A radio transmitter and method controls efficiency of each of a plurality of power amplifiers that amplify a corresponding one of a plurality of radio frequency signals for a beamforming transmission by a corresponding one of a plurality of antennas. Each of the plurality of power amplifiers is controlled to operate with one or more operating parameters that optimize the efficiency for an output power level of corresponding ones of the radio frequency signals. Transmit weights for transmit signals are determined and updated on a per-packet basis.