Hello, Bill:
The ANT751 doesn't have enough gain for your signals. NBC has a Noise Margin of only 8.7 dB. I suggest a larger antenna like the Winegard HD7697P aimed at 221 degrees magnetic by a real pocket compass and a Channel Master 7778 preamp.
The splitter goes after the power inserter. If you need more signal substitute a Channel Master 3414 amp for the splitter.
The coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference. For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge, but the system will not survive a direct strike.