My Soyo SYTPT3218AB LCD HDTV gets intermittent broadcast reception. I've tried numerous antennas and locations. The TV will play well on a certain station for days and then suddenly have troubles receiving and holding the signal. The weather does not seem to be a factor. Where do I start looking to solve this problem? Also, I have a TV converter box that gets all the stations and is very stable. Location is not a factor.