Check this for good reception:

Been working at my Father's house on his TV distribution. The whole
house had been re-wired with co-ax going to every bedroom. Had already
installed a new external aerial and distribution box in the loft over
a year back, but eventhough the main TV had a beautiful picture, with
all analogue and digital channels coming up, the TVs on the
distribution end were grainy. After checking every connection,
faceplate etc found I had been using the distribution cable for the
main tv not the actual aerial. Bloody thing was pulling all channels
on just the co-ax running up the wall.