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T7840: Difference between revisions
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info about electron gun structure from Kaufman article in Tekscope V6 N4 (1974)
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(info about electron gun structure from Kaufman article in Tekscope V6 N4 (1974)) |
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It has distributed vertical deflection plate pairs and separate horizontal deflection plate pairs. | It has distributed vertical deflection plate pairs and separate horizontal deflection plate pairs. | ||
Both beams can write to the full 8 cm × 10 cm screen area. | |||
Writing speed of a tube with [[phosphor|blue P11 phosphor]] was specified as 1.7 cm/ns on high-speed film (Polaroid type 47, 3000 ISO). | |||
The T7840 contains a dome-shaped metal mesh between the deflection plates and the screen, acting as a scan-expansion lens | |||
that increases the CRT's deflection sensitivity at the cost of some increase in spot size and intercepting some beam current. | |||
The latter loss is compensated by increasing the acceleration voltage to 24 kV. | |||
In the T7840, the two electron gun structures are placed side by side to eliminate the vertical overlap problem | |||
present in earlier dual-gun designs such as the [[T5560]] that place the guns on top of each other. | |||
The resulting horizontal overlap problem is solved by a pair of small auxiliary horizontal deflection plates | |||
between the vertical and horizontal deflection plate pairs of each gun. A DC voltage is applied to the extra plates | |||
to center the beams. | |||
[[Category:Dual-beam CRTs]] | [[Category:Dual-beam CRTs]] | ||