19DFP4 — Television Picture Tube

The 19DFP4 is a 19-inch diagonal, direct-view rectangular glass television picture tube designed primarily for cathode drive service. It features a 114-degree diagonal deflection angle, electrostatic focusing, and magnetic deflection. As a "HiGm" (high transconductance) tube, it is specifically designed to operate under low Grid #2 voltage conditions. The tube incorporates a spherical faceplate, an aluminized P4 phosphor screen, a non-ion trap gun, internal shielding, and a short tube base with straight-through leads oriented by an indexing lug.

Mechanical and Optical Design

The 19DFP4 is constructed using a rectangular glass envelope with the bulb designation J149A2. The physical dimensions and screen characteristics of the tube are highly standardized for television receiver integration:

• Overall Length: 11-11/16 inches (with a tolerance range of -3/16 to +1/4 inches)
• Neck Length: 4-7/16 inches (with a tolerance range of -1/16 to +1/8 inches)
• Minimum Useful Screen Dimensions: 17-9/16 inches diagonal, 15-1/8 inches width, and 12 inches height, providing a total minimum useful screen area of 172 square inches.
• Anode Contact: A J1-21 button is used for the high-voltage anode connection, aligned with Pin #4 within a tolerance of ±30 degrees.

Optical Characteristics

The screen utilizes an aluminized P4 phosphor that produces a white light output with medium-short persistence. The spherical faceplate is designed to provide approximately 77% light transmission at the center.

Electrical Characteristics and Interelectrode Capacitances

The tube features an indirectly heated cathode with a controlled warm-up time designed for series or parallel heater strings.

• Heater Voltage: 6.3 V
• Heater Current: 0.60 A (with a ±5% tolerance at 6.3 V)
• Heater Warm-up Time: 11 seconds

Direct Interelectrode Capacitances

The capacitive coupling between the tube's internal elements and its external environment is specified as follows:

• Cathode to All Other Electrodes: 4.0 pF
• Grid #1 to All Other Electrodes: 6.0 pF
• External Conductive Coating Capacitance: 1300 pF minimum, 1700 pF maximum

Pinout and Basing Connections

The 19DFP4 utilizes a B7-208 base with an 8HR basing configuration. The short base design employs straight-through leads that are oriented by an indexing lug. The pin connections, viewed from the bottom of the base, are detailed below:

Grid #1 is internally connected to both Pin 2 and Pin 6. Pin 5 is omitted from the active connections.

Cathode Drive Service Ratings and Operating Conditions

The ratings for the 19DFP4 are established under the Design-Maximum system. In cathode drive service, all electrode voltages are specified as positive with respect to Grid #1, unless otherwise noted.

Design-Maximum Ratings

• Anode Voltage: 22,000 V DC maximum
• Grid #4 Voltage (Focusing Electrode): -550 to +1100 V DC
• Grid #2 Voltage: 80 V DC maximum
• Cathode Voltage:
  • Positive-Bias Value: 154 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:
  • Heater negative with respect to cathode (during warm-up ≤ 15 seconds): 450 V maximum
  • Heater negative with respect to cathode (after warm-up): 200 V maximum
  • Heater positive with respect to cathode: 200 V maximum
• Grid #1 Circuit Resistance: 1.5 MΩ maximum

Typical Operating Conditions

Under typical operating conditions in cathode drive service, the tube operates with the following parameters:

• Anode Voltage: 16,000 V DC
• Grid #4 Voltage: -100 to +300 V DC
• Grid #2 Voltage: 65 V DC
• Cathode Voltage (for visual extinction of focused raster): +41 to +56 V DC

For the cutoff of an undeflected focused spot, the absolute bias value increases by approximately 4 V relative to the raster extinction value.

Technical Summary

The 19DFP4 is a 19-inch rectangular glass television picture tube featuring a 114-degree deflection angle, electrostatic focus, and magnetic deflection. Designed for cathode drive service, its "HiGm" gun structure is optimized for low Grid #2 operating voltages (typically 65 V, with an 80 V maximum rating). The tube utilizes an aluminized P4 white phosphor screen with medium-short persistence and a 77% center light transmission. Operating at a typical anode voltage of 16,000 V (up to a maximum of 22,000 V), the 19DFP4 provides a compact, short-neck display solution with a controlled 11-second heater warm-up time and a standardized 8HR basing configuration.