17BRP4 — Electrostatic-Focus Magnetic-Deflection Picture Tube

The 17BRP4 is a 17-inch rectangular glass, direct-view cathode-ray picture tube designed for television receiver applications. It features electrostatic focusing, magnetic deflection, a short overall length, and a small neck diameter. The design incorporates an aluminized fluorescent screen, an ion-trap gun requiring an external magnet, and an external conductive coating that serves as a high-voltage filter capacitor when grounded.

Mechanical and Optical Specifications

The 17BRP4 is constructed with a rectangular glass envelope and a spherical gray faceplate. The faceplate glass provides approximately 76% light transmission at the center, improving picture contrast under ambient light.

Physical Dimensions and Weight

• Overall Length: 12 9/16 ± 5/16 inches
• Neck Length: 5 7/16 + 3/16 - 1/8 inches
• Bulb Dimensions:
  • Diagonal: 16 9/16 ± 0.100 inches
  • Width: 15 5/8 ± 0.100 inches
  • Height: 12 3/4 ± 0.100 inches
• Minimum Useful Screen Dimensions:
  • Diagonal: 15 3/4 inches
  • Width: 14 3/4 inches
  • Height: 11 11/16 inches
  • Total Area: 155 square inches
• Net Weight: Approximately 10 1/3 lbs
• Mounting Position: Any

Optical Characteristics

The tube utilizes a P4 sulfide-type phosphor screen, which produces white fluorescence and phosphorescence with short persistence. The aluminized backing on the screen increases light output and prevents ion burn in conjunction with the ion-trap gun.

Deflection Angles

The tube is designed for wide-angle magnetic deflection with the following approximate angles:

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

Electrical Connections and Pinout

The 17BRP4 uses a Small-button Eightar 7-pin base (JETEC No. B7-183) with an 8HR basing designation. High voltage is applied to the anode via a recessed small-cavity cap (JETEC No. J1-21) located on the bulb. The anode contact is aligned with Pin No. 4 within a tolerance of ±30 degrees.

Pin Assignment (8HR Diagram)

• Pin 1: Heater
• Pin 2: Grid No. 1
• Pin 3: Grid No. 2
• Pin 4: Focusing Electrode (Grid No. 4)
• Pin 6: Grid No. 1
• Pin 7: Cathode
• Pin 8: Heater
• Recessed Cap: Anode (Grid No. 3 and Grid No. 5 are connected internally to the anode)

Heater Ratings

The heater is designed for series or parallel operation with the following nominal ratings:

• Heater Voltage: 6.3 V
• Heater Current: 0.6 A ± 10%
• Heater Warm-up Time: 11 seconds (measured in a standard test circuit with an applied voltage of 25 V and a series resistance of 31.5 ohms)

Interelectrode Capacitances

• Cathode to all other electrodes: 5 µµF (approximate)
• Grid No. 1 to all other electrodes: 6 µµF (approximate)
• External conductive coating to anode: 800 µµF (minimum) to 1400 µµF (maximum)

Operating Ratings and Typical Conditions

The ratings of the 17BRP4 are established under the Design-Center System. Operating the tube within these limits ensures reliable performance and longevity.

Absolute Maximum Ratings

• Anode Voltage: 15,000 Max V DC
• Focusing-Electrode Voltage: -500 to +1000 Max V DC
• Grid-No. 2 Voltage: 500 Max V DC
• Grid-No. 1 Voltage:
  • Negative-Bias Value: 140 Max V DC
  • Positive-Bias Value: 0 Max V DC
  • Positive-Peak Value: 2 Max V
  • Negative-Peak Value: 200 Max V
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode (during warm-up ≤ 15 seconds): 410 Max V
  • Heater negative with respect to cathode (after warm-up): 180 Max V
  • Heater positive with respect to cathode: 180 Max V

Typical Operating Conditions

For standard operation, the following parameters represent typical performance points:

• Anode Voltage: 14,000 V DC (minimum recommended operating voltage is 12,000 V)
• Focusing-Electrode Voltage for Focus: 0 to 500 V DC
• Focusing-Electrode Current: -15 to +25 µA DC
• Grid-No. 2 Voltage: 300 V DC
• Grid-No. 1 Voltage (for visual extinction of focused raster): -28 to -72 V DC
• Ion-Trap Field Intensity: 37 Gausses minimum (using a Heppner PM ion-trap magnet or equivalent adjusted to the optimum position)

Maximum Circuit Values

To protect the tube from damage due to internal arcing or excessive current, specific circuit resistance limits must be observed:

• Grid-No. 1 Circuit Resistance: 1.5 Max Megohms
• Grid-No. 2 Circuit Resistance: 0.1 Min Megohms
• Focusing-Electrode Circuit Resistance: 0.1 Min Megohms

Note: It is highly recommended to include protective resistance in both the Grid-No. 2 and the focusing-electrode circuits to safeguard the gun structure.

Technical Summary

The 17BRP4 is a compact, wide-angle (110° diagonal) television picture tube featuring electrostatic focus and magnetic deflection. Utilizing a 17-inch rectangular glass envelope with a short overall length of 12 9/16 inches, it is optimized for space-saving chassis designs. The tube operates typically at an anode voltage of 14,000 V DC, requiring an external ion-trap magnet of at least 37 Gausses and a 6.3 V, 0.6 A heater supply. Its integrated external conductive coating provides essential high-voltage filtering when properly integrated into the receiver circuitry.