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
yogiboy
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.
Thanks for the info