Japanese pubcaster NHK has developed a device that enables high-definition TV programs broadcast in different formats to be viewed on the same receiver.The converter means that NHK has removed the biggest obstacle facing the export of Japanese-manufactured HDTV sets, which are designed to receive NHK’s MUSE system of HDTV broadcasts (1,125 lines at 60 Hz) and therefore cannot receive Europe’s Eureka format (1,250 lines at 50 Hz). NHK officials say it will be another two years before the 440-pound converter is reduced to a more manageable size. But the development proves that perfect conversion is possible. So even if, as is expected, the U.S. adopts a third HDTV format next year, Japanese manufacturers could still sell their sets (with converters) to the U.S. All previous attempts to convert images between the two existing systems resulted in reduced picture quality. The converter is being constructed for NHK by Oki Electric Industry. The rising popularity of HDTV broadcasts in Japan, where more than 5,000 receivers (at a minimum cost of $ 8,000) have been sold this year, has prompted the seven HDTV broadcasting companies to make more programs available at night. Next month programs will start every day at 1 p.m. and continue until 9 p.m. (instead of 7 p.m.).