RX sig strength 7 db lower with POTY

  • Hallo Jabi,

    take 3 very small pieces of a mirror and glew it in the dish at different places. The mirror surfaces must be parallel to the dish. With thin double-sided adhesive tape it will work. Turn the dish to the sun. With a sheet of paper you will see, where the sun beams meet. With this method it can be seen also , if the dish surface and the paraboloid shape are correct still.

    Have fun.
    73
    Andreas

  • Hallo,

    here is a picture of a dish with beams (read lines) from the mirrors to the focus point. The mirror pieces are cracked from a bigger mirror. Take care not to get injured.

    The reason for this method was a false mounting. The wholes in the dish allowed to mount it wrong, the upper side was at the right side. It didn't work at all, no focus, much frustration. With the mirrors I found my misteake easily. With the top side on top, all is fine.
    It is a little bit difficult to hit the sun but with some trials it will be ok. Follow the beams from the mirrors to the focus, the correct position can be found. It can be used also with a dish and unknown focus point.

    73
    Andreas

  • I see, its a way to find the focus on the LNB or feeder. What I meant is the way to find the focus on the Dish with a laser pointer. On a prime focus Dish its easy, the focus is in the middle of the Dish. This way is also possible with a TV offset Dish. I mounted my helix feeder on top of the LNB and "pointered" it nearly to the focus of the LNB. The point is also in the horizontal center and a little bit over the LNB's point. You need a good eye measure and it works.