[imported_The Vibesman]

Once you find a frequency with nothing on it you should be able to leave it on that frequency indefinitely and have no problems. The broadcast unit doesn't move in relation to the antenna so there's usually not a problem. Sometimes if it falls between the seats or is low on batteries I get some static, or if the frequency I'm on is a little "busy." But I have a cheap one with only 4 pre-set FM frequencies I can use. It was $20. When you get up to the $50 range you can tune just about any frequency on it. If you have a lot of radio stations in your area it might be worth it to go to the $50, I don't know. I live in the Boston area and have been thinking of upgrading, as there are a ton of radio stations up here, and no real clean stations on the presets of my unit, (only broadcasts to 88.1, 88.3, 88.5, and 88.7 or something like that.) But even with that, I still usually get fine reception.