17HP4 — Direct-View Cathode Ray Tube

A rectangular glass, electrostatic-focus, magnetic-deflection picture tube designed for television applications.

Overview

The 17HP4 is a direct-view cathode ray tube (CRT) designed primarily for television receiver applications. It features a rectangular glass construction, a unipotential cathode, electrostatic focusing, and magnetic deflection. The tube incorporates an external conductive coating and requires an external single-field ion trap for proper operation.

The 17HP4 family includes three variants that share identical electrical and mechanical characteristics, differing only in their faceplate and screen treatments:

• 17HP4: The base model, featuring a grey filter faceplate.
• 17HP4A: A variant featuring a grey frosted filter faceplate.
• 17HP4B: A variant featuring an aluminized screen.

The tube provides a nominal raster size of approximately 10 3/4 inches by 14 1/8 to 14 1/4 inches, offering a compact yet highly readable display area for standard television designs.

Mechanical Specifications and Physical Dimensions

The 17HP4 is constructed with a rectangular glass bulb and a small shell duodecal 6-pin base (B6-63). Its physical dimensions and mechanical tolerances are tightly defined:

• Overall Length: 19 3/16 ± 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 5/16 inches
  • Height: 10 3/4 inches

The high-voltage anode connection is made via a recessed small cavity cap (J1-21) located on the bulb cone. This contact is aligned with pin position #6 on the base within a tolerance of ± 30 degrees.

Electrical Connections and Pinout

The 17HP4 utilizes a 12L basing arrangement, viewed from the bottom of the tube. The electrical connections are distributed across the 6-pin duodecal base and the recessed anode cavity cap as follows:

Heater Ratings

The unipotential cathode is indirectly heated by a filament designed for standard television receiver power supplies:

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

Interelectrode Capacitances

The direct interelectrode capacitances of the tube are approximately:

• Cathode to all other electrodes: 5 μμF
• Grid No. 1 to all other electrodes: 6 μμF
• External conductive coating to anode:
  • Maximum: 1,500 μμF
  • Minimum: 750 μμF

The external conductive coating acts as a capacitor in conjunction with the internal anode coating, which can be utilized for high-voltage ripple filtering in the receiver's power supply.

Optical and Deflection Characteristics

The 17HP4 utilizes a standard phosphor screen and specific deflection angles to achieve its display geometry:

• Phosphor: No. 4, which produces a white fluorescent and white phosphorescent color with medium persistence.
• Faceplate Light Transmission: Approximately 66% at the center of the screen (specifically documented for the base 17HP4 model).
• Deflection Angles (Approximate):
  • Horizontal: 65 degrees
  • Diagonal: 70 degrees

These deflection angles dictate the scanning power and yoke design required to fully sweep the raster across the screen surface.

Operating Conditions and Design Center Ratings

The operating parameters of the 17HP4 are divided into typical operating conditions and absolute design center ratings. Designers must ensure that the maximum limits are not exceeded under worst-case line voltage and component tolerance conditions.

Design Center Ratings

• Grid No. 3, Grid No. 5, Collector Voltage (Anode): 16,000 Volts DC maximum
• Grid No. 4 Voltage: 500 Volts DC maximum
• Grid No. 2 Voltage: 500 Volts DC maximum
• Grid No. 1 Voltage:
  • DC Negative-Bias Value: 125 Volts maximum
  • DC Positive-Bias Value: 0 Volts maximum
  • Positive-Peak Value: 2 Volts maximum
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode during warm-up (not to exceed 15 seconds): 410 Volts maximum
  • Heater negative with respect to cathode after warm-up: 180 Volts maximum
  • Heater positive with respect to cathode: 180 Volts maximum
• Grid No. 1 Circuit Resistance: 1.5 Megohms maximum

Typical Operating Conditions

Under typical operating conditions, the tube is set up with the following electrode potentials:

• Grid No. 3, Grid No. 5, Collector Voltage: 14,000 Volts DC
• Grid No. 4 Voltage: -56 to +310 Volts DC (for focusing)
• 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: Approximately 85 mA when using a Standard Coil No. 111.

The wide range of Grid No. 4 voltage (-56 to +310 Volts) allows for precise electrostatic focusing adjustment across individual production variations of the tube. The ion trap current of 85 mA is required to align the electron beam through the gun structure, preventing ion burn on the phosphor screen.

Technical Summary

The 17HP4 is a versatile rectangular glass cathode ray tube featuring electrostatic focus and magnetic deflection (65° horizontal, 70° diagonal). Operating with a 6.3 V, 0.6 A heater, it delivers a high-resolution monochrome display using No. 4 white phosphor with a medium persistence characteristic. The tube is supported by variants 17HP4A (frosted faceplate) and 17HP4B (aluminized screen) to suit different cabinet and lighting environments. With a maximum anode rating of 16,000 V and a typical operating anode voltage of 14,000 V, it provides a reliable, bright, and sharp display for television receivers of its era.