17CWP4 — Electrostatic-Focus Magnetic-Deflection Picture Tube

The 17CWP4 is an all-glass, rectangular, direct-view cathode-ray picture tube designed for television receiver applications. It features electrostatic focusing and magnetic deflection, utilizing a short electron gun that eliminates the need for an external ion-trap magnet. The tube incorporates a wide-angle deflection system and a spherical filter-glass faceplate to optimize picture quality and minimize cabinet depth.

Mechanical Design and Physical Dimensions

The 17CWP4 is constructed with an all-glass rectangular envelope designated as bulb number J132 1/2 A1. It features a spherical faceplate made of neutral-density filter glass, which provides a light transmission of approximately 77% to improve picture contrast under ambient light.

The tube has a short 1-1/2" neck, which is made possible by its compact, straight-type electrostatic gun. The overall mechanical specifications are as follows:

• Overall Length: 11-5/8" ± 5/16"
• Greatest Bulb Dimensions:
  • Diagonal: 16-9/16" ± 1/8"
  • Width: 15-5/8" ± 1/8"
  • Height: 12-3/4" ± 1/8"
• Minimum Useful Screen Dimensions (Maximum Assured):
  • Screen Area: 155 sq. in.
  • Diagonal: 15-3/4"
  • Width: 14-3/4"
  • Height: 11-11/16"
• Weight: 10 lbs.

The tube uses a B7-183 base and an 8-pin 8HR basing arrangement. High-voltage connection to the anode is made via a J1-21 bulb contact. This contact is aligned with pin position #4 within a tolerance of ± 30°.

Electron Gun, Deflection, and Basing

The 17CWP4 employs a straight-type electron gun that does not require an ion trap. It uses electrostatic focusing, where Grid No. 4 serves as the focus electrode, and magnetic deflection. The deflection angles of the system are:

• Diagonal Deflection: 110°
• Horizontal Deflection: 105°
• Vertical Deflection: 87°

The phosphor screen is designated as P4, which produces a white fluorescence with short-to-medium persistence. The tube's external surface is coated with a conductive layer that forms a capacitor with the internal anode coating.

Pinout Configuration (8HR Basing)

The electrical connections are made through the B7-183 base pins, viewed from the bottom of the tube:

Electrical Characteristics and Capacitances

The direct interelectrode capacitances of the 17CWP4 are approximately:

• Cathode to all other electrodes: 5 µµF
• Grid No. 1 to all other electrodes: 6 µµF
• External conductive coating to anode: 1000 pF (minimum) to 1500 pF (maximum) (expressed as 1000 min. µµF to 1500 max. µµF)

The external conductive coating must be grounded to serve as an effective filter capacitor for the high-voltage anode supply.

Maximum Ratings (Design Center Values)

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

• Heater Voltage: 6.3 V
• Heater Current: 0.6 A
• Anode Voltage: 16,000 V
• Grid No. 4 Voltage (Focus Electrode): -500 V to +1,000 V
• Grid No. 2 Voltage: 500 V
• Grid No. 1 Voltage:
  • Negative Peak Value: 200 max. V
  • Negative Bias Value: 140 max. V
  • Positive Bias Value: 0 max. V
  • Positive Peak Value: 2 max. V
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode during warm-up (≤ 15 s): 410 V
  • Heater negative with respect to cathode after warm-up: 180 V
  • Heater positive with respect to cathode: 180 V
• Grid No. 1 Circuit Resistance: 1.5 max. MΩ

Typical Operating Conditions

Under typical operating conditions, the 17CWP4 is operated with the following electrode potentials:

• Anode Voltage: 14,000 V
• Grid No. 2 Voltage: 400 V
• Grid No. 1 Voltage (for visual extinction of focused raster): -36 V to -92 V
• Grid No. 4 Voltage (Focus Electrode): -50 V to +350 V

The focus electrode voltage range of -50 V to +350 V is specified with the combined Grid No. 1 bias and video signal adjusted to produce an anode current of 100 µA on an 11-11/16" x 14-3/4" picture.

Focus Voltage Calculation

For anode voltages other than the typical 14,000 V, the required focus voltage scales relative to the anode potential. The focus voltage is calculated to be within -0.4% to +2.5% of the operating anode voltage.

For example, at the typical anode voltage of 14,000 V:

• Minimum Focus Voltage: 14,000 V * (-0.004) = -56 V
• Maximum Focus Voltage: 14,000 V * 0.025 = +350 V

These calculated limits closely align with the typical specified range of -50 V to +350 V.

Technical Summary

The 17CWP4 is a 110° magnetic-deflection, electrostatic-focus picture tube featuring a space-saving short neck and a straight-type electron gun. Operating at a typical anode voltage of 14,000 V (with a design center maximum of 16,000 V), it provides a 155-square-inch useful screen area on a P4 white phosphor faceplate. Its electrostatic focus electrode (Grid No. 4) operates typically between -50 V and +350 V, scaling dynamically as -0.4% to +2.5% of the anode voltage. The tube's design center ratings, standard 6.3 V heater, and 8HR basing make it a highly integrated display component for compact television chassis designs.