If you are transmitting from a mobile in your Jeep, operating at, oh I dunno, say 10 watts or more, chances are the handheld radio is being desensed. (Desensitization - The reduction of receiver sensitivity due to overload from a nearby transmitter.) The only cure to operate this way is to move the handheld radio away from the Jeep while transmitting, which probably defeats the purpose of what I think you're trying to accomplish. The further away you get, the better it will sound. The other alternative is to change the mobile radio to a radio that can be programmed for an odd repeater split.