I was helping a friend set-up his new HT system, when I noticed that there was only one coax coming out of the wall. Somewhat perplexed, I contacted the people who installed his antenna (analog) and his DSS dish. They told me that they are running both on the same RG6 coax. In fact, he has this distributed to three other sets in his home. I'm curious, is this acceptable or should there be separate coax for each?