17BVP4 — Electrostatic-Focus Television Picture Tube

Overview

The 17BVP4 is a very short, lightweight, direct-view television picture tube featuring a 17-inch rectangular glass envelope. It is designed with an aluminized screen, a gray filter faceplate, and a unipotential cathode. The tube utilizes electrostatic focusing and magnetic deflection, with a wide deflection angle design (110° diagonal) to minimize overall length. Additional features include an external conductive coating that must be grounded, an external single-field ion trap, and a controlled heater warm-up time.

Mechanical and Physical Construction

The 17BVP4 is constructed with a rectangular glass bulb (J132 1/2 A1) and has a nominal neck diameter of 1 1/8 inches. The tube's physical dimensions are optimized for compact television receiver cabinets, featuring an overall length of 13 1/4 ± 5/16 inches.

The external dimensions of the bulb are:

• Greatest Diagonal: 16.562 ± 0.100 inches
• Greatest Width: 15.625 ± 0.100 inches
• Greatest Height: 12.750 ± 0.100 inches

The screen provides a minimum useful area of 155 square inches, with the following minimum useful dimensions:

• Diagonal: 15.750 inches
• Width: 14.750 inches (also listed as 14 3/4 inches)
• Height: 11.750 inches (also listed as 11 11/16 or 11 3/4 inches)

The faceplate is a spherical gray filter glass with approximately 79% light transmission at the center, which improves picture contrast under ambient room lighting. The tube weighs approximately 10 lbs.

The electrical connection to the high-voltage anode (Grid No. 3) is made via a recessed small cavity cap (J1-21) located on the bulb cone. The tube uses a B6-185 base with a 7FA basing configuration. The J1-21 anode contact is aligned with base pin position No. 7 within a tolerance of ±30 degrees.

Heater and Warm-Up Characteristics

The 17BVP4 features a controlled heater warm-up time, making it suitable for series-string heater arrangements or standard parallel operation.

The controlled warm-up time of 11.0 seconds is defined as the time required for the heater terminal voltage to increase to 5.0 V when measured in a standard test circuit with an applied voltage of 25 V and a series resistance of 31.5 Ω.

Base Connections and Pinout

The 17BVP4 uses the 7FA basing arrangement. Depending on the specific production design, two distinct heater pin configurations are documented:

• Configuration A: Heater connections on Pin 3 and Pin 4.
• Configuration B: Heater connections on Pin 1 and Pin 8.

The remaining pin connections are consistent across configurations:

• Pin 2: Cathode
• Pin 5: Grid No. 1 (Control Grid)
• Pin 6: Grid No. 4 (Focusing Electrode)
• Pin 7: Grid No. 2 (Screen Grid)
• Anode Cap (J1-21): Grid No. 3 (Anode)

Optical and Deflection Characteristics

The tube utilizes a sulfide-type P-4 phosphor screen, which is aluminized to increase light output and prevent ion burn.

• Fluorescent Color: White
• Phosphorescent Color: White
• Persistence: Short to Medium

Deflection is accomplished magnetically, with wide deflection angles to support the short neck and shallow cabinet depth:

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

An external, single-field permanent magnet ion trap is required to prevent ion damage to the screen. The rated strength of the ion trap magnet is 33 Gausses (with a typical tolerance of ±3 gausses).

Electrical Ratings and Operating Conditions

The ratings of the 17BVP4 are established under the Design Center System. Operating the tube beyond these limits may impair performance or cause permanent damage.

Absolute Maximum Ratings

• Anode Voltage (Grid No. 3): 17,600 V DC
• Grid No. 4 Voltage (Focusing Electrode): -550 to +1100 V DC
• Grid No. 2 Voltage: 550 V DC
• Grid No. 1 Voltage:
  • DC Negative-Bias Value: 154 V DC
  • Negative Peak Value: 220 V
  • DC Positive-Bias Value: 0 V DC
  • Positive-Peak Value: 2 V
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode (during warm-up period ≤ 15 seconds): 450 V
  • Heater negative with respect to cathode (after equipment warm-up): 200 V
  • Heater positive with respect to cathode: 200 V
• Grid No. 1 Circuit Resistance: 1.5 MΩ Max.

Typical Operating Conditions

Under typical operating conditions, the focusing electrode (Grid No. 4) is adjusted to obtain the sharpest focus across the raster.

• DC Anode Voltage: 14,000 V
• DC Grid No. 4 Voltage: -50 to +350 V
• DC Grid No. 2 Voltage: 300 V
• DC Grid No. 1 Voltage (for visual extinction of focused raster): -35 to -72 V
  • Note: Visual extinction of a stationary focused spot requires approximately 5 V more negative bias than raster extinction.

Direct Interelectrode Capacitances

• Cathode to all other electrodes: 5 µµF (approx.)
• Grid No. 1 to all other electrodes: 6 µµF (approx.)
• External conductive coating to Anode: 1000 µµF (Min) to 1500 µµF (Max)
  • Note: The external conductive coating must be grounded, as it forms a high-voltage filter capacitor in conjunction with the internal anode coating.

Safety and Radiation Considerations

When operating the 17BVP4, safety precautions regarding X-ray radiation must be observed. If the tube is operated at anode voltages exceeding 16,000 V, or above the maximum rated anode voltage of 17,600 V (whichever is lower), shielding may be necessary to protect personnel against prolonged, close-range exposure to X-rays.

Technical Summary

The 17BVP4 is a 17-inch rectangular, electrostatic-focus, magnetic-deflection television picture tube. It features a short-neck design with a 110° diagonal deflection angle, an aluminized P-4 screen with white fluorescence and phosphorescence, and a gray filter faceplate with 79% light transmission. Operating at a typical anode voltage of 14,000 V, the tube provides a minimum useful screen area of 155 square inches. Its controlled 11.0-second heater warm-up time makes it suitable for series-string receiver designs. The tube is housed in a J132 1/2 A1 bulb with a B6-185 base and a 7FA basing configuration, utilizing either pins 3 and 4 or pins 1 and 8 for its 6.3 V, 0.6 A heater.