i have charter cable and dish.my dish locals are sd but i can get my cable locals in hd if i just run the cable to the tv without going through the digital box.i scan and hd chanels come up as 3-1,6-1,10-1.it won't work if i go through the digital box,i imagine because the regular box is sd.i don't have a hd subscription or a hd box so how is it i get the hd"s?