(!!!!) (Recommended Pair) 6F6G Marconi Spain NOS 1940's (33.2ma and 34.2ma)
(!!!!) (Recommended Pair) 6F6G Marconi Spain NOS 1940's (37.5ma and 39ma)
(!!!) (Best Pair) 6F6GT Tungsol NOS 1954 (34ma and 34.5ma)
(!!!) (Best Single) 6F6G Marconi Spain NOS 1940's (35.8ma)
(!!!) (Best Single) 6F6G Marconi Spain NOS 1940's (44ma)
(!!!) (Best Single) 6F6G Tungsol NOS 1950 (37.2ma)
(!!!) (Single) 6F6G Marconi Spain NOS 1940's (35.2ma)
(!!) 6F6GT Tungsol NOS 1953 (37.5ma)
(!) 6F6G Sylvania Philco NOS 1949 (36.5ma)
(!) 6F6G=VT-66A Sylvania used/tests like new 1940's (45ma)
1613=VT-175=6F6 RCA NOS 1963 (42ma)
1621=6F6 selected for long life RCA NOS
6F6 GE metal can NOS 1954 (35ma)
6F6 Sylvania metal can NOS 1950's (37.5ma)
6F6=VT-66 RCA metal can NOS 1940's (40.5ma)
6F6G National Union black plate NOS 1951 (40.5ma)
6F6G National Union used/good mid-1940's (47ma)
6F6G RCA Cunningham used/good 1947 (31ma)
6F6G RCA NOS 1949 (35.8ma)