71A Raytheon 4-Pillar box-plate used/good 1930”s (23ma)

71A Raytheon 4-Pillar box-plate used/good 1930”s engraved base

23ma

Gm=1700

SINGLE TUBE, NOT A PAIR

Tested on Amplitrex

Vplate=180V

Vgrid=-38V

Good Ma = 20ma

Good Gm = 1600-1700

(71A=5V @ .25A Filament)

Mu=3

Rplate=1.82Kohms

Rload=3Kohms