17LP4A Cathode Ray Picture Tube

The 17LP4A is a direct-view rectangular glass cathode ray picture tube designed for television applications. It features a cylindrical faceplate, a grey filter faceplate, and an external conductive coating. A key distinguishing feature of the 17LP4A is its aluminized screen. The tube utilizes magnetic deflection and low-voltage electrostatic focusing, along with an external single-field ion trap.

Mechanical and Optical Design

The 17LP4A is constructed with a rectangular glass bulb and has the following physical dimensions:

• Overall Length: 19 3/16 ± 3/8 inches
• Bulb Diagonal: 16 5/8 ± 1/8 inches
• Bulb Width: 15 3/8 ± 1/8 inches
• Bulb Height: 12 1/4 ± 1/8 inches
• Minimum Useful Screen Diagonal: 15 5/16 inches
• Minimum Useful Screen Width: 14 1/4 inches
• Minimum Useful Screen Height: 10 3/4 inches
• Raster Size: 14 1/4 inches by 10 3/4 inches

The deflection system operates magnetically, providing a horizontal deflection angle of 65 degrees and a diagonal deflection angle of 70 degrees.

Optically, the tube is equipped with a No. 4 phosphor screen, which is a sulfide type that produces white fluorescence and phosphorescence with medium persistence. The faceplate light transmission at the center is approximately 66%.

Electrical Ratings and Typical Operation

The electrical ratings for the 17LP4A are established under the design center system. The heater operates at a nominal voltage of 6.3 V with a current of 0.6 A.

Maximum Ratings (Design Center Values)

• Grid No. 3, Grid No. 5, and Collector Voltage: 16,000 V DC
• Grid No. 4 Voltage: -500 to +1000 V DC
• Grid No. 2 Voltage: 500 V DC
• Grid No. 1 Voltage:
  • DC negative-bias: 125 V
  • DC positive-bias: 0 V
  • Peak positive: 2 V
• Peak Heater-Cathode Voltage:
  • Heater negative to cathode during warm-up (less than or equal to 15 seconds): 410 V
  • Heater negative to cathode after warm-up: 180 V
  • Heater positive to cathode: 180 V
• Grid No. 1 Circuit Resistance: 1.5 megohms maximum

Typical Operating Conditions

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

• Grid No. 3, Grid No. 5, and Collector Voltage: 12,000 V DC
• Grid No. 2 Voltage: 300 V DC
• Grid No. 1 Voltage (for visual extinction of undeflected spot): -33 to -77 V DC
• Grid No. 4 Voltage (approximate): -48 to +260 V DC. This corresponds to a focus range of -0.4% to +2.2% of the collector voltage.
• Grid No. 4 Current: -15 to +25 uA
• Grid No. 2 Current: -15 to +15 uA
• Ion Trap Field Strength: Approximately 35 Gausses, achieved using a single-field magnet such as the RETMA #111 or an equivalent.

Wiring, Pin Connections, and Capacitances

The 17LP4A uses a small shell duodecal 6-pin base (designation B6-63) with a 12L basing arrangement. The high-voltage bulb contact is a recessed small cavity cap (J1-21), which aligns with pin position #6 within a tolerance of ±30 degrees.

Pinout Configuration (Bottom View)

The electrical connections to the base pins and anode cap are assigned as follows:

Interelectrode Capacitances

The approximate capacitances of the tube's electrodes are:

• Cathode to all other electrodes: 5 uuf
• Grid No. 1 to all other electrodes: 6 uuf
• External conductive coating to collector: 750 uuf minimum to 1,500 uuf maximum

Technical Summary

The 17LP4A is a 17-inch class rectangular glass television picture tube featuring an aluminized screen, low-voltage electrostatic focus, and magnetic deflection. Operating with a 6.3 V, 0.6 A heater, it is rated for a maximum collector voltage of 16,000 V, with a typical operating point of 12,000 V. Its physical design incorporates a duodecal 6-pin base and a recessed cavity cap for high-voltage connection, supported by an external single-field ion trap for beam alignment.