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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Jan 15, 2008 2:58 pm Post subject: |
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Might be an idea to add this link into the FAQ...
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rod
Joined: 18 Mar 2006
Posts: 418
Location: Northern Ontario, Canada
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what rating would you give the tube displaying the mica/phosphur assembly? I see a little uneven wear in the grid there. maybe a 5 or 6?
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Rod
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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jask
Joined: 17 Mar 2006
Posts: 10187
Location: kamloops BC
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Nasty!!
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1031
Joined: 22 Mar 2006
Posts: 657
Location: Finland
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kschmit2
Joined: 09 Mar 2006
Posts: 1141
Location: Heidelberg, Germany
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| Posted: Wed Jan 16, 2008 10:09 am Post subject: |
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this 1960 portable CRT PJ is currently for sale on Ebay Germany (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190190257320)
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Kai
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| Datasheet Philips VE 2609 |
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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I know someone explained this to me a few years back, but can someone tell me again why the CRT tubes were round? Was it an early manufacturing limitation that prevents immediate adoption to squaring the overall shape with rounded corners? I'm guessing the need to stay away from perfect square edges has to do with cooling of the glass (i.e. eliminating facial hot spots).
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lyd
Joined: 15 Sep 2007
Posts: 390
Location: Lake Mills, Wi
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| Posted: Wed Jan 16, 2008 12:14 pm Post subject: Re: History of CRTs |
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Interesting, but the guy ought to be strung up by his thumbs for that page design. All those absolutely positioned elements are bad news.
lyd
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r.bauer
Joined: 08 Apr 2006
Posts: 280
Location: The Netherlands
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| Posted: Wed Jan 16, 2008 12:21 pm Post subject: |
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Because of reduced stress in round objects.
In the make your own tube link : http://www.earlytelevision.org/14ap4_construction.html it shows clearly how tubes were made in the early days.
If you make it more rectangular shaped, the stresses in the material will increase and the glass needs to be thicker, hence making it more complicated, and more expensive to make. Other reason might be focussing the electron beam. In the old days, dynamically adjusting focus (even for ES-focus tubes) for different distance from electron gun to fosfor in the center compared to the edge of the tube was not so common. This problem was not number one on their ToDo list.
Even in normal TV-sets it took a long time before the tubes became really square. The increase in weight in these sets was enormous!
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Thu Jan 17, 2008 10:32 am Post subject: |
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Ok, so why was this carried through into the 1990's?
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Dave Lister
Joined: 16 Jan 2007
Posts: 436
Location: Adelaide, South Australia
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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, that was until someone came up with the marketing idea of flat screens being the new thing to have and everyone just had to 'keep up with the Joneses'. 