DATE CODE ON SYLVANIA TUBE

I have a sylvania 6189w tube,the numbers from top to bottom are 6727,does anyone know when this was made?
THANKS

yogiboy03-21-2009 5:58pm

albertporter Details Discussions Posts This discussion Message User 4,949 posts 03-21-2009 at 07:03pm Copy Comment URL Report Comment Edit Delete Your tube is the Military version of 12AU7 and if it follows numerical code of similar tubes manufactured in 1950's and 1960's, the "67" is the year and "27" is the week.
yogiboy OP Details Discussions Posts This discussion Message User 5,454 posts 03-21-2009 at 07:23pm Copy Comment URL Report Comment Edit Delete Thanks for the info