This is a very common problem for indoor or window-mounted 2meter equipment, even at 1 or 2 wats. As John said, try moving the antenna, or at least the coax. If possible, put the antenna on a different wall, preferably one which is either an outside wall, or which backs up to a hallway. It is doubtful that switching from the power supply to the battery will change anything. Mike Duke, K5XU American Council of Blind Radio Amateurs