17CRP4 — Direct-View Picture Tube

The 17CRP4 is a 17-inch diagonal, direct-view cathode-ray tube (CRT) designed specifically for cathode-drive television applications. Engineered for series string operation, it features a 90-degree diagonal deflection angle and an 85-degree horizontal deflection angle. The tube utilizes electrostatic focusing combined with magnetic deflection.

Construction and Optical Characteristics

The 17CRP4 is constructed with a spherical gray filter glass faceplate that provides approximately 74% light transmission. Its screen is metal-backed (aluminized) and uses P4 phosphor, which produces a white fluorescence with medium persistence.

Designed with a short overall length, the tube does not require an external ion trap magnet. It incorporates a high-capacity external conductive coating that serves as a filter capacitor and aids in suppressing radiation when properly grounded.

Mechanical Dimensions

• Overall Length: 14-5/8 ± 3/8 inches
• Neck Length: 5-1/2 ± 3/16 inches
• Greatest Bulb Diagonal: 16-5/8 ± 1/8 inches
• Greatest Bulb Width: 15-3/8 ± 1/8 inches
• Greatest Bulb Height: 12-9/32 ± 1/8 inches
• Minimum Useful Screen Dimensions: 11-1/8 x 14-5/16 inches, yielding a minimum useful screen area of 149 square inches.

Electrical Data and Basing

The 17CRP4 is equipped with a small shell Duodecal 6-pin base (B6-63) with a 12L basing designation. The final anode connection is made via a recessed small cavity cap (J1-21), which aligns with Pin Position No. 6 within a tolerance of ± 30 degrees.

Pinout Configuration

• Pin 1: Heater
• Pin 2: Grid No. 4 (Focusing Electrode)
• Pin 6: Grid No. 1
• Pin 10: Grid No. 2
• Pin 11: Cathode
• Pin 12: Heater
• Recessed Cavity Cap: Final Anode (internally connecting Grid No. 3, Grid No. 5, and the Collector)

Heater Specifications

• Heater Voltage: 6.3 V
• Heater Current: 0.450 ± 5% A
• Heater Warm-up Time: 11 seconds (defined as the time required for the heater voltage to reach 5.0 V in a JETEC test circuit with an applied voltage of 25 V and a series resistance of 42 ohms)

Direct Interelectrode Capacitances

• Cathode to all other electrodes: approximately 5 µµF
• Grid No. 1 to all other electrodes: approximately 6 µµF
• External conductive coating to anode: 1800 µµF minimum to 2300 µµF maximum

Absolute Maximum Ratings

The following absolute maximum limits are established for the 17CRP4:

• Final Anode Voltage: 17,600 V dc
• Grid No. 4 Voltage (Focusing Electrode): −550 to +1,100 V dc
• Grid No. 2 to Grid No. 1 Voltage: 70 V dc
• Cathode to Grid No. 1 Voltage (Positive bias value): 150 V dc
• Cathode to Grid No. 1 Voltage (Negative peak value): 0 V
• Peak Heater-Cathode Voltage (During warm-up, ≤ 15 seconds): 450 V
• Peak Heater-Cathode Voltage (After warm-up): 200 V
• Heater Positive with Respect to Cathode: 200 V

Typical Operating Conditions (Cathode Drive)

Under typical cathode-drive operating conditions, the tube is configured as follows:

• Anode Voltage: 14,000 V dc
• Grid No. 2 to Grid No. 1 Voltage: 50 V dc
• Grid No. 4 to Grid No. 1 Voltage for Focus (at 100 µA cathode current): 0 to +350 V dc
• Cathode to Grid No. 1 Voltage for Cut-off (visual extinction of focused raster): 30 to 50 V dc

When operated in cathode drive at a Grid No. 2 voltage of 50 V, the tube exhibits a maximum spot cut-off of 50 V and a minimum cathode current of 1000 µA.

Operating and Circuit Considerations

• Grid No. 1 Circuit Resistance: The maximum allowable resistance in the Grid No. 1 circuit is 1.5 Megohms.
• External Coating Grounding: The high-capacity external conductive coating must be grounded to function as a filter capacitor and to suppress radiation.
• Focus Modulation: The focus electrode (Grid No. 4) may be modulated to improve overall focus across the screen.
• Raster vs. Spot Extinction: Visual extinction of a stationary focused spot requires cut-off values to be increased by approximately 5 V compared to the visual extinction of a focused raster.
• Cut-off Voltage Variation: The cut-off voltage varies dynamically with anode voltage, changing by approximately 2% for every 1 kV change in the anode voltage.

Technical Summary

The 17CRP4 is a 17-inch, 90-degree deflection, electrostatic-focus, magnetic-deflection picture tube designed for series-string cathode-drive television receivers. It features a short neck and overall length, an aluminized P4 screen, and a high-capacity external conductive coating. Operating at a typical anode voltage of 14,000 V, it provides reliable focus and cut-off characteristics with a controlled 11-second heater warm-up time.