Could this be your answer? Sylvania With roots in Massachusetts in 1901, the lamp and vacuum tube manufacturer adopted the name Sylvania Electric Products, Inc., in 1942 and merged with General Telephone to form GTE Sylvania in 1959. The Semiconductor Division based in Woburn, MA developed high frequency transistors and introduced the first commercial TTL family in 1963. This doesn't say where they were making the tubes in MA, but Sylvania was definitely one of the 5 leading US manufacturers of tubes--others were RCA, GE, IMAC, etc. My husband tells me that during WWII there were other small companies around the country who operated as a joint venture with the military to fill the need and tubes made were issued a JAN # (Joint Army Navy). You might possibly check with a local museum there or research librarian. Sandy Sandra Lee Blakley 336 South 30th St. Philomath, OR 97370 541-929-2259 --------------------------------- Never miss a thing. Make Yahoo your homepage.