08 avenger aftermarket radio issue

a buddy of mine had CC install an aftermarket radio with XM and all that jazz for him, and his radio reception on FM was cut to about 60% and AM to ZERO! not the most familiar with dodge's radio setups, but i figured the antenna is powered. CC said the radio he bought does not have seperate outs for fm and am antennas, but either way there shoud be a way to power the antenna. my question is, can i just splice in somewhere to power antenna, does it need 5V, 12V, or is it something regulated by the factory radio and he is screwed? and he also gave the factory radio away....so i am really stumped. Thanks in advance

45 views and no replies.....does someone need more info or just nobody knows? any ideas?