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<blockquote data-quote="archive10" data-source="post: 906796"><p>What I'm saying is:</p><p></p><p>The feedhorn that you have posted a picture of looks very much like a 39 degree feedhorn, which works with 0.8 f/D dishes. The 50 degree feedhorn which I assume is for 0.6 f/D dishes (and which is the only other Prodelin available for these dishes) looks quite different.</p><p></p><p>Furthermore, the feedhorn is lying on top a Prodelin model 1194 antenna manual. The 1194 uses 0.8 f/D reflector.</p><p></p><p>However, you prodelin antennas are model 1183 or 1184 and use reflector type 0179-189 (as in your pics), and they are 0.6 f/D reflectors.</p><p></p><p>Soooo... if you use the 0.8 f/D feedhorn with the 0.6 f/D dishes, you will in principle not "illuminate" the entire dish, but rather a smaller portion of it (as the feed is closer to the dish than with a 0.8 f/D feed mount should be). You will get, say, effectively a 160 cm dish...</p><p></p><p>Now, the Prodelin dish you got recently was a type 3180 ka-band dish (which are VERY epensive from new, by the way - list price 7500 USD and up + shipping - I suppose there is pixie dust in the plastic??). General Dynamics list this as an 0.8 f/D dish. In which case putting a standard LNB will "over-illuminate" the dish, i.e. go beyond the rim.</p><p></p><p>In other words: Use standard LNBs or CM/Gibby feedhorns with the 118x, and the Prodelin feedhorn with the 3180 to get best results...</p><p>(and keep the 3180 whatever you do, it should be quite rare if you ever venture into Ka-band reception...)</p></blockquote><p></p>
[QUOTE="archive10, post: 906796"] What I'm saying is: The feedhorn that you have posted a picture of looks very much like a 39 degree feedhorn, which works with 0.8 f/D dishes. The 50 degree feedhorn which I assume is for 0.6 f/D dishes (and which is the only other Prodelin available for these dishes) looks quite different. Furthermore, the feedhorn is lying on top a Prodelin model 1194 antenna manual. The 1194 uses 0.8 f/D reflector. However, you prodelin antennas are model 1183 or 1184 and use reflector type 0179-189 (as in your pics), and they are 0.6 f/D reflectors. Soooo... if you use the 0.8 f/D feedhorn with the 0.6 f/D dishes, you will in principle not "illuminate" the entire dish, but rather a smaller portion of it (as the feed is closer to the dish than with a 0.8 f/D feed mount should be). You will get, say, effectively a 160 cm dish... Now, the Prodelin dish you got recently was a type 3180 ka-band dish (which are VERY epensive from new, by the way - list price 7500 USD and up + shipping - I suppose there is pixie dust in the plastic??). General Dynamics list this as an 0.8 f/D dish. In which case putting a standard LNB will "over-illuminate" the dish, i.e. go beyond the rim. In other words: Use standard LNBs or CM/Gibby feedhorns with the 118x, and the Prodelin feedhorn with the 3180 to get best results... (and keep the 3180 whatever you do, it should be quite rare if you ever venture into Ka-band reception...) [/QUOTE]
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