19BFP4 — Television Picture Tube

The 19BFP4 is a direct-view rectangular glass television picture tube designed for use in television receivers. It features a short straight electron gun that eliminates the need for an ion trap, low-voltage electrostatic focusing, and 92-degree magnetic deflection. The tube incorporates a gray-tinted faceplate and a metal-backed screen with P4 aluminized phosphor, providing white fluorescence with medium persistence.

Mechanical Specifications and Physical Dimensions

The 19BFP4 is constructed with a rectangular glass bulb (J149B1) and a spherical faceplate. The screen has a minimum useful projected area of approximately 172 square inches, with minimum useful dimensions of 15-1/8 inches in width by 12 inches in height. The physical dimensions and mechanical characteristics of the tube are detailed below:

The J1-21 anode contact aligns with pin position No. 6 within a tolerance of ±30 degrees on the same side as the anode terminal.

Heater, Basing, and Interelectrode Capacitances

The 19BFP4 utilizes an indirectly heated cathode with a controlled warm-up time. The heater and electrical connection parameters are as follows:

• Heater Voltage: 6.3 V
• Heater Current: 600 mA ± 5% (0.6 A ± 5%)
• Heater Warm-up Time: 11 seconds

Pin Connections (Bottom View - Basing 12L)

The electrical connections are made through a 6-pin small shell duodecal base:

Interelectrode Capacitances

The approximate capacitances between the electrodes are:

• Cathode to all other electrodes: ~5 pF (uuf)
• Grid No. 1 to all other electrodes: ~6 pF (uuf)
• External conductive coating to anode: 1000 pF (minimum) to 2000 pF (maximum)

The external conductive coating forms a supplementary filter capacitor when grounded, which is a requirement for proper circuit operation.

Design-Maximum Ratings

The design-maximum ratings represent the limiting values of operating and environmental conditions under which the tube can safely operate. These ratings must not be exceeded:

• Anode Voltage: 20,000 V DC maximum, 11,000 V DC minimum
• Grid No. 4 Voltage (Focusing Electrode): -550 to +1100 V DC maximum
• Grid No. 2 Voltage: 550 V DC maximum (or up to 700 V DC maximum depending on the specific rating system applied)
• Grid No. 1 Voltage (Grid Drive):
  • Negative bias value: 154 V DC maximum
  • Positive bias value: 0 V DC maximum
  • Positive peak value: 2 V
• Cathode Voltage (Cathode Drive):
  • DC negative value: 0 V minimum
  • Negative peak value: 2 V
  • DC positive value: 154 V maximum
  • Positive peak value: 220 V
• Heater-Cathode Voltage:
  • Heater negative with respect to cathode: 450 V DC maximum during the warm-up period (not to exceed 15 seconds); 200 V DC maximum after warm-up.
  • Heater positive with respect to cathode: 200 V DC maximum.

Operating Conditions and Circuit Design

The 19BFP4 can be operated in either cathode-drive or grid-drive configurations. Typical operating conditions for these services are outlined below:

Typical Operating Points

Under grid-drive conditions, the Grid No. 4 voltage is specified for focus with an anode current of 100 µA and a 15-1/8" x 12" raster. Visual extinction of the focused raster occurs within the specified Grid No. 1 voltage range, while the extinction of a stationary focused spot requires approximately 5 V more negative bias. Under cathode-drive conditions, operating Grid No. 2 below 300 V is not recommended.

Limiting Circuit Values

• Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms
• Minimum Grid No. 2 & Grid No. 4 Circuit Resistance: 10,000 Ohms (protective resistance is recommended in these circuits)

Installation and Handling Precautions

• X-Ray Radiation: When operated at anode voltages above 16,000 V, the tube may produce X-rays that require shielding to protect users from exposure.
• Centering Magnet: A permanent magnet centering magnet (0 to 8 gauss) should extend no more than 2-3/4 inches from the Yoke Reference Line.
• Socket Mounting: The socket must not be mounted rigidly. The associated wiring must be flexible enough to prevent any mechanical strain on the base pins.
• Grounding: The external conductive coating must be reliably grounded to complete the high-voltage filter circuit.

Technical Summary

The 19BFP4 is a 92-degree magnetic deflection, low-voltage electrostatic focus television picture tube featuring a rectangular glass envelope, a 172 sq. in. useful screen area, and a short straight electron gun. Operating at a nominal heater voltage of 6.3 V and a current of 600 mA, it is designed for reliable performance in television receivers. With an anode rating of up to 20,000 V and typical operation at 16,000 V, the tube provides high-brightness displays utilizing its P4 aluminized phosphor screen. Proper circuit design requires grounding the external conductive coating, implementing protective resistance in the grid circuits, and adhering to heater-cathode voltage limits during and after the 11-second warm-up period.