The starting conditions for the O-type backward-wave oscillator are computed for large values of C, QC and d, using both digital and analog methods. A general method of solving complex polynomials called the “downhill” method is applied both to the secular equation and then to the RF voltage equation to obtain starting conditions. The analog computer is used to solve simultaneously, by trial and error method, the linear circuit and ballistic differential equations. The analog method is applied to the modulated BWO in order to determine the effects of modulations on the starting conditions. Extensive calculations of BWO starting conditions have been made for a wide range of C, QC and d. Copyright © 1961—THE INSTITUTE OF RADIO ENGINEERS, INC.