I have a Glomex that came with the boat and has never worked.
Have no clue what to get so comments appreciated too.
FWIW, before I changed to the 14" Glomex, I had some useful back-and-forth with their tech guy via e-mail. What dB gain I should be seeing, what gain to expect with the new one, whether I needed a new amplifier too, or not, how to insert a new A/B switch into the system if necessary, better UHF reception after the HD switchover, vertically polarized signals, etc. Very helpful.
I was actually trying to figure out why I couldn't get very consistent reception in Charleston, given broadcast stations there were closer to us than almost all of the "local" broadcasters are here at home. (Turns out it was likely more about interference with all the sailboat masts around us down there...)
As we talked through it, it became apparent it would be an easy switch for me, no new COAX run required, no new mount base and so forth... just off with the old, on with the new... so I thought I'd give it a go.
FWIW, I also used these sites -- both before and after the change -- to learn more about the details behind why I can or cannot see some stations from our home marina:
TV Fool
https://www.fcc.gov/media/engineering/dtvmaps
At least I came to understand more about why our reception is what it is. (I have some background in radio theory; just didn't know details about the various TV transmitters in a given area and what that means relative to where we are at any given time.)
Anyway, after looking inside the old one, turns out, there's not much that could go wrong with the antenna itself (although its not impossible). That's probably the same with Shakespeare and other various brands, too. Seemed more likely that if I were to be having a problem, it would be in the COAX, or the various connectors, the several splitters, or the amplifier.
What I'm leading to is that you might try a test. Hook your Glomex directly to your TV, see what happens. Then connect it directly to your amplifier and then to the TV, and see if the gain control adds anything. (If you don't have it, there's a nifty tool they supply to connect the COAX inside their hollow mount tube if you need to put it back together afterwards.)
I'm thinking you might get lucky and find that the problem isn't the antenna but somewhere else in your system... and maybe relatively easily correctable without a new antenna. And if there is a problem somewhere that not with the antenna, just replacing the antenna with another (no matter the brand or type) maybe won't improve anything anyway.
-Chris