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Discussion Starter · #1 ·
I'm debating going to a dual dish DirecTV configuration to better combat rain fade on 119. Right now with the single dish config, I get roughly 82-92 across all transponders on 101, and 55-70 on 119. I could go with two 24" dishes, or keep my oval dish for 101 and adding a 24 or 30 incher for 119.


I've found the specs on Winegard's site for their round dishes, but I can't find any information on 24" elliptical (my existing DirecTV Plus dish).


My question is: If I use the oval dish for 101 A, I assume I'd get the best gain using the LNB C postition (normally pointed at 110). I realize I'd have to set the tilt back to 0, and point the dish directly at 101. Am I just pissing in the wind? Is it worth trying to re-use the oval dish, or dumping it?
 

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If you use your elliptical dish for 101 W exclusively, you'll get at least the signal strength you show now, and probably a bit more. The LNB will, indeed, have to be mounted in the "SAT C" central location. Do NOT buy a ChannelMaster "Sat C" kit, though. That has a special LNB using a different intermediate frequency. Your elevation setting will have to be modified, too, since the "SAT C" LNB mount physically sits lower in the extension arm adaptor than either the "SAT A" or "SAT B" positions.
 

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The C position offers no advantage over the A & B positions. Each of the LNB positions uses a dish surface area that is equivalent to an 18" dish. The feedhorn of the LNB limits the area of the dish that is useable by the LNB. In the center C position the edges of the elliptical dish are not seen by the LNB.
 

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Discussion Starter · #4 ·
Ray,


Right - I wasn't planning on a LNB-C kit. This is a budget-constrained project!:D


Kevin - that's what I was afraid of. I was hoping that the fabrication method used for the elliptical dish (economics, you know!) would tend to make the C-position a little better tuned... I guess I could always do a little experimental verification. Plus any work put into "deforming" the dish to favor the C-position would outway the cost of just going ahead with two new round dishes. Maybe I can find a couple of 24" dishes at neighborhood garage sales...
 

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Keep in mind that the effective surface area has to be substantially increased to obtain a noticeable improvement in performance. In most cases anything less than double isn't worth the effort.


Some overly simplified math:


18" = 9^2 * 3 = 243 (reference)

24" = 12^2 *3 = 432 (1.8x)

30" = 15^2 * 3 = 675 (2.8x)


You may be able to find some old Primestar dishes at garage sales :p
 
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