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Make sure the UHF Bowtie Loop Ends are connected to the bolt studs where the the matching transformer (balun) connects , if the UHF loops are not connected , reception of the UHF channels will not be good.
Make sure the feed wires that connect the VHF metal reception elements are connected correctly , so that the signal received by the metal reception elements can flow to the connections where the UHF Bowtie and matching transformer connect.
www.antennacraft.net/Manuals/HBU_web_manual.pdf
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Also to Prove Reception , connect a NEW Matching Transformer
to the antenna.
And also connect a NEW Continues Length of RG-6 Coax to the NEW Matching Transformer.
And Run the NEW Continues Length of RG-6 Coax through a open door or window dirrect to 1 Tv.
No splitters , No couplers , No etc. .
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Digital Tuners can develop -Digital Glitches- that are not cleared out with simple channel scans.
To clear tuner do Double Rescan.
www.wchstv.com/DoubleReScanAlert.pdf
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Also did you follow directions about install the antenna at a location avoids obstructions in the direction paths of reception.
Avoiding obstructions of reception is Actualy Important.