Sometimes you buy a tube that does not have the manufacturers name on it, but some letters are visible. I just found a little guide that identifies US manufacturers that made tubes for the military - JAN (or Joint Army and Navy tubes). May come in handy:
"Most tubes found today are ex-military, and carry Joint Army-Navy (JAN) designations in either a long form or an abbreviated version ahead of the tube type number. The known makers are: GE (JAN-CG or JG); Hytron (JAN-CHY or JHY); Raytheon (JAN-CRP or JRP); RCA (JAN-CRC or JRC); Sonotone (JAN-COZ or JOZ); Tung-Sol (JAN-CTL or JTL); Westinghouse (JAN-CWL or JWL)."
So, if you find a 6AK5 tube where you only can read the letters CG, you know it is a GE tube; a JTL tube means it is made by Tung-Sol etc..
Hope this is helpful in identifying tubes.
Found this from page 26 got my answer thanks mordy
Edited by MIKELAP - 9/26/13 at 1:22pm