Abstract: The development of 3mm wavelength generator wit h high frequency stability and rather high power is considered.A brief review of the theory on magnetron synchronization is gi-ven.The possibilities for improv ing synchronization parameters are studied.Special attention is paid to the exte rnal supplementary feedback circuits.The calculating results of magnetron genera tor parameters with external supplementary feedback in 3mm wavelength range and experimental results of similar generator in 3cm wavelength range are given.The perspective of the application of external supplementary feedback circuits is gi ven.