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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
Cassegrain Vs Gregorian
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<blockquote data-quote="koansrc" data-source="post: 473321" data-attributes="member: 244790"><p>Me neither. All photos of dual reflector prime focus dishes are Cassegrains. That's why I'm curious about the difference between offsets and gregorians.</p><p></p><p>I'm wondering whether the 2nd reflector on a prime focus dish (cas or greg) wiould actually increase reception ( by focusing stray rays that never make it to the feed ) or reduce reception due to the shadow it will obviously cast.</p><p></p><p>The very informative link/ .PDF Robbo71 posted and the excel file I think attempt to answer this question. But it's a bit over my head and needs some more understanding. </p><p></p><p>It seems that for my 3.0m prime I would need a subreflector with min diameter 44cm, an f/d 0,33 and 16,8cm focal.</p><p></p><p></p><p>:-snowman :-sman2 :-sugar :-Cbigsmil :-pachrist :-carrot :-fcm</p></blockquote><p></p>
[QUOTE="koansrc, post: 473321, member: 244790"] Me neither. All photos of dual reflector prime focus dishes are Cassegrains. That's why I'm curious about the difference between offsets and gregorians. I'm wondering whether the 2nd reflector on a prime focus dish (cas or greg) wiould actually increase reception ( by focusing stray rays that never make it to the feed ) or reduce reception due to the shadow it will obviously cast. The very informative link/ .PDF Robbo71 posted and the excel file I think attempt to answer this question. But it's a bit over my head and needs some more understanding. It seems that for my 3.0m prime I would need a subreflector with min diameter 44cm, an f/d 0,33 and 16,8cm focal. :-snowman :-sman2 :-sugar :-Cbigsmil :-pachrist :-carrot :-fcm [/QUOTE]
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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
Cassegrain Vs Gregorian
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