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ODD-LINE INTERLACE, MODIFIED SYNC PtILSES
Figure 5-30.-Structure of a vidicon tube

Aviation Electronics Technician 1 (Organizational)
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Figure 5-27.-Image orthicon tube. each striking electron liberates several more electrons, leaving a pattern of propottionate positive charges on the front of the target. When the back of the target is scanned by the beam from the electron gun in the base of the tube, enough electrons are deposited at each point to neutralize the positive charge. The rest of the beam returns to a series of electron multiplier stages or dynodes surrounding the gun. Each dynode is a metallic disk with openings similar to a pinwheel, and operates at a positive potential of 200 to 300 volts greater than the preceding dynode. Multiplication occurs through secondary emission at each dynode. If five dynode stages are used, each having a gain of 4, a gain of 1,000 (4 x 4 x 4 x 4 x 4) is realized in the multi- plier section. Now, consider dynodes with a gain of 5. The overall gain would be 5,000. This setup would allow the pickup tube to operate with relatively less light than the plumbicon or vidicon (to be discussed later). The electrons from the last dynode are routed through a signal-developing resistor to an extremely high B+ voltage. The output signal is then coupled to the first stage of video amplification in the camera. IMAGE ISOCON.— The image isocon tube (fig. 5-28) is similar to the image orthicon in construction and operation. The main difference is Figure 5-28.-Image isocon tube. 5-23







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