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![]() Apologies in advance if this is considered OT. I am having a minor problem with the display on my spectrum analyser Mk2 project, see http://www.hanssummers.com/electroni...ser2/index.htm .. The display for this analyser is an 4.5-inch ex-TV tube. I successfully dismantled that TV and rebuilt the necessary drivers etc as a miniature monitor having TTL-level video and composite sync inputs. Naturally the type of display this tube is now being subjected to is very different to a TV picture. There seem to be some problems with the video drive circuits, see pictures at the bottom of the above web page. The graticule fades out in the top eighth of the screen. Also see the "noise floor" photo which shows significant horizontal "bulge". Also there is a resolution problem - one spectrum analyser sweep consists of 640 measurements, and I have a complicated interpolation circuit which "joins the dots" i.e. draws lines between the individual measurements, and also reduces the horizontal resolution to 320 pixels which I hoped would be displayable on the monitor. Problem is I can only get 160 horizontal pixels to display reliably - at 320 pixels a vertical line is very faint or invisible (depending on how much white there was in the preceeding microsecond or so's worth of scan line. The circuit diagram is also on that page (http://www.hanssummers.com/electroni...yser2/circuitm ..pdf). I'm no TV expert. Can anyone suggest what modifications should be made to the video driver circuit to correct these problems? Alternatively what newsgroup might be populated with TV gurus? 73 Hans G0UPL |
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