I'm in Largo about 23 miles from the 575 and have no problem hitting it with my KG UV-9g . I do have to be outside to do it.
Have you tried to hit the TAMPA BAY 700 repeater which is a couple of blocks away from 575 , also in downtown Tampa?
I've added a J-pole antenna on a 20 ft. mast so I can hit the 575 from my workbench in the garage. I don't have any luck with the 700 repeater but you might see if you can hit that one , Bye the way, I also have a Baofeng BF-F8HP and it also can hit the 575 repeater, I did add a Nagoya 771G antenna to the Baofeng and it seems to help. Good luck and hope you find the right combination to hit the 575
