feedhorn confusion | |
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01-06-2007
| #1 | ||
| Member Join Date: 30-05-2006 Location: S.E. England
Posts: 5
Thanks: 1
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My System: nothing yet - gathering info |
I'm using a C120 LNB with an Invacom ADF-120 adjustable feedhorn. The datasheet. for the feedhorn states it has an adjustable beam width F/D of 0.32 to 0.43. Now, the calculator here 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 | ||
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02-06-2007
| #2 | ||
| Regular Member Join Date: 08-02-2005 Location: Lot, Dordogne, Correze border.
Posts: 163
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My System: Dbox + Skystar2, 2.2m Kinhuge Dish with Inverto LNB and Invacom ADF-120 feedhorn. Pace 1.3.25 and 80cm for Sky. | Looks like beam width (in degrees). Last edited by Low Profile; 02-06-2007 at 01:35 PM | ||
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| The Following User Says Thank You to Low Profile For This Useful Post: | pete_l (02-06-2007) |
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02-06-2007
| #3 | ||
| Member Join Date: 30-05-2006 Location: S.E. England
Posts: 5
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My System: nothing yet - gathering info | Ah ha! yes, that sounds right - thanks It does mean that my dish os too big, as the feedhorn beamwidth is calculated to be 133 degrees - so the feedhorn is only "seeing" 2.1 metres of the dish. :-( | ||
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24-09-2008
| #4 | |||
| Member Join Date: 19-08-2008 Location: Spain
Posts: 7
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My System: TM 5200 USB |
How do you adjust the feedhorn to get the required protrusion? Which bit do you screw in/out? I've looked but cannot figure it out! Dumb ass. | |||
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