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Feb 14th, 2008 at 1:48pm
The LNB may have a clamp round the feed throat which, if loosened, will allow the LNB to be rotated. When setting up satellite TV LNBs, start with the LNB upright. The hairline mark will be at the top. Then rotate either way by the required angle. Any scale may be very small or non-existent, in which case you can wrap a strip of paper round, measure the circumference. Calculate the length for 5.5 deg = circum x 5.5 /360. Mark the strip, reposition and turn the required amount. It is not too critical on a receive-only system, only you suffer if it is wrong.
The calculated polarisation angle for you is -12.5 deg, add 7 for Astra and the result is -5.5 deg. This means that while facing towards the satellite you turn the LNB 5.5 deg anticlockwise. Not far at all. If you adjust using the signal quality readout on the receiver turn the feed till you get a severely degraded but exactly recorded degradation, then turn to the opposite side for exactly the same degradation and half the angles.
All above assumes you have a simple dish intended to be pointed permanently at one satellite using an azimuth/elevation mount. Quite different considerations apply if it is motor driven and your indoor box is intended to steer the dish to point at all visible satellites. If your dish has a motor please say and we will start again.
Regards, Eric.
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