19CFP4 — 19-Inch Rectangular Glass Picture Tube

The 19CFP4 is a 19-inch rectangular glass picture tube (cathode-ray tube) designed for television receiver applications. It features electrostatic focusing and magnetic deflection with a wide 114-degree diagonal deflection angle. The tube incorporates a non-ion trap gun designed specifically for low Grid No. 2 voltage cathode-drive operation. Its screen utilizes an aluminized P4 phosphor on a spherical gray faceplate, providing high-contrast images with approximately 76% light transmittance at the center. An external conductive coating is applied to the bulb, which serves as a high-voltage filter capacitor when properly grounded.

Physical Construction and Screen Characteristics

The 19CFP4 is constructed using a J149-A1 glass bulb envelope. The screen features a spherical gray faceplate with a light transmittance of approximately 76% at the center. The screen is deposited with an aluminized P4 phosphor, which is highly efficient and optimized for television display service.

To facilitate high-voltage connection, the bulb is equipped with a recessed small cavity contact (JETEC No. J1-21) serving as the anode terminal. This anode contact is aligned with Pin No. 4 of the base within a tolerance of ±30 degrees. The tube utilizes either a JETEC No. B7-237 or B7-208 base with an 8HR basing configuration.

An external conductive coating is applied to the envelope. When connected to a system ground, this coating forms a filter capacitor in conjunction with the internal anode coating, helping to smooth the high-voltage anode supply.

Heater and Warm-Up Ratings

The 19CFP4 is equipped with an indirectly heated cathode. The heater is designed for reliable operation under standard television receiver power configurations.

The heater-to-cathode insulation is rated to withstand significant potential differences, which vary depending on the operating state:

• Heater negative with respect to cathode (during warm-up ≤ 15 seconds): 410 V maximum
• Heater negative with respect to cathode (after warm-up): 180 V maximum
• Heater positive with respect to cathode: 180 V maximum

Pinout and Basing (8HR)

The 19CFP4 uses the 8HR basing diagram. The electrical connections, viewed from the bottom of the base, are as follows:

Note that Grid No. 1 is connected to both Pin 2 and Pin 6.

Electrostatic Focus and Magnetic Deflection

The tube employs electrostatic focusing via Grid No. 4 (the focusing electrode) and magnetic deflection to sweep the electron beam across the screen.

• Diagonal Deflection Angle: 114 degrees
• Horizontal Deflection Angle: 102 degrees
• Vertical Deflection Angle: 87 degrees

The electrostatic focusing system is designed to operate at or near ground potential, with typical focus voltages centered around 250 V DC, though individual tubes may focus anywhere within a range of 0 to 500 V DC.

Electrical Characteristics and Interelectrode Capacitances

The direct interelectrode capacitances of the 19CFP4 are relatively low, minimizing loading on the drive circuitry:

• Cathode to all other electrodes: approximately 5 μμF
• Grid No. 1 to all other electrodes: approximately 6 μμF
• External conductive coating to anode: 1000 pF minimum to 1500 pF maximum

Typical Operating Conditions (Cathode-Drive Service)

In typical cathode-drive service, the video signal is applied to the cathode, and Grid No. 1 is maintained at a reference potential. The operating parameters under these conditions are:

Design-Maximum Ratings

The design-maximum rating system defines the limiting receiver design values for the tube. These ratings must not be exceeded under the worst-case operating conditions.

• Anode Voltage: 10,000 V (min) to 17,500 V (max)
• Grid No. 4 (Focusing Electrode) Voltage: -500 V to +1000 V (max)
• Grid No. 2 Voltage: 40 V (min) to 100 V (max)
• Grid No. 1 Voltage:
  • Maximum Negative DC Value: 140 V
  • Maximum Negative Peak Value: 200 V
  • Maximum Positive DC Value: 0 V
  • Maximum Positive Peak Value: 2 V

Circuit Design Constraints and Maximum Values

To ensure reliable operation and prevent damage to the tube's electrodes from internal arcing or transient overloads, specific circuit resistance limits must be observed:

• Maximum Grid No. 1 Circuit Resistance: 1.5 MΩ
• Minimum Grid No. 2 Circuit Resistance: 0.1 MΩ
• Minimum Focusing Electrode (Grid No. 4) Circuit Resistance: 0.1 MΩ

The inclusion of protective series resistance in the Grid No. 2 and focusing electrode circuits is highly advisable to limit surge currents. A single common resistor may be utilized for this protective function where appropriate.

Technical Summary

The 19CFP4 is a 114-degree magnetic deflection, electrostatic-focus 19-inch rectangular picture tube featuring an aluminized P4 phosphor screen and a non-ion trap gun optimized for low Grid No. 2 cathode-drive operation. With a nominal 6.3 V, 600 mA heater and an 11-second warm-up time, it is designed for integration into standard television receiver architectures. The tube operates with typical anode voltages up to 17,500 V and utilizes an external conductive coating to provide high-voltage filtering. Proper circuit design requires adhering to the specified minimum series resistances on Grid No. 2 and Grid No. 4 to protect the electrostatic gun structure.