16DP4 — Direct-View Television Picture Tube

The 16DP4 and 16DP4A are direct-view cathode-ray picture tubes designed for television applications. These tubes feature a round glass construction, an indirectly heated unipotential cathode, magnetic focus and deflection systems, and require an external double-field ion trap magnet. They are designed to display a standard television raster size of 10 1/4 inches by 14 1/2 inches.

The two designations are identical in design and electrical characteristics with a single physical exception:

• 16DP4: Features a clear glass faceplate.
• 16DP4A: Features a grey filter faceplate to improve contrast under ambient light.

Mechanical Specifications and Physical Dimensions

The 16DP4 and 16DP4A are large-format glass cathode-ray tubes. Their physical dimensions and mechanical features are precisely defined to ensure proper mounting and alignment within television receivers:

• Overall Length: 20 3/4 ± 1/4 inches
• Greatest Diameter of Bulb: 15 7/8 ± 1/8 inches
• Minimum Useful Screen Diameter: 14 1/2 inches
• Neck Diameter: 1 7/16 ± 1/16 inches
• Bulb Contact: Recessed small cavity cap (designated J1-21)
• Base: Small shell duodecal 5-pin base (designated B5-57)
• Basing Configuration: 12D
• Bulb Contact Alignment: The J1-21 anode contact aligns with the pin position #3 within a tolerance of ±10 degrees.
• Ion Trap Space: A dedicated space of 3 5/8 ± 1/16 inches along the neck must be kept clear for the installation of the external ion trap magnet.

Electrical Characteristics and Basing

Electrical connections are made through the 5-pin duodecal base at the end of the neck, with the high-voltage anode connection made via the recessed cavity cap on the side of the bulb.

Pin Connections (Bottom View)

The 12D basing arrangement provides the following pinout:

Interelectrode Capacitances

The direct interelectrode capacitances of the tube are approximately:

• Cathode to all other electrodes: 5.0 µµF
• Grid No. 1 to all other electrodes: 6.5 µµF

Ratings and Operating Conditions

The operating limits and typical operating points of the 16DP4 and 16DP4A are specified under the Design Center system.

Design Center Maximum Ratings

Typical Operating Conditions

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

• DC Anode Voltage: 12,000 V (Operating anode voltage should not fall below 9,000 V, as brilliance and definition decrease with decreasing anode voltage.)
• DC Grid No. 2 Voltage: 250 V
• DC Grid No. 1 Voltage: -27 V to -63 V (This range represents the limits for visual extinction of the undeflected focused spot.)
• DC Focusing Coil Current: 115 ± 15% mA (This value is approximate and applies when using a standard focus coil No. 109 or equivalent. The distance from the reference line to the center of the air gap on the focus coil is specified as 3.25 inches. This current is determined with the combined Grid No. 1 bias voltage and video signal voltage adjusted to produce a highlight brightness of 20 foot-lamberts on the 10 1/4" by 14 1/2" picture area.)
• DC Ion Trap Current: 109 mA (Approximate, using standard coil No. 108.)

Optical and Screen Characteristics

The screen of the 16DP4 and 16DP4A utilizes a specialized phosphor coating to produce a clear, viewable image:

• Phosphor Number: No. 4
• Fluorescent Color: White
• Phosphorescent Color: White
• Persistence: Medium
• Deflection Angle: Approximately 60 degrees
• Faceplate Light Transmission: The 16DP4A grey filter faceplate has an approximate light transmission of 70 percent at the center, which helps control reflections and enhances contrast in brightly lit environments.

Technical Summary

The 16DP4 and 16DP4A are 16-inch class, round glass, direct-view television picture tubes featuring magnetic focus and deflection with a 60-degree deflection angle. Operating with a nominal 6.3 V, 0.6 A heater, they are designed for high-voltage operation up to a maximum of 15,000 V DC on the anode. They utilize a standard No. 4 white phosphor with medium persistence. The 16DP4 is equipped with a clear glass faceplate, while the 16DP4A incorporates a 70% transmission grey filter faceplate to optimize picture contrast. Both variants employ a small shell duodecal 5-pin base and require an external double-field ion trap magnet for proper operation.