17DRP4 — Television Picture Tube
The 17DRP4 is a 17-inch rectangular, direct-view television picture tube. It features an extremely short design with low-voltage electrostatic focusing and 110-degree magnetic deflection. The tube is designed with internal magnetic shielding in the gun structure, which permits the use of deflecting yokes without requiring special external magnetic shields. This internal shield is visually identified by a distinctive yellow base.
Other key features of the 17DRP4 include an unusually low heater power requirement, an aluminized metal-backed screen with a P4-Sulfide Type phosphor, and a straight electron gun design that requires no ion-trap magnet. The tube uses a short integral glass-button base with straight-through leads and an indexing lug.
Mechanical and Physical Characteristics
The 17DRP4 is a compact and lightweight cathode-ray tube, weighing approximately 10 lbs. Its physical dimensions and mechanical specifications are highly optimized for space-saving television receiver designs.
Envelope and Screen Dimensions
The tube utilizes a J132 1/2 A1 bulb with a spherical filterglass faceplate that provides approximately 77% light transmission at the center. The screen uses a P4 phosphor, which produces a white fluorescent color with medium persistence.
- Projected Area of Screen: 155 sq. in.
- Minimum Useful Screen Dimensions:
- Diagonal: 15 3/4 inches
- Width: 14 3/4 inches
- Height: 11 11/16 inches
- Greatest Bulb Dimensions:
- Diagonal: 16 9/16 ± 1/8 inches
- Width: 15 5/8 ± 1/8 inches
- Height: 12 3/4 ± 1/8 inches
- Overall Length: 10 13/16 inches (with tolerances of ±3/16 inch or ±3/8 inch depending on standard)
- Neck Length: 3 11/16 inches (with tolerances of ±1/16 inch or ±1/8 inch)
Deflection and Mounting
The tube has an approximate diagonal deflection angle of 110°, with a horizontal deflection of 105° and a vertical deflection of 87°. The reference line is determined by a JETEC No. 126 gauge.
An external conductive coating of the Modified-Band type is applied to the bulb, providing a grounding contact near the reference line. The area around the anode button has an insulating coating. The bottom circumference of the base wafer falls within a 1 3/4-inch diameter circle concentric with the bulb axis.
To prevent mechanical stress, the socket must not be rigidly mounted; it must have flexible leads that allow free movement and avoid impressing lateral strains on the pins.
Heater and Electrical Connections
The 17DRP4 is designed with a highly efficient heater optimized for series-string television receiver applications.
Heater Ratings
The heater has a controlled warm-up time of 11 seconds. This warm-up time is defined as the time required to reach 80% of the rated heater voltage when four times the rated voltage is applied in series with a resistance equal to three times the rated heater resistance.
Base and Pinout Configurations
The tube features a JEDEC No. B7-208 Small-Button Neoeightar 7-Pin base (Arrangement 1) with an 8JK bottom-view basing designation. The high-voltage anode connection is made via a recessed small cavity cap (JEDEC No. J1-21), which aligns with the center line between pin 6 and pin 7 within ±30°.
Because different technical records list variations in the pin assignments for the 8JK basing, both documented configurations are presented below:
Pinout Configuration A
- Pin 1: Heater
- Pin 2: Grid No. 2
- Pin 3: Grid No. 1
- Pin 4: Grid No. 4 (Focus)
- Pin 6: Grid No. 2
- Pin 7: Cathode
- Pin 8: Heater
- Cap: Anode (Grid No. 3, Grid No. 5, Screen, Collector connected internally)
- External Coating: Grounding contact
Pinout Configuration B
- Pin 1: Heater
- Pin 2: Grid No. 1
- Pin 3: Grid No. 2
- Pin 4: Grid No. 4 (Focus)
- Pin 6: Cathode
- Pin 7: Heater
- Cap: Anode (Grid No. 3, Grid No. 5, and Anode connected internally)
- External Coating: Grounding contact
Interelectrode Capacitances
- Cathode to all other electrodes: 3.65 pF
- Grid No. 1 to all other electrodes: 4.15 pF
- External conductive coating to anode: 900 pF minimum / 1400 pF maximum
Operating Modes and Electrical Ratings
The 17DRP4 can be operated in either Grid-Drive Service or Cathode-Drive Service. The maximum ratings are defined under both the Design-Maximum and Absolute Maximum systems.
Maximum Ratings
The following table outlines the maximum limits for both operating services. Voltages are positive with respect to the cathode in Grid-Drive Service, and positive with respect to Grid No. 1 in Cathode-Drive Service, unless otherwise specified.
Peak Heater-Cathode Voltage Limits
These limits apply to both Grid-Drive and Cathode-Drive services:
- Heater negative with respect to cathode:
- During equipment warm-up period (≤ 15 seconds): 450 max V
- After equipment warm-up period: 200 max V
- Heater positive with respect to cathode:
- Combined AC and DC voltage: 200 max V
- DC component: 100 max V
Typical Operating Conditions
Under typical operating conditions, the tube is operated at an anode potential of 14,000 V DC.
Grid-Drive Service
Voltages are positive with respect to the cathode.
- Anode Voltage: 14,000 V DC
- Grid No. 4 Voltage (Focus): 100 to 500 V DC
- Grid No. 2 Voltage: 300 V DC
- Grid No. 1 Voltage for visual extinction of focused raster: -35 to -72 V DC
(Note: For cutoff of an undeflected focus spot, the absolute bias value increases by approximately 5 V.)
Cathode-Drive Service
Voltages are positive with respect to Grid No. 1.
- Anode Voltage: 14,000 V DC
- Grid No. 4 Voltage (Focus): 150 to 550 V DC
- Grid No. 2 Voltage: 300 V DC
- Grid No. 1 Voltage: 0 V DC
- Cathode Voltage for visual extinction of focused raster: +34 to +60 V DC
(Note: For cutoff of an undeflected focus spot, the absolute bias value increases by approximately 5 V.)
Safety Considerations
When operating the 17DRP4, safety precautions regarding X-ray radiation must be observed. If the tube is operated at anode voltages higher than 16,000 Volts, appropriate X-ray radiation shielding may be necessary to protect users and service technicians.
Technical Summary
The 17DRP4 is a highly specialized, short-neck 17-inch rectangular television picture tube designed for space-efficient and low-power receiver designs. By combining a 110-degree magnetic deflection angle with low-voltage electrostatic focusing, it achieves a remarkably short overall length of under 11 inches. Its design eliminates the need for an ion-trap magnet and external magnetic shielding, utilizing an internal shield instead. Operating at a typical anode voltage of 14,000 V, the tube supports both grid-drive and cathode-drive configurations, with a controlled 11-second heater warm-up cycle that makes it ideal for series-string entertainment equipment.
