Later today after work I am going to put the RG6 straight into the TV as it has a built in tuner and see what the reception is like.
It's likely that your TV has a built-in signal level meter, so note the signal levels of each channel. Mine are all in the 87% to 99% range with my 1950's era attic antenna on my TVs and my Tivos.
Randy URC MX-890, MX-780, MX-450, R40, MX-500, Sony XBR-55X900E, Panny TC-P55ST60, Tivo Roamio Pro & Premiere & OTA, TWC Arris DVR, Onkyo 333 AVR, Roku Express 4K, Panasonic Blu-Ray