17QP4A — Direct-View Cathode Ray Picture Tube

The 17QP4A is a rectangular glass, direct-view cathode ray picture tube designed for television applications. It features an aluminized screen, which is the primary distinguishing feature separating it from the standard 17QP4. The tube incorporates a grey filter cylindrical faceplate with approximately 66% light transmission at the center to improve contrast. It utilizes magnetic focus and magnetic deflection, a unipotential cathode, and requires an external single-field ion trap.

Mechanical Specifications and Physical Dimensions

The 17QP4A is constructed with a rectangular glass envelope. Its physical dimensions and screen characteristics are as follows:

• Overall Length: 19 3/16 ± 3/8 inches
• Greatest Bulb Dimensions:
  • Diagonal: 16 5/8 ± 1/8 inches
  • Width: 15 3/8 ± 1/8 inches
  • Height: 12 1/4 ± 1/8 inches
• Minimum Useful Screen Dimensions:
  • Diagonal: 15 5/16 inches
  • Width: 14 1/4 inches
  • Height: 10 3/4 inches
  • Raster Size: 10 3/4 inches x 14 1/4 inches
• Deflection Angles (Approximate):
  • Horizontal: 65°
  • Vertical: 50°
  • Diagonal: 70°

The tube uses a recessed small cavity cap (J1-21) for the high-voltage anode contact, which aligns with the vacant pin position #6 within ± 30 degrees. The base is a small shell duodecal 5-pin base (B5-57) with a 12N basing arrangement.

Electrical Connections and Pinout

The bottom view of the small shell duodecal 5-pin base (B5-57) reveals the following pin connections:

• Pin 1: Heater
• Pin 2: Grid No. 1
• Pin 10: Grid No. 2
• Pin 11: Cathode
• Pin 12: Heater
• Anode Cap: Grid No. 3, Anode

Interelectrode Capacitances

The approximate interelectrode capacitances of the 17QP4A are:

• Cathode to all other electrodes: 5 µµf
• Grid No. 1 to all other electrodes: 6.5 µµf
• External conductive coating to anode: 750 µµf (minimum) to 1500 µµf (maximum)

Optical and Phosphor Characteristics

The 17QP4A utilizes a sulfide-type Phosphor No. 4. Its optical performance is characterized by:

• Fluorescent Color: White
• Phosphorescent Color: White
• Persistence: Medium
• Faceplate: Cylindrical grey filter with approximately 66% light transmission at the center.

Maximum Ratings (Design Center Values)

The operating limits for the 17QP4A are established under the Design Center system:

• Heater Voltage: 6.3 Volts
• Heater Current: 0.6 Ampere
• Maximum DC Anode & Grid No. 3 Voltage: 18,000 Volts
• Maximum DC Grid No. 2 Voltage: 500 Volts
• Maximum Grid No. 1 Voltage:
  • DC Negative-bias value: 125 Volts
  • DC Positive-bias value: 0 Volts
  • Positive-peak value: 2 Volts
• Maximum DC Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode during warm-up (≤ 15 seconds): 410 Volts
  • Heater negative with respect to cathode after warm-up: 150 Volts
  • Heater positive with respect to cathode: 150 Volts
• Maximum Grid No. 1 Circuit Resistance: 1.5 Megohms

Typical Operating Conditions and Characteristics

For typical television receiver applications, the 17QP4A is operated under the following conditions:

• DC Anode & Grid No. 3 Voltage: 14,000 Volts
• DC Grid No. 2 Voltage: 300 Volts
• DC Grid No. 1 Voltage (for visual extinction of undeflected focused spot): -28 to -72 Volts
• DC Focusing Coil Current (Approximate): 95 mA
  • Note: This current is specified using a standard focus coil #109 or equivalent, with the combined Grid No. 1 bias and video signal adjusted to produce a highlight brightness of 30 foot-lamberts on a 14 1/4" x 10 3/4" picture. The focus coil air gap center is positioned 3.0 inches from the reference line.
• Ion Trap Field Intensity (Approximate): 30 Gausses (using standard single-field coil #111)

Technical Summary

The 17QP4A is a rectangular, direct-view television picture tube featuring magnetic focus, magnetic deflection, and an aluminized screen. Operating with a 6.3 V, 0.6 A heater, it provides a white, medium-persistence display using Phosphor No. 4. With a maximum anode rating of 18,000 V and typical operation at 14,000 V, it delivers high-brightness images on its 15 5/16-inch diagonal useful screen area. The tube requires an external single-field ion trap (typically 30 Gausses) and a standard focusing coil (typically 95 mA) to achieve optimal focus and spot extinction.