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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
feedhorn confusion
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<blockquote data-quote="pete_l" data-source="post: 394916" data-attributes="member: 226657"><p>I'm using a C120 LNB with an Invacom ADF-120 adjustable feedhorn. </p><p></p><p>The <a href="http://www.invacom.com/documents/AdjustableFeedHorn.pdf" target="_blank">datasheet</a>. for the feedhorn states it has an adjustable beam width </p><p>F/D of 0.32 to 0.43. Now, the calculator <a href="http://www.satellite-calculations.com/Satellite/reflector.htm" target="_blank">here </a>tells me that my 2.4m dish</p><p>has a F/D of 0.38, OK so far. There are 2 graphs on the datasheet.</p><p>From the first one, I can see that for a F/D of 0.38, I need to screw the</p><p>feedhorn in for a 4mm protrusion. (I guess this means the thread is </p><p>protruding 4mm proud of the corrugations).</p><p></p><p>The problem I have is with the second graph. The "Y" axis has no units.</p><p>The 4mm protrusion from graph 1 seems to correspond to "120" on the</p><p>second graph - but I don't know what it's 120 of. Can anyone shed any</p><p>light on what this graph signifies?</p><p></p><p>Thanks,</p><p>Pete</p></blockquote><p></p>
[QUOTE="pete_l, post: 394916, member: 226657"] I'm using a C120 LNB with an Invacom ADF-120 adjustable feedhorn. The [URL="http://www.invacom.com/documents/AdjustableFeedHorn.pdf"]datasheet[/URL]. for the feedhorn states it has an adjustable beam width F/D of 0.32 to 0.43. Now, the calculator [URL="http://www.satellite-calculations.com/Satellite/reflector.htm"]here [/URL]tells me that my 2.4m dish has a F/D of 0.38, OK so far. There are 2 graphs on the datasheet. From the first one, I can see that for a F/D of 0.38, I need to screw the feedhorn in for a 4mm protrusion. (I guess this means the thread is protruding 4mm proud of the corrugations). The problem I have is with the second graph. The "Y" axis has no units. The 4mm protrusion from graph 1 seems to correspond to "120" on the second graph - but I don't know what it's 120 of. Can anyone shed any light on what this graph signifies? Thanks, Pete [/QUOTE]
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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
feedhorn confusion
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