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T7840: Difference between revisions
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{{CRT | |||
|Manufacturer=Tektronix | |||
|Model=T7840 | |||
|Part_nos=154-0713-00, 154-0713-04 | |||
|Description=[[dual-beam CRT]] | |||
|Used_in=7844 | |||
|Designers=Conrad Odenthal; Ken Hawken | |||
}} used in the [[7844]] scope, introduced in 1974. It was designed by [[Conrad Odenthal]] and [[Ken Hawken]]. | |||
It has distributed vertical deflection plate pairs and | 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. | |||
==Links== | |||
* Murlan Kaufman, [[Media:Tekscope_1974_V6_N4.pdf | ''A 400 MHz dual-beam oscilloscope.'']] Tekscope Vol.6 No.4, Sept/Oct 1974, p.3 | |||
* [[Patent US 3819984A|US Patent 3819984A – Side-by-side dual gun crt having horizontal deflector plates provided with side shields for correction of geometric distortion]] ([[Ken Hawken]]) | |||
* [[Patent US 3983444A|US Patent 3983444A – Dual beam CRT with inner gun and outer gun shield means for correcting keystone distortion]] ([[Conrad Odenthal]]) | |||
* [[Patent US 3921025A|US Patent 3921025A – Dual-beam CRT with vertical trace bowing correction means]] ([[Conrad Odenthal]]) | |||
[[Category:Dual-beam CRTs]] | [[Category:Dual-beam CRTs]] | ||