(!!!!) (Best Pair) 311B Amperex made in Russia NOS 1977 (34.2ma and 34.5ma) (very good construction)

1 pair) 311B Amperex made in Russia NOS 1977 large getters – excellent condition

1 tube) 34.2mA Gm=3000

1 tube) 34.5mA Gm=3050

Tested on Amplitrex

Vplate=180V

Vscreen=135V

Vgrid=-15V

Good Ma = 30ma

Good Gm = 2800-2900