17KP4 — Electrostatic-Focus Television Picture Tube

Overview

The 17KP4 is a direct-view cathode-ray picture tube designed for television applications. It features a rectangular glass construction with a nominal diagonal dimension of 16 5/8 inches. The tube utilizes electrostatic focusing and magnetic deflection, incorporating a grey filter faceplate to enhance picture contrast under ambient light. To ensure proper beam alignment and operation, the 17KP4 requires an external single-field ion trap and an external conductive coating.

Mechanical Specifications and Optical Characteristics

The 17KP4 is constructed with a rectangular glass envelope. Its physical dimensions and screen area are highly standardized for television receiver integration:

• Overall Length: 19 1/4 ± 3/8 inches
• Greatest Bulb Dimensions:
  • Diagonal: 16 5/8 ± 1/8 inches
  • Width: 15 3/8 ± 1/8 inches
  • Height: 12 1/4 ± 1/8 inches
• Minimum Useful Screen Dimensions:
  • Width: 14 1/4 inches
  • Height: 10 3/4 inches
  • Raster Size: 14 1/8" x 10 3/4" to 14 1/4" x 10 3/4"

The faceplate is made of grey filter glass with a light transmission of approximately 66% at the center. The screen is coated with Phosphor No. 4, which produces a white fluorescent and white phosphorescent color with medium persistence, suitable for television scanning rates.

The deflection system is designed for magnetic deflection with approximate deflection angles of:

• Horizontal: 65 degrees
• Diagonal: 70 degrees

Electrical Connections and Basing

The tube uses a small shell duodecal 5-pin base (B5-57) with a 12P basing designation. High voltage is applied to the anode via a recessed small cavity cap (J1-21). The anode contact is aligned with pin position #6 within a tolerance of ±30 degrees.

The pin connections, viewed from the bottom of the base, are as follows:

• Pin 1: Heater
• Pin 2: Grid No. 1
• Pin 10: Grid No. 2
• Pin 11: Cathode
• Pin 12: Heater
• Anode Cap: Recessed small cavity cap (J1-21)

Interelectrode Capacitances

The direct interelectrode capacitances of the 17KP4 are approximately:

• Cathode to all other electrodes: 6.0 μμf
• Grid No. 1 to all other electrodes: 6.5 μμf
• External conductive coating to anode: 1,000 μμf (minimum) to 1,500 μμf (maximum)

The external conductive coating forms a capacitor with the internal anode coating, which can be utilized as a high-voltage filter capacitor in the receiver's power supply circuit.

Heater and Maximum Ratings

The 17KP4 operates with an indirectly heated unipotential cathode. The heater ratings and absolute design-center maximum limits are specified to ensure reliable operation:

Heater Ratings

• Heater Voltage: 6.3 Volts
• Heater Current: 0.6 Ampere

Design-Center Maximum Ratings

• Maximum DC Anode Voltage: 16,000 Volts
• Maximum DC Grid No. 2 Voltage: 500 Volts
• Maximum Grid No. 1 Voltage:
  • DC Negative-Bias Value: 125 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): 410 Volts
  • Heater negative with respect to cathode (after warm-up): 180 Volts
  • Heater positive with respect to cathode: 180 Volts

The maximum grid No. 1 circuit resistance must not exceed 1.5 Megohms.

Typical Operating Conditions

Under typical operating conditions, the 17KP4 is configured with the following electrical and magnetic parameters:

• DC Anode Voltage: 12,000 Volts
• DC Grid No. 2 Voltage: 300 Volts
• DC Grid No. 1 Voltage (for visual extinction of undeflected focused spot): -33 to -77 Volts
• DC Ion Trap Current (using Standard Coil #111): 50 ± 50% mA (approximately)
• Field Strength of Centering Magnet: 0 to 8 Gausses

The electrostatic focusing mechanism operates in conjunction with the magnetic deflection coils and the external centering magnet to produce a sharp, well-defined raster. The external single-field ion trap magnet must be adjusted to prevent ion burn on the phosphor screen.

Technical Summary

The 17KP4 is a rectangular, electrostatic-focus, magnetic-deflection television picture tube featuring a 16 5/8-inch diagonal screen. It utilizes a unipotential cathode with a standard 6.3 V, 0.6 A heater. Operating typically at an anode potential of 12,000 V and a grid No. 2 potential of 300 V, it provides a medium-persistence white display using Phosphor No. 4. The tube is housed in a glass envelope with a 12P duodecal base and a recessed small cavity cap for the high-voltage anode connection.