19AFP4 — Rectangular Television Picture Tube

The 19AFP4 is a 19-inch direct-viewed rectangular glass television picture tube designed for black-and-white receiver applications. It features a low-voltage electrostatic focusing system, a 114-degree magnetic deflection system, and an aluminized screen with an integrated protective safety panel. The tube is constructed with a space-saving short neck and does not require an external ion-trap magnet.

Mechanical Construction and Optical Characteristics

The 19AFP4 is built using a bi-panel rectangular glass envelope (bulb designation J149C) with a spherical faceplate. Laminated directly to the front of the tube is a gray filter glass safety plate (type FP159A), which serves as an integrated protective shield. This safety panel provides a light transmittance of approximately 44%, enhancing picture contrast under ambient lighting conditions.

The screen utilizes an aluminized P4-Sulfide type phosphor that produces white fluorescence with short-to-medium persistence. The tube provides a minimum useful screen area of 172 to 174 square inches, with typical minimum useful dimensions of 12-1/16 inches in height, 15-1/4 inches in width, and a diagonal of 17-1/4 to 17-3/4 inches.

The deflection system is purely magnetic, requiring no ion-trap magnet. The nominal deflection angles are:

• Diagonal: 114°
• Horizontal: 102°
• Vertical: 86°

The physical dimensions and mechanical features of the tube include:

• Overall Length: 11-5/8 inches (with a tolerance of ±3/16 or ±5/16 inch)
• Neck Length: 4-1/8 ± 1/8 inches
• Weight: Approximately 18.5 lbs
• Bulb Contact: Recessed Small Cavity Cap (JEDEC No. J1-21)
• Base: Small-Button Neoeightar 7-Pin (JEDEC No. B7-208)
• Operating Position: Any

An external conductive coating (regular band type) is applied to the envelope. This coating must be grounded to the receiver chassis, with the grounding contact area located near the reference line.

Heater and Basing Configurations

The 19AFP4 is equipped with an indirectly heated cathode. The heater is designed with a controlled warm-up time for use in series-string or parallel-connected receiver designs.

• Heater Voltage: 6.3 V
• Heater Current: 600 mA ± 5% (0.60 A ± 5%)
• Average Warm-Up Time: 11 seconds
• Calculated Nominal Heater Power: 3.78 W (derived from 6.3 V multiplied by 0.60 A)

The tube utilizes the 8HR bottom-view basing designation. The electrical connections are documented in two distinct pinout configurations:

Basing Configuration A

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

Basing Configuration B

• Pin 1: Heater
• Pin 2: Grid No. 2
• Pin 3: Grid No. 4 (Focusing Electrode)
• Pin 4: No Connection (aligns within 30° of the horizontal centerline)
• Pin 6: Grid No. 1
• Pin 7: Cathode
• Pin 8: Heater
• Cap: Anode (J1-21)

Electrical Characteristics and Capacitances

The electrostatic focusing lens (Grid No. 4) operates at low voltages, while the high-voltage ultor/anode accelerates the electron beam. The direct interelectrode capacitances of the tube are:

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

The external conductive coating forms a capacitor with the internal anode coating, which acts as a high-voltage filter capacitor when the external coating is properly grounded.

Design-Maximum Ratings

The 19AFP4 can be operated under either Grid Drive Service or Cathode Drive Service. The design-maximum ratings represent the limiting values of operating and environmental conditions that should not be exceeded under any circumstances.

Grid Drive Service Ratings

All voltages are positive with respect to the cathode unless otherwise specified.

• Anode/Ultor Voltage: 20,000 V dc maximum
• Grid No. 4 (Focusing Electrode) Voltage: -550 to +1100 V dc
• Grid No. 2 Voltage: 550 V dc maximum
• Grid No. 1 Voltage:
  • Negative bias value: 155 V dc maximum
  • Negative peak value: 220 V maximum
  • Positive bias value: 0 V dc maximum
  • Positive peak value: 2 V maximum

Cathode Drive Service Ratings

All voltages are positive with respect to Grid No. 1 unless otherwise specified.

• Anode/Ultor Voltage: 20,000 V dc maximum
• Grid No. 4 (Focusing Electrode) Voltage: -400 to +1250 V dc
• Grid No. 2 Voltage: 700 V dc maximum
• Cathode Voltage:
  • Positive bias value: 155 V dc maximum
  • Positive peak value: 220 V maximum
  • Negative bias value: 0 V dc maximum
  • Negative peak value: 2 V maximum

Peak Heater-Cathode Voltage (Both Services)

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

Typical Operating Conditions and Circuit Values

Typical operating parameters are established for both drive configurations at an anode voltage of 16,000 V dc.

Grid Drive Operation

• Anode Voltage: 16,000 V dc
• Grid No. 2 Voltage: 300 V dc or 400 V dc
• Grid No. 4 Voltage for Focus: 0 to 400 V dc
• Grid No. 1 Voltage for Visual Extinction of Focused Raster: -35 to -72 V dc (at 300 V on Grid No. 2)
• Grid No. 1 Voltage Required for Cutoff: -46 to -94 V dc (at 400 V on Grid No. 2)

Cathode Drive Operation

• Anode Voltage: 16,000 V dc
• Grid No. 2 Voltage: 400 V dc
• Grid No. 4 Voltage for Focus: 0 to 400 V dc
• Cathode Voltage Required for Cutoff: 42 to 78 V dc

Circuit Constraints

• Grid No. 1 Circuit Resistance: 1.5 MΩ maximum

Raster Cutoff Dynamics

For complete cutoff of the undeflected focused spot, the absolute value of the bias voltage between the cathode and Grid No. 1 must be increased by approximately 5 V compared to the voltage required for the visual extinction of a focused raster.

Safety and X-ray Shielding

When operating the 19AFP4, safety precautions regarding potential X-ray radiation must be observed. If the tube is operated at anode voltages exceeding 16,000 V, or at the maximum rated anode voltage of 20,000 V (whichever is less), appropriate shielding may be required to protect users from exposure to X-rays.

Technical Summary

The 19AFP4 is a 19-inch rectangular glass picture tube featuring 114° magnetic deflection, low-voltage electrostatic focus, and an integrated FP159A safety panel with ~44% light transmittance. Operating with a 6.3 V, 600 mA heater that has an 11-second controlled warm-up time, it is highly suited for both series and parallel television receiver designs. The tube supports both Grid Drive and Cathode Drive configurations, with an absolute maximum anode rating of 20,000 V and typical operation at 16,000 V. It requires no ion-trap magnet and relies on a grounded external conductive coating to complete its high-voltage filtering system.