Sky Mk4 Quad LNB - Orientation

Discussion in 'Sky Digital TV Forum' started by Free To Air, Aug 21, 2013.

  1. Free To Air

    Free To Air
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    Hi,

    Looking at a Sky Zinwell Mk4 LNB, the feedhorn and cap are elliptical shaped rather than round.

    If the LNB is in the feedarm clamping bracket with the polarity indicator marks aligned with the arrow on the clamping bracket, then the LNB feedhorn & cap ellipse is at 90 degrees to the dish face ellipse.

    To put it another way, the Sky Zone 2 Mk4 dish face elliptical shape has the longest axis of the ellipse running horizontally, ie it is wider that it is tall. When the LNB is is the bracket lined up with the polarity marks the LNB feedhorn and cap ellipse is taller than it is wide.

    Is this OK, it looks like it would miss a lot of signal coming from the dish due to the two elliptical shapes being at 90 degrees to each other?



    Rgds
    FTA
     
  2. excollier

    excollier
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    That sounds right. Another way to check is if you look towards the face of the dish from behind the lnb, do the cable f-connectors point to roughly 7o'clock? That is the correct skew.
     
    Last edited: Aug 21, 2013
  3. winston2010

    winston2010
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    The wider part of the dish receives a narrower beam (sharper focus) hence a narrower part of the feedhorn.

    This is why special LNBs are required for Sky dishes. The Satcure website explains it well.
     
  4. MartinPickering

    MartinPickering
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    Correct. The wider the horn, the narrower its "field of view".
    LNB mysteries explained - part 1
     

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