H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
H03F1/08—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements
H03F1/14—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements by use of neutralising means
H03F1/16—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements by use of neutralising means in discharge-tube amplifiers