Here are stand alone Tuners/Recorders that have Better Tuners.
http://www.epvision.com.
http://www.channelmasterstore.com.
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When Testing reception Without antenna system amplifier.
Disconnect and Remove All parts of the amplifier.
Disconnect and Remove the preamplifier unit.
Disconnect and Remove the power injector.
Disconnect and Remove the power supply.
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As always , trees and tree leaves , plants and plant leaves , have a Negative effect on Broadcast Tv Reception and so do buildings and other obstructions including your own roof and house.
The Best Practice is to install the antenna at a location that has the least amount to no amount of obstructions of any type or kind in the direction of reception.
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As a Test for reception.
Recommend install a NEW coax from the antenna Directly to 1 Tv.
No amplifiers , No splitters , No couplers , No nothing.
It is the antenna , the New coax , the Tv/tuner.