6EW7 RCA BIG BOTTLE black plates NOS 1961 era (5.4/42ma)6EW7 RCA BIG BOTTLE black plates NOS 1961 era 1 triode section) 5. 3ma Gm=2000 1 triode section) 42ma Gm=6900 Tested on Amplitrex AT1000 Section 1 reference = 4 6ma and Gm=1700 2100 Section 2 reference = 45 50ma and Gm=7000 8000 (6EW7 is a close substitute to the 6DE7) Woo Audio 6 Woo Audio 6 SE RCA made skinny bottle 6EW7 Sylvania made FAT BOTTLE 6EW7