As for the attic install <--> As a learning experience.
You can start with the ANT751 antenna in the attic.
If reception situation problems happen that are not resolvable with antenna aim and location adjustments in the attic.
Then move/install the ANT751 above the roof as directed.
Remove and discard , rubber weather boots , rubber weather boots take in and hold water inside the boot , this is not good for connections.
To keep Weather/Water out of outside coax and connectors , use the coax that has the Compression type connectors on the ends of the coax , not the old crimp type connectors.
To make double sure that weather/water does not get into outside connections use ,
http://www.coaxseal.com.
Can also completely wrap the matching transformer (balun) that connects the antenna to the coax with coaxseal.
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For 3 Tv's connected , use a simple common 3 way splitter.
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You can Test reception , with and without a , Winegard LNA-100 'Boost' antenna system amplifier.
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Here are some places to buy antennas and etc. .
http://www.winegarddirect.com.
http://www.solidsignal.com.
http://www.amazon.com.
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Sometimes HomeDepot and Lowes will have the ANT751 antenna in the store , no mater what the Home Depot and Lowes web sites say.