TOKYO, Feb 28 (Reuters) - Japan's Nikkei share average dropped for a third day on Friday as investors remained cautious amid tensions in Ukraine, while a stronger yen weighed on risk appetite and dragged down exporters. The Nikkei ended 0.6 percent lower at 14,841.07 in choppy trade after falling as low as 14,735.52. It fell 0.2 percent for the week and dropped 0.5 percent for the month. The broader Topix index slipped 0.5 percent to 1,211.66. The JPX-Nikkei Index 400, an index launched this year comprising firms with high return on equity and strong corporate governance, dropped 0.3 percent to 10,971.80.