(!) (#1 31 - BEST PAIR) 31 NOS same build 1930's - 1940 (12.8ma and 13ma)
(!) (#1 31 Pair) 31 Westinghouse NOS same build 1940 (12.8ma and 12.6ma)
31 Coronado by Sylvania engraved base used/good 1930's (11.5ma Gm=700)
31 National Union NOS 1940's (18.4ma Gm=1400) (high Ma and Gm)
31 Philco by Sylvania engraved base tests like new 1930's (12.4ma Gm=1000)
31 Raytheon engraved base used/good 1930's (9.8ma Gm=1100)
31 United licensed by RCA NOS/80% around 1940 some small getter flakes inside tube and on inside of glass (1 pair: 10.5ma and 9.5ma)
