The Operation of Vacuum Tubes as Class B and Class C Amplifiers

T HE majority of modern radio telephone installations in this country are designed for modulation at a low power level and amplification of the modulated carrier, so as to obtain up to 100 per cent modulation in the output stage. As far as the writer is aware there seems to be no very comprehensive material dealing with this phase of vacuum tube operation available from past publications. A treatment of the operation of such amplifiers seems particularly desirable from the standpoint of the design of vacuum tubes for such service. Some of the fundamental considerations regarding Class B or C operation were given by Morecroft and Friis,1 and later, a more complete analysis of power oscillators by Prince.2 Both of these, however, were primarily concerned with the attainment of steady output at high efficiency. Other papers 3-4-5 of more recent date have touched somewhat upon the subject.