I have been getting OTA with an indoor antenna and have been able to get 2-4 of the 5 HDTV stations in my area. My NBC station suffered many dropouts with what I thought was a multipath problem due to signal jumps from 0-50% with the dropouts. The previous owner of my house had an antenna on the roof so I ran a line to my STB in hopes of alleviating the problem. The antenna is not great (18 element and approximately 50"). I can now receive all other stations without dropouts, but still have the same pattern with NBC signal strenght of 0-50% dropping in an out every 2-3 minutes. I checked antennaweb.org and all of my stations are located at 139 degrees from my location and NBC should be easier to get than CBS per their rankings. Is this multipath? Will a bigger antenna or preamp solve this or am I just in a bad location?