I had a 30+ year old amplified 20" saucer Shakespeare antenna that flew off the very top of my mast on my Grand Banks 42 classic during hurricane Sally...  I replaced it with a "Shakespeare Seawatch 19" Marine Tv Antenna - 12vdc - 110vac".. When I installed it, I did not use the new amplifier; I just plug the coax into the old amplifier...  When I scan channels (25 miles from Pensacola Fl and 45 miles from Mobile AL) on the TV, I get 30+ channels from both of those cities... lots of shopping and religion but I also get the "sub channels" (like 3.1, 3.2, 3.3)..