I have just purchased a 2007 Sonata with about 80k miles. Car is great except the radio reception is very weak, especially AM. Talk stations I used to listen to in my Ford are now not even audible. Is this a common problem? I have added an AM antenna booster that helps just a little bit, and I am considering adding an external antenna, or possibly replacing the XM antenna with one that has a verticle pole antenna such as most GM vehicles. Anyone tried this approach?

 

Even though you added an antenna booster I suspect that the factory antenna booster is the problem. If it's unplugged or not working then it would prevent your radio from getting radio signals... and the booster that you added isn't getting a signal to boost.

Look at the window where the antenna is embedded and see where the lines enter the car. The factory antenna booster will be located nearby...probably hidden behind the C pillar. I'll bet it's unplugged, but if everything looks ok then disconnect it and install the booster you bought in it's place.

 

Try removing the tape from tonge that radio sits on. The unit it's self needs be grounded. Remove tape or add extra small ground wire from unit to ground.