(!!!!) (Recommended Pair) 311B Western Electric NOS 1973 and 1975 (35.2ma and 36.4ma)

1 pair) 311B WE NOS “”O”” getter halos in white boxes

1 tube) 36.4ma and Gm=3250 (1973)

1 tube) 35.2ma and Gm=3150 (1975)

Tested on Amplitrex

Vplate=180V

Vscreen=135V

Vgrid=-15V

Good Ma = 30ma

Good Gm = 2900