16TP4 — Rectangular Glass Cathode-Ray Tube

The 16TP4 is a direct-view, all-glass rectangular picture tube designed for television applications, featuring magnetic focus and deflection, a spherical gray filter faceplate, and an external conductive coating.

Overview

The 16TP4 is a 16-inch rectangular cathode-ray tube designed primarily for television receiver service. It features an all-glass construction with a space-saving rectangular face shape that provides a nominal raster size of 13 1/2 inches by 10 1/8 inches. The tube utilizes magnetic deflection and magnetic focusing, requiring an external single-field ion-trap magnet to prevent ion burn on the phosphor screen.

To enhance picture quality, the 16TP4 incorporates a spherical gray filter faceplate that improves contrast and detail under high-ambient-light conditions. Additionally, an external conductive coating is applied to the bulb cone, which acts as a high-voltage filter capacitor when connected to ground.

Mechanical Specifications and Optical Characteristics

The 16TP4 is constructed with a rectangular glass envelope and has the following physical dimensions:

The minimum useful screen dimensions are 14 7/8 inches diagonally, 13 1/2 inches in width, and 10 1/8 inches in height. The bulb number carries the ASA designation J129-B1.

Optical Data

The tube's screen uses a P4 sulfide-type phosphor, which produces a white fluorescent and phosphorescent color with a short persistence. The spherical gray faceplate has an approximate light transmission of 72 percent at the center, which helps maintain picture contrast by reducing reflections and ambient light glare.

Electrical Connections and Basing

The 16TP4 is equipped with a unipotential cathode and a standard heater. The electrical connections are made through a base at the end of the neck and a high-voltage recessed small cavity cap on the side of the bulb.

• Base: Small-shell Duodecal (B5-57), available in 5-pin or 15-pin configurations.
• Basing Designation: 12N.
• Anode Contact: Recessed small cavity cap (J1-21).
• Bulb Contact Alignment: The J1-21 anode contact aligns with pin position No. 6 ± 30 degrees.

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

Grid No. 3 and the anode are connected together internally and are brought out to the recessed small cavity cap on the bulb cone.

Interelectrode Capacitances

The direct interelectrode capacitances of the 16TP4 are approximately:

• Cathode to all other electrodes: 5 µµf
• Grid No. 1 to all other electrodes: 6 µµf
• External conductive coating to anode (Maximum): 2000 µµf
• External conductive coating to anode (Minimum): 750 µµf

The external conductive coating must be grounded to utilize its capacitance as a high-voltage filter.

Typical Operating Conditions and Characteristics

The 16TP4 operates with high anode voltages to ensure adequate brightness and focus quality. In general, the anode voltage should not be operated below 10,000 volts, as performance degrades at lower potentials.

The typical operating parameters under standard conditions are:

Focusing and Deflection Requirements

The deflection system is magnetic, providing approximate deflection angles of:

• Diagonal: 70 degrees
• Horizontal: 65 to 66 degrees
• Vertical: 50 degrees

Focusing is achieved magnetically using a standard focusing coil (such as JETEC No. 109 or equivalent). For proper focus, the distance from the yoke-reference-line to the center of the air gap on the focus coil must be maintained at 3 1/8 inches. The combined Grid No. 1 bias and video signal are typically adjusted to produce a highlight brightness of 35 foot-lamberts on a standard 10 1/8" by 13 1/2" picture.

The electron gun requires an external single-field ion-trap magnet (such as JETEC No. 117 or equivalent) adjusted to its optimum position. This corresponds to an approximate field intensity of 35 Gausses, or a current of 75 ± 50% mA through a standard No. 111 coil. The space on the neck designated for the ion-trap magnet must be kept clear of other magnetic components.

Maximum Ratings and Circuit Limits

The following maximum ratings are established under the Design-Center system, which incorporates a ten-percent safety factor to accommodate variations in line voltage and component tolerances:

Peak Heater-Cathode Voltage Limits

The cathode should be returned to one side or to the center tap of the heater transformer winding. The maximum peak heater-cathode voltages are:

• Heater negative with respect to cathode:
  • During warm-up period (not to exceed 15 seconds): 410 Volts
  • After equipment warm-up period: 150 Volts
• Heater positive with respect to cathode: 150 Volts

Technical Summary

The 16TP4 is a 16-inch rectangular, all-glass cathode-ray tube designed for direct-view television applications. It features a 6.3 V, 0.6 A heater (with a ±10% current tolerance), a unipotential cathode, and a 12N duodecal basing configuration. Utilizing magnetic focus and deflection with a 70-degree diagonal deflection angle, the tube is optimized for operation at an anode voltage of 12,000 V (with a design-center maximum of 14,000 V). Its spherical gray filter faceplate provides a high-contrast white image (P4 phosphor) with short persistence, while its external conductive coating provides integrated high-voltage filtering when grounded.