cb installation question

I have a 1994 Ford Ranger truck. I just installed a brand new cb and antenna. I have the power hooked stright to the battery and the ground to the ground on the battery. I can receive perfect, I can transmit perfect with car only idling. When I drive and try to talk, all that others can hear is a high pitched squeal. I tried a friends cb in my car with the same results. I have installed cb's in the past and not come accross this situation. Any help would be greatly appreciated.

all of the cb installs i've seen tap into the fuse panel for a power source, never directly to the batt.

I tapped into the fuse box first, with the same result. So I thought I would try a direct power source, same result again.