Dish Problems

So we decided to upgrade to the HD version of DirecTV, which involves (of course!) replacing, or at least supplementing our current satellite dish. It has a triple horn on it, and looks at three birds simultaneously, instead of just the one, as the standard dish does. This means that not only are azimuth and elevation important, but there’s a third axis adjustment, that they call “tilt,” to make sure that you’re seeing all three of them.

I put up a new mast, got it plumb, set the settings on the tilt and elevation to what they’re supposed to be for southeast Florida (45 degrees for both), hooked up the cable, pointed it in the general azimuthal direction (about thirty degrees south of west), and got nada, bupkis, no signal.

Is the cable good? Yup, and here’s the weird thing. When I drop the elevation to thirty degrees or so (fifteen below where it’s supposed to be), I get a reasonably strong signal on the upper transponders of Satellite A, starting with number 22. No signal on transponders 1 and up (which are the ones you’re supposed to use to align the dish). Also no signal on either of the other two birds.

So something’s happening, but not what should be happening. What are the chances that this is an LNB problem? The first dish I ever installed, years ago, had a bad LNB right out of the box (which drove me crazy trying to figure out what was wrong–fortunately, part of the deal was a free upgrade to a dual LNB, and when I put in the new unit, I got the signal right away).

Is there anyone out there familiar with the situation who could diagnose this, so I can just take the LNB back to Circuit City and exchange it? Or are these symptoms of something else that I’m doing wrong (though I’m wracking my brains at this point trying to figure out what else it could be).