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<blockquote data-quote="Old Fred" data-source="post: 25118">Actually, I doubt if the polariser will have any significant effect. It may reduce the signal to the LNB by around 0.3dB but that's all.Most likely what's happening is this: An LNB has a characteristic called &quot;cross-polar isolation&quot;. I believe this is related to its ability to ignore or reject signals of the opposite polarisation to the one selected.If the vertically polarised signals are very strong indeed, the LNB will be unable to reject them. It will in effect be &quot;blinded&quot; and unable to see the weaker horizontally polarised signals.I guess an easy way to test this theory is to tape some pieces of cardboard or plastic over the feedhorn to reduce the signal from the dish to the level that the 1.2m dish was giving.However, you should first optimise the LNB skew position by monitoring the signal quality in the &quot;Manual Tuning&quot; menu with the weaker transponder parameters typed into that menu.This is guesswork based on what I've read (I'm not an installer) but logic tells me I'm not far off the mark.Fred</blockquote>

[QUOTE="Old Fred, post: 25118"] Actually, I doubt if the polariser will have any significant effect. It may reduce the signal to the LNB by around 0.3dB but that's all. Most likely what's happening is this: An LNB has a characteristic called "cross-polar isolation". I believe this is related to its ability to ignore or reject signals of the opposite polarisation to the one selected. If the vertically polarised signals are very strong indeed, the LNB will be unable to reject them. It will in effect be "blinded" and unable to see the weaker horizontally polarised signals. I guess an easy way to test this theory is to tape some pieces of cardboard or plastic over the feedhorn to reduce the signal from the dish to the level that the 1.2m dish was giving. However, you should first optimise the LNB skew position by monitoring the signal quality in the "Manual Tuning" menu with the weaker transponder parameters typed into that menu. This is guesswork based on what I've read (I'm not an installer) but logic tells me I'm not far off the mark. Fred [/QUOTE]

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