17BKP4A — Cathode Ray Tube

The 17BKP4A is a direct-view, rectangular glass picture tube designed for television receiver applications. It features electrostatic focusing and magnetic deflection, utilizing a gray filter faceplate and an aluminized screen. The tube is identical to the 17BKP4 except for the addition of this aluminized screen, which improves brightness and contrast.

Construction and Mechanical Specifications

The 17BKP4A is constructed with a rectangular glass bulb, a gray filter faceplate, an external conductive coating, and requires an external single-field ion trap. The physical dimensions of the tube are as follows:

• Overall Length: 15 5/8 ± 3/8 inches
• Greatest Diagonal Dimension: 16 5/8 ± 1/8 inches
• Greatest Width: 15 3/8 ± 1/8 inches
• Greatest Height: 12 9/32 ± 1/8 inches
• Minimum Useful Screen Dimensions: 14 5/16 inches wide by 11 1/8 inches high, producing a nominal raster size of 14 5/16 by 11 1/8 inches.

The tube uses a Small Shell Duodecal 6-Pin base (B6-63) with a 12L basing configuration. The high-voltage anode connection is made via a Recessed Small Cavity Cap (J1-21), which is aligned with pin position #6 within a tolerance of ± 30 degrees.

Heater and Electrical Characteristics

The 17BKP4A contains an indirectly heated cathode with a heater designed for series or parallel operation:

• Heater Voltage: 6.3 Volts
• Heater Current: 0.450 ± 5% Ampere
• Heater Warm-up Time: Approximately 11.0 seconds. This is defined as the time required for the voltage across the heater terminals to rise to 5.0 V in a standard test circuit with an applied voltage of 25 V and a series resistance of 42 ohms.

Direct Interelectrode Capacitances

The approximate direct interelectrode capacitances of the tube are:

• Cathode to all other electrodes: 5 pF (µµF)
• Grid No. 1 to all other electrodes: 6 pF (µµF)
• External conductive coating to anode: 1200 pF (µµF) minimum, 1500 pF (µµF) maximum

Optical and Deflection Characteristics

The faceplate of the tube is made of gray filter glass with an approximate light transmission of 74% at the center.

• Phosphor: P-4 (Sulfide type), which produces a white fluorescence and white phosphorescence with medium persistence.
• Deflection Method: Magnetic deflection, with approximate deflection angles of:
  • Horizontal: 85°
  • Diagonal: 90°
• Focusing Method: Electrostatic focusing, controlled via Grid No. 4.

Design Center System Ratings

The following maximum ratings are established under the Design Center System:

• Maximum DC Anode Voltage: 17,600 Volts
• Maximum DC Grid No. 4 Voltage: -550 to +1100 Volts
• Maximum DC Grid No. 2 Voltage: 550 Volts
• Maximum Grid No. 1 Voltage:
  • DC negative-bias value: 155 Volts
  • DC positive-bias value: 0 Volts
  • Positive-peak value: 2 Volts
• Maximum DC Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode during warm-up (≤ 15 seconds): 450 Volts
  • Heater negative with respect to cathode after warm-up: 200 Volts
  • Heater positive with respect to cathode: 200 Volts
• Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms

Typical Operating Conditions

Under typical operating conditions, the 17BKP4A is configured with the following parameters:

• DC Anode Voltage: 14,000 Volts
• DC Grid No. 4 Voltage: -56 to +310 Volts (adjusted for visual extinction of the focused raster)
• DC Grid No. 2 Voltage: 300 Volts
• DC Grid No. 1 Voltage: -28 to -72 Volts (adjusted for visual extinction of the focused raster)
• DC Ion Trap Magnet: Requires an external single-field ion trap. When using a Standard Coil #117, the typical current is approximately 28 mA, corresponding to a rated magnetic field strength of 31 Gausses.

Pin Connections and Basing (12L)

The bottom view of the Small Shell Duodecal 6-Pin base (B6-63) provides the following pinout connections:

Technical Summary

The 17BKP4A is a specialized television picture tube featuring a rectangular glass envelope, electrostatic focusing, and magnetic deflection. It is distinguished from the 17BKP4 by its aluminized screen, which provides enhanced brightness on its P-4 phosphor faceplate. Operating at a typical anode voltage of 14,000 Volts, the tube utilizes a 6.3 V, 0.450 A heater with a controlled 11-second warm-up time, making it suitable for standard television receiver designs.