17HP4B — Electrostatic-Focus Magnetic-Deflection Cathode Ray Tube

The 17HP4B is a direct-view, all-glass cathode ray tube (picture tube) designed primarily for use in television receivers. It features electrostatic focusing, magnetic deflection, a unipotential cathode, and a rectangular glass construction. The tube is equipped with an external conductive coating and requires an external single-field ion-trap magnet.

Overview and Comparison

The 17HP4B is characterized by its rectangular screen and reflective aluminized backing. It is electrically and mechanically identical to the 17HP4 and 17HP4A models, with the primary distinction being the screen construction:

• The 17HP4 utilizes a standard grey filter faceplate.
• The 17HP4A features a grey frosted filter faceplate.
• The 17HP4B incorporates a highly reflective aluminized screen.

The screen uses a No. 4 (P4) sulfide-type phosphor, which produces a white fluorescence and phosphorescence with medium to short persistence. The faceplate is spherical and made of gray glass, providing an approximate center light transmission of 66% to 72%.

Mechanical Specifications

The physical envelope of the 17HP4B is a rectangular glass bulb with a nominal deflection angle of 70° diagonally, 65° horizontally, and 50° vertically. The tube can be mounted in any position.

Physical Dimensions

• Overall Length: 19 3/16 ± 3/8 inches (varying up to 19 3/8 ± 3/8 inches in some specifications)
• Neck Length: 7 1/2 inches
• Greatest Bulb Dimensions:
  • Diagonal: 16 5/8 ± 1/8 inches (or 16 5/8 ± 3/32 inches)
  • Width: 15 3/8 ± 1/8 inches (or 15 25/64 ± 1/8 inches)
  • Height: 12 1/4 ± 1/8 inches
• Minimum Useful Screen Dimensions:
  • Diagonal: 15 1/2 inches
  • Width: 14 1/4 inches (or 14 5/16 inches)
  • Height: 10 3/4 inches
• Raster Size: 10 3/4 inches by 14 1/4 inches
• Net Weight: Approximately 16 lbs

Connections and Alignment

The tube uses a small-shell duodecal 6-pin base (JETEC No. B6-63) with a 12L basing designation. The high-voltage anode connection is made via a recessed small-cavity cap (JETEC No. J1-21). The anode contact is aligned with pin position No. 6 within a tolerance of ±30 degrees.

Electrical Characteristics and Basing

The 17HP4B is equipped with an indirectly heated, unipotential cathode. The heater is designed for a nominal 6.3 V supply.

Heater Ratings

• Heater Voltage: 6.3 V
• Heater Current: 0.6 A (with a tolerance of ±10%)

Direct 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: 1500 µµF maximum, 750 µµF minimum

Pinout Configuration (12L Bottom View)

• Pin 1: Heater
• Pin 2: Grid No. 1
• Pin 6: Grid No. 4 (Focusing Electrode)
• Pin 10: Grid No. 2
• Pin 11: Cathode
• Pin 12: Heater
• Anode Cap: Grid No. 3, Grid No. 5, Collector (connected internally)

Maximum Ratings (Design-Center Values)

The following absolute limits must be observed to ensure reliable operation and prevent damage to the tube:

• Anode Voltage (Grid No. 3, Grid No. 5, Collector): 16,000 V DC maximum
• Focusing-Electrode (Grid No. 4) Voltage: -500 to +1000 V DC maximum (or 500 V DC maximum depending on the specific rating system)
• Grid No. 2 Voltage: 500 V DC maximum
• Grid No. 1 Voltage:
  • DC Negative-Bias Value: 125 V DC maximum
  • DC Positive-Bias Value: 0 V DC maximum
  • Positive-Peak Value: 2 V maximum
• Peak Heater-Cathode Voltage:
  • Heater negative with respect to cathode during warm-up (≤ 15 seconds): 410 V maximum
  • Heater negative with respect to cathode after warm-up: 180 V maximum
  • Heater positive with respect to cathode: 180 V maximum
• Grid No. 1 Circuit Resistance: 1.5 Megohms maximum

Typical Operating Conditions

Under typical operating conditions, the focusing electrode (Grid No. 4) operates at a low voltage relative to the anode, allowing for electrostatic focusing without requiring high-voltage auxiliary supplies.

• Anode Voltage: 14,000 V DC (with a minimum recommended operating voltage of 12,000 V DC)
• Grid No. 4 (Focusing Electrode) Voltage: -56 to +310 V DC (or -56 to +308 V DC; the focusing electrode may be modulated within this range to maintain focus across the raster)
• 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 or undeflected spot): -33 to -77 V DC (or -28 to -72 V DC)
• Ion-Trap Magnet Field Requirements:
  • Standard Coil No. 111: Approximately 85 mA current
  • JETEC Ion-Trap Magnet No. 117: Approximately 37 Gausses (equivalent to 37 mA)

Circuit Design Recommendations

The cathode should be returned directly to one side or to the center tap of the heater transformer winding to minimize potential differences and hum injection.