(!) 448A Western Electric smooth top used/strong 1966-1970 (1 pair: 37ma and 40.5ma) (Matched on Amplitrex)

1 pair) 448A Western Electric smooth top used/strong 1966 and 1970 – reboxed

1 tube) 37.9ma Gm=27,600

1 tube) 40.5ma Gm=26,800

Amplitrex Test Data:

Vplate=135V

Vscreen=135V

Vgrid=-2

Good Ma range 20-30ma

Good Gm = 23,000 – 27,000

DIY pentode