Higher antenna height and less to no signal blockage is the Key to your reception situation/location.
25 Feet is stronger Tv reception signal strengths.
Going higher then 25 feet will make reception more stronger.
Here are some antenna mounts for a higher antenna height with no guy wires.
http://www.ronard.com/Tripods%200703/4712.html.
http://www.palcoelectronics.com/pe300.aspx.
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Aim the YA1713 VHF high band antenna at about 250 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
---->Use only one 91XG and aim it at about 240 degree magnetic compass direction.<----
Combine the YA1713 and the one 91XG with the UVSJ and connect the AP8275.
For 1 Tv connected use No splitter.
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As always , trees and tree leaves do a good job of , multipath/reflecting , absorbing , blocking , Digital Broadcast Tv reception and so do buildings and other obstructions including your own roof and house.
It is best to install the antennas at a location that has the least amount to no amount of obstructions of any type or kind in the directions of reception including your own roof and house.
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Digital Broadcast Tv tuners can develop - Digital Glitches - that are not cleared out with simple channel scans.
Do a Double Rescan ,
http://www.dtv.gov/rescan.html