changed out that last 12 feet of RG59 with RG6

[DavGoodlin]

I had similar experiences, and use all my old RG 59 for FM or channel 3/4 from the DTV box.

30+ years ago in my antenna-installation heyday, RG6 was not commonly used other than by cable companies, primarily becase it was available as quad-shield, to keep cable from radiating.

Preferring Belden foam-core twin-lead types over RG-59, it often made the difference between getting deep-fringe UHF and not getting it. Of course, twin lead had to be carefully run using stand-off insulators and would get more lossy than coax when it was wet.