I have this one, but don't expect any tech support from these folks - out to lunch all the time.
HD Stacker TV Antenna
The connections are important, don't go too tight with your cable loop radius, and loop them before a connection so they don't bind up.
I've found that mast height, antenna ground, mast ground, and cable ground are all improvements and devils in the detail.
I have found this forum below helpful, but a bit slow at times.
http://forum.tvfool.com/index.php