Ah just the thread I am looking for! A newbie question! I have a dual horn dish, one cable runs to a new 505 for HD. Another cable from the dish runs to a basement where there is an old General Instruments (?401). All was working fine untill I added a 500 to the basement with a splitter on the feed, one to the 401 and one to the 500, not all the channels work etc Do I need a special kind of splitter, a signal amp, or do I have to run a third line from the dish to to the third receiver,the biggest job?