A 4 way splitter reduces signals at the output ports by 75%. You should still replace the antenna since you have little fade margin (or none) on some channels, and may still be missing others. The (poor) preamp in your Terk antenna can't handle a 4 way splitter most likely. With only a few exceptions, antennas with build in preamps, have poor preamps. The Hopper 3 probably has a poor tuner (not familiar with them) that performs poorly compared to many TV tuners. You have to hit it with a good quality signal. A high end antenna on the other hand, with quality preamp should have no problem driving a 4 way splitter, as is.