6A387 A
Given a vacuum tube of the following characteristics: plate voltage 1000 V, plate current 127 ma, filament current 5.4 amp, mutual conductance 8000 microvolts, and amplification factor of 25.  What is the correct volume of negative grid bias for Class B amplifier?
A.40 V
B.50 V
C.30 V
D.60 V
