+=>
Most Likely the added section of coax is bad.
The coupler that connects the coaxes together is bad.
The splitter is bad.
The etc. is bad.
To Prove Reception , connect a New Continues Length of coax to the DB8e antenna and run the New Continues Length of Coax through a open door or window direct to 1 Tv.
No couplers , No splitters , No etc.
It is the DB8e antenna , A continues lenght of New Coax , Direct to the Tv.
As always , trees and tree leaves , plants and plant leaves, have a Negative Effect on Broadcast Tv Reception.
Some and not all Negative Effects are.
Absorbing and Blocking Reception.
Multi-Path Reflecting Tv Signals Bouncing All Around.
The Best Practice for Reliable Reception 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/s of reception.
--------
Digital Tv 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