Power-One Inc. wrapped up what is chief executive called a challenging quarter with a net loss of $6.5 million. The fourth quarter financial performance of Camarillo-based manufacturer of power conversion products was affected by factory inefficiencies, logistics costs and $1.8 million in legal costs associated with a patent lawsuit. The $6.5 million net loss, or a loss of $0.07 per diluted share, on revenues of $132.2 million for the quarter ending Dec. 31 was lower than the net loss of $14.2 million, or a loss of $0.16 per diluted share, on revenues of $116.2 million for the same period in 2006. While sales increased for the year, not all with the company went as planned, said CEO Bill Yeates. The high priority is to improve gross margins and steps taken to accomplish that include closing facilities in Texas and Hungary and increase use of the facility in China, Yeates said.