff): 41 V to 69 V DC

Cutoff Behavior

The Cathode-to-Grid No. 1 cutoff voltage varies linearly with the Grid No. 2-to-Grid No. 1 voltage. At a Grid No. 2-to-Grid No. 1 voltage of 450 V, cutoff occurs between 38 V and 62 V. At a Grid No. 2-to-Grid No. 1 voltage of 750 V, cutoff shifts to between 58 V and 102 V.

Heater-Cathode Voltage Ratings (Both Services)

• Heater negative with respect to cathode:
  • During warm-up period (≤ 15 seconds): 450 V max
  • After equipment warm-up: 200 V max
• Heater positive with respect to cathode: 200 V max

Limiting Circuit Values

• Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms
• Minimum Grid No. 2 and Grid No. 3 Circuit Resistance: 10,000 Ohms (protective resistance is advised to prevent damage from internal arcing)

Focus and Centering Characteristics

The low-voltage electrostatic focusing system (Grid No. 3) typically requires a voltage between 0 and 400 V DC to achieve optimum focus. This focus voltage is dynamic and varies based on other operating parameters:

• It increases directly with anode voltage at a rate of approximately 46 V per 1000 V change in anode potential.
• It decreases inversely with Grid No. 2 voltage at a rate of approximately 60 V per 100 V change in Grid No. 2 potential.
• It decreases inversely with anode current at a rate of approximately 60 V per 100 µA change in anode current.

Centering Magnet

A permanent magnet (PM) centering magnet may be positioned at a distance not exceeding 2-1/4 inches from the reference line. The maximum field strength of this magnet is dependent on the anode voltage and is calculated using the following formula:

$\text{Max Field Strength} = \sqrt{\frac{E_{\text{anode}}}{16000}} \times 10\text{ gausses}$

Where $E_{\text{anode}}$ is represented by $E_{c4k}$ in Grid-Drive service or $E_{c4g1}$ in Cathode-Drive service. Under typical operating conditions at 16,000 V, the maximum field strength is 10 gausses.

Safety and Operational Warnings

• X-ray Radiation: X-ray shielding may be required if the tube is operated at anode voltages exceeding 16,000 V.
• Grounding: The external conductive coating must be reliably grounded to prevent electrical shock and ensure proper operation.

Technical Summary

The 19YP4 is a high-performance, 19-inch rectangular television picture tube utilizing low-voltage electrostatic focus and 114° magnetic deflection. Featuring a short neck design, a spherical gray filterglass faceplate with 78% light transmission, and an aluminized P4-Sulfide phosphor screen, it provides a minimum useful projected area of 172 square inches without requiring an ion-trap magnet. Operating typically at an anode voltage of 16,000 V, the tube supports both Grid-Drive and Cathode-Drive configurations with a controlled 11-second heater warm-up time. Its design-maximum ratings, linear cutoff characteristics, and protective circuit requirements ensure reliable operation in television receiver applications.