(!!!) (Best Balloon 50) 450=50 Sparton Balloon tests like new 1930 era (61.5ma) (High mA and Gm) (rare 50)

450=50 Sparton Balloon tests like new 1930 era in white box - rattle inside base - dried glue particles from age - base is tight to glass

61.5mA

Gm=2480

Tested on Amplitrex

Vplate=440V

Vgrid=-66V

Good NOS mA range = 55-60ma

Good NOS Gm = 2100