I have a 1951 (the year I was born) Weston model 798, type 5B tube tester with its manual and tube charts but no updated (post-1951) tube charts. does anyone have updated tube charts for this or know that they exist? I wrote to Weston about this many years ago (70's?) and was simply told the 798 was obsolete and nothing was available. 73 de W3NU