19AVP4 — Rectangular Glass Picture Tube

The 19AVP4 is a 19-inch direct-viewed, rectangular glass cathode-ray picture tube designed for television receiver applications. It features a low-voltage electrostatic focusing system and magnetic deflection. The tube incorporates an aluminized screen with P4-Sulfide phosphor, which produces white fluorescence and white phosphorescence with a short-to-medium (or medium-short) persistence. The electron gun design eliminates the need for an external ion-trap magnet.

Mechanical and Physical Design

The 19AVP4 is constructed with a spherical faceplate made of gray filter glass, providing approximately 78% light transmission at the center to improve picture contrast under ambient light. The tube's external conductive coating must be grounded to serve as a high-voltage filter capacitor.

Dimensions and Weight

• Overall Length: 11-3/8 ± 1/4 inches
• Greatest Width: 16-13/32 ± 1/8 inches
• Greatest Height: 13-11/32 ± 1/8 inches
• Diagonal: 18-5/8 ± 1/8 inches
• Neck Diameter: 1-1/8 inches
• Neck Length: 4-1/8 ± 1/8 inches
• Minimum Useful Screen Dimensions:
  • Width: 15-1/8 inches
  • Height: 12 inches
  • Diagonal: 17-9/16 inches
  • Projected Area: 172 square inches
• Weight: Approximately 13.5 to 14 pounds
• Operating Position: Any

Heater and Electrical Connections

The 19AVP4 features a controlled-warm-up heater designed for series or parallel operation.

Heater Ratings

• Heater Voltage: 6.3 V (typical), with a design-maximum range of 5.7 V to 6.9 V
• Heater Current: 600 ± 30 mA (or 0.60 A ± 5%) at 6.3 V
• Average Heater Warm-Up Time: 11 seconds. This is defined as the time required for the heater voltage to reach 80% of its rated value when four times the rated voltage is applied in series with an impedance equal to three times the rated voltage divided by the rated current.

Base and Pinout Configuration

The tube utilizes a Small-Button Neoeightar 7-Pin base (JEDEC No. B7-208) with an 8HR basing designation. The high-voltage anode (ultor) connection is made via a recessed small cavity cap (JEDEC No. J1-21), which connects to Grid No. 3, Grid No. 5, and the collector. This cap is aligned on the same side as Pin No. 4, within 30° of the horizontal centerline.

Depending on the specific production design, the 8HR base is wired in one of two configurations:

Both configurations share the same connections for Pin 3 (Grid No. 2), Pin 4 (Grid No. 4), Pin 6 (Grid No. 1), and Pin 8 (Heater), but swap the roles of Pin 1, Pin 2, and Pin 7.

Interelectrode Capacitances

The direct interelectrode capacitances of the 19AVP4 are approximately:

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

Grid-Drive Service

In grid-drive operation, electrode voltages are referenced to the cathode.

Design-Maximum Ratings

• Ultor Voltage: 15,000 V Min to 23,000 V Max
• Grid No. 4 (Focusing) Voltage: -550 V to +1100 V
• Grid No. 2 Voltage: 200 V Min to 550 V Max
• Grid No. 1 Voltage:
  • Negative-bias value: 154 V Max
  • Negative-peak value: 220 V Max
  • Positive-bias value: 0 V Max
  • Positive-peak value: 2 V Max
• Peak Heater-Cathode Voltage:
  • Heater negative to cathode during warm-up (≤ 15 s): 450 V Max
  • Heater negative to cathode after warm-up: 200 V Max
  • Heater positive to cathode: 200 V Max

Typical Operating Conditions

• Ultor Voltage: 20,000 V
• Grid No. 4 Voltage for Focus: 0 to 400 V
• Grid No. 2 Voltage: 400 V
• Grid No. 1 Voltage for Visual Extinction of Focused Raster: -36 to -94 V (some specifications narrow this typical range to -46 to -94 V). Cutoff of an undeflected focused spot increases the absolute bias value by approximately 5 V.
• Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms

Cathode-Drive Service

In cathode-drive operation, electrode voltages are referenced to Grid No. 1.

Design-Maximum Ratings

• Ultor-to-Grid No. 1 Voltage: 15,000 V Min to 23,000 V Max
• Grid No. 4-to-Grid No. 1 Voltage: -400 V to +1250 V
• Grid No. 2-to-Grid No. 1 Voltage: 350 V Min to 700 V Max
• Grid No. 2-to-Cathode Voltage: 550 V Max
• Cathode-to-Grid No. 1 Voltage:
  • Positive-bias value: 154 V Max
  • Positive-peak value: 220 V Max
  • Negative-bias value: 0 V Max
  • Negative-peak value: 2 V Max
• Peak Heater-Cathode Voltage: Same as Grid-Drive Service

Typical Operating Conditions

• Ultor-to-Grid No. 1 Voltage: 20,000 V
• Grid No. 4-to-Grid No. 1 Voltage for Focus: 0 to 400 V
• Grid No. 2-to-Grid No. 1 Voltage: 400 V
• Cathode-to-Grid No. 1 Voltage for Visual Extinction of Focused Raster: 36 to 78 V (some specifications narrow this typical range to 42 to 78 V). Cutoff of an undeflected focused spot increases the absolute bias value by approximately 5 V.
• Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms

Raster Cutoff Characteristics

The raster cutoff voltage depends on the applied Grid No. 2 potential:

• Grid-Drive Cutoff: At a heater voltage of 6.3 V and an ultor voltage of 15,000 to 23,000 V, the Grid No. 1 cutoff voltage ranges from approximately -25 V to -60 V when Grid No. 2 is at 200 V. This cutoff range shifts to approximately -50 V to -125 V when Grid No. 2 is increased to 560 V.
• Cathode-Drive Cutoff: At a heater voltage of 6.3 V and an ultor-to-grid voltage of 15,000 to 23,000 V, the Cathode-to-Grid No. 1 cutoff voltage ranges from approximately 30 V to 70 V when the Grid No. 2-to-Grid No. 1 voltage is 350 V. This cutoff range shifts to approximately 60 V to 130 V when the Grid No. 2-to-Grid No. 1 voltage is increased to 700 V.

Operating Considerations and Safety

Centering Magnet

An adjustable centering magnet may be used with the 19AVP4. The maximum field strength of this magnet is calculated using the following formula:

$\text{Maximum Field Strength} = \sqrt{\frac{E_{\text{ultor}}}{16000}} \times 8 \text{ gausses}$

Where $E_{\text{ultor}}$ is the ultor voltage (either $E_{c5k}$ in grid-drive or $E_{c5g1}$ in cathode-drive) in volts. Under typical operating conditions (20,000 V), this yields a maximum field strength of 0 to 9 gausses. The physical distance from the reference line to the permanent magnet centering magnet must not exceed 2-1/4 inches.

X-Ray Radiation and Implosion Protection

• X-Ray Warning: The 19AVP4 does not produce harmful X-ray radiation at operating voltages up to 16,000 V. However, if the tube is operated above 16,000 V (up to its design-maximum of 23,000 V), shielding may be required to protect against prolonged close-range exposure.
• Shatter-Proof Cover: Because of the risk of high-vacuum implosion, the tube must be operated with a protective, shatter-proof glass cover over the faceplate. This cover can also serve as additional X-ray shielding if required.

Technical Summary

The 19AVP4 is a 19-inch rectangular glass picture tube featuring a 114° diagonal deflection angle, low-voltage electrostatic focusing, and magnetic deflection. Equipped with an aluminized P4-Sulfide phosphor screen, it provides a bright white display with short-to-medium persistence without requiring an ion-trap magnet. It operates with a 6.3 V, 600 mA heater featuring a controlled 11-second warm-up time. The tube supports both grid-drive and cathode-drive configurations, with a design-maximum ultor rating of 23,000 V. Safe operation requires grounding the external conductive coating, utilizing a shatter-proof faceplate cover, and providing appropriate X-ray shielding when operated above 16,000 V.