1403AB — Flying Spot Scanner Tube

The 1403AB is a 14-inch diagonal rectangular cathode-ray tube designed primarily for general flying spot scanner applications. Manufactured by Ferranti, it features a metal-backed screen, an external conductive coating, low-voltage electrostatic focusing, and magnetic deflection. The tube is characterized by its Type 'A' phosphor, which provides green fluorescence with ultra-short persistence.

Physical Construction and Base Connections

The 1403AB is constructed with a rectangular glass envelope and has a nominal neck diameter of 37 mm (specified as 36.5 ± 1.5 mm in mechanical drawings). The tube has a maximum overall length of 420 mm (with a design dimension of 410 ± 10 mm) and can be mounted in any position.

The faceplate features a 686 mm radius of curvature, and the bulb design provides a 65-degree deflection angle. The useful screen area is defined by a minimum width of 292 mm, a minimum height of 218 mm, and a minimum diagonal of 323 mm, with an overall diagonal dimension of 348 ± 3 mm.

An external conductive coating is applied to the envelope, which provides an approximate capacitance of 1100 pF to the anode and may be utilized for extra-high tension (E.H.T.) smoothing. The tube utilizes a B12A (Duodecal) base and a CT8 (Cavity Type) anode cap.

The B12A base connections, viewed from the underside, are allocated as follows:

Heater and Electrical Ratings

The 1403AB is equipped with an indirectly heated cathode. The nominal heater requirements and absolute electrical ratings are defined to ensure reliable operation:

Heater Characteristics

• Heater Voltage: 6.3 V
• Heater Current: 0.3 A
• Series Operation Limit: Under series connection, the surge heater voltage must not exceed 9.5 V r.m.s. A current-limiting device must be incorporated in the circuit to restrict the switching surge.

Absolute Maximum and Minimum Ratings

• Maximum First Anode ($A_1$) Voltage: 500 V
• Minimum First Anode ($A_1$) Voltage: 200 V
• Maximum Combined Second and Fourth Anode ($A_2 + A_4$) Voltage: 15 kV
• Minimum Combined Second and Fourth Anode ($A_2 + A_4$) Voltage: 8 kV
• Maximum Positive Third Anode ($A_3$) Voltage: +500 V
• Maximum Negative Third Anode ($A_3$) Voltage: -500 V
• Maximum Heater-to-Cathode Voltage ($V_{h-k}$): 200 V
• Maximum Grid-to-Cathode Resistance ($R_{g-k}$): 1.5 MΩ
• Maximum Heater-to-Cathode Resistance ($R_{h-k}$): 1.0 MΩ

Typical Operating Conditions and Capacitances

Under typical operating conditions, the electrostatic focusing and grid bias parameters are configured as follows:

• First Anode ($A_1$) Voltage: 300 V
• Second and Fourth Anode ($A_2 + A_4$) Voltage: 12 kV
• Third Anode ($A_3$) Voltage for Focus: -300 to +300 V (the point of optimum focus lies within this range)
• Grid Voltage ($V_g$) for Visual Cut-off: -40 to -80 V

The grid must never be allowed to become positive with respect to the cathode during normal operation. An exception is permitted immediately after switching off the device, during which the grid voltage may rise to a maximum of +1 V.

Interelectrode Capacitances

• Cathode to all other electrodes ($C_{k-all}$): < 8 pF
• Grid to all other electrodes ($C_{g-all}$): < 8 pF
• Anode to external conductive coating ($C_{a-ext. coating}$): Approximately 1100 pF

Related Phosphor Designations

The 1403AB belongs to a family of closely related flying spot scanner tubes sharing identical physical dimensions, electrical ratings, and base configurations, but differing in screen phosphor characteristics:

• 1403AB: Features Type 'A' phosphor with green fluorescence and ultra-short persistence.
• 14/03QB: Features Type 'Q' phosphor with blue/violet fluorescence and killed persistence.
• 14/03Q2B: Features Type 'Q2' phosphor with magenta fluorescence. For applications utilizing this variant, a blue filter should be provided for the associated photocell to separate the two color peaks, which exhibit different persistence times.

Technical Summary

The 1403AB is a specialized 14-inch rectangular flying spot scanner tube featuring magnetic deflection and low-voltage electrostatic focusing. Operating with a 6.3 V, 0.3 A heater, the tube is designed for high-voltage operation with a typical anode potential of 12 kV and a first anode potential of 300 V. Its B12A Duodecal base and CT8 cavity cap provide robust connections for its multi-anode configuration. With its Type 'A' green phosphor and ultra-short persistence, the 1403AB is optimized for high-speed optical scanning applications requiring rapid decay times.