I purchased a new radio/cd player 6 months ago. Sony cdx-ca710x. It was working fine until last week. For some reason, I cannot tune into any local radio stations. I live in San Francisco, and when i am in the city, and can tune in perfectly to all stations. When I drive to the suburbs i cannot receive any stations. Any idea on what is going on? Can I fix this myself or do i have to take it into the shop?