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Any recommedation on acheiving a good vertical tilt on a directional antenna?[/quote]
Tilting a screen-type antenna is a lot harer than tilting a yagi, but it can be done. My suggestion to you would be to check with MidwestDX'r, as I know he has done it. Also, you can look the "Erecting an antenna" website, which also has some good info.
http://www.hdtvprimer.com/issues/erecting_antenna.html