19CXP4 — Cathode-Ray Picture Tube

The 19CXP4 is a 19-inch direct-viewed rectangular glass television picture tube designed for cathode-drive operation. It features a low-voltage electrostatic focusing system and a 114-degree magnetic deflection system. The tube incorporates an electron gun that does not require an ion-trap magnet, and its design is optimized for low Grid-No.2 voltage operation.

Construction and Mechanical Specifications

The 19CXP4 is constructed with a rectangular glass envelope (bulb designation J149A) and a gray filterglass faceplate that provides approximately 78% light transmittance. The screen utilizes an aluminized P4-sulfide phosphor, which exhibits white fluorescence and medium-short persistence.

The physical dimensions and mechanical characteristics of the tube are as follows:

• Overall Length: 11 5/8 ± 1/4 inches (11.625 ± 0.250 inches)
• Neck Length: 4 3/8 ± 1/8 inches (4.375 ± 0.125 inches)
• Weight: Approximately 14 lbs
• Minimum Useful Screen Dimensions:
  • Height: 12 inches
  • Width: 15 1/8 to 15 3/8 inches
  • Diagonal: 17 9/16 inches
  • Projected Area: 172 square inches

The tube is equipped with an external conductive coating of the Regular-Band type. The contact area for grounding this coating is located near the Reference Line, which is determined by the plane C-C' of a JEDEC No. 126 Reference Gauge when seated against the bulb. The anode connection is made via a recessed small cavity cap (JEDEC No. J1-21).

Basing and Pinout Configurations

The 19CXP4 uses a special 6-pin base (JEDEC No. B6-214) with a 7FA bottom-view basing designation. The base pin No. 7 aligns with the anode contact within 30 degrees. There are two distinct recorded pinout configurations for the 7FA basing:

Configuration A

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

Configuration B

• Pin 1: Heater
• Pin 2: Cathode
• Pin 3: Grid No. 1
• Pin 4: Grid No. 4 / Focus
• Pin 6: Grid No. 4 / Focus
• Pin 7: Grid No. 2
• Pin 8: Heater
• Cap: Anode (J1-21 contact)

Electrical Characteristics and Capacitances

Heater Ratings

The heater is designed for operation from a nominal 6.3 V supply. The electrical ratings and characteristics of the heater include:

• Heater Voltage: 6.3 V (with a design-maximum range of 5.7 V to 6.9 V)
• Heater Current: 600 mA (0.60 A) ± 5% (or ± 60 mA)
• Average Heater Warm-up Time: 11 seconds

The heater warm-up time is defined as the time required for the heater voltage to reach 80% of its rated value when 4 times the rated voltage is applied in series with an external resistance equal to 3 times the rated voltage divided by the rated current.

Direct Interelectrode Capacitances

The approximate capacitances of the tube electrodes are:

• Cathode to all other electrodes: 5 pF
• Grid No. 1 to all other electrodes: 6 pF
• External conductive coating to anode: 1400 pF minimum, 1900 pF maximum

Maximum Ratings and Operating Conditions

Design-Maximum Ratings

All voltages are specified as positive with respect to Grid No. 1 unless otherwise indicated. The design-maximum limits must not be exceeded under any operating conditions:

• Anode Voltage: 20,000 V DC maximum, 12,000 V DC minimum
• Grid No. 4 (Focusing Electrode) Voltage: -500 to +1100 V DC
• Grid No. 2 Voltage: 55 V DC maximum (with some ratings listing a minimum of 30 V DC)
• Cathode Voltage:
  • Negative bias value: 0 V DC maximum
  • Negative peak value: 2 V maximum
  • Positive bias value: 100 V DC maximum
  • Positive peak value: 140 V to 150 V maximum
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode during equipment warm-up (≤ 15 seconds): 410 V to 450 V maximum
  • Heater negative with respect to cathode after the warm-up period: 180 V to 200 V maximum
  • Heater positive with respect to cathode: 180 V maximum (or 200 V maximum combined AC and DC, with a 100 V maximum DC component)

Typical Operating Conditions (Cathode-Drive Service)

Under typical cathode-drive operating conditions, the electrode voltages (positive with respect to Grid No. 1) are set as follows:

• Anode Voltage: 16,000 V DC
• Grid No. 4 Voltage for Focus: 0 to +400 V DC (or up to 500 V DC)
• Grid No. 2 Voltage: 45 V DC
• Cathode Voltage for Cutoff: 35 to 50 V DC

The cutoff voltage range is specified for the visual extinction of a focused raster. For the visual extinction of a stationary focused spot, the required cathode voltage is approximately 5 V more positive than the raster extinction value.

Circuit Values and Safety Warnings

• Grid No. 1 Circuit Resistance: 1.5 Megohms maximum.
• X-ray Warning: X-ray radiation shielding may be necessary if the tube is operated above the maximum rated anode voltage or 16,000 V, whichever is less.