A multi-channel fixed wireless terminal (14) is implemented using a gain controller (34) for controlling the gain of each of a plurality of transmission channels. The gain controller (34) includes an averager (62) for receiving and averaging gain control signals (58a-58d) for each of multiple transmission channels to generate an average gain control signal (48). In addition, differentiators (70a-70d) generate respective differential gain control signals (74a-74d) for the multiple transmission channels from the respective gain control signals (58a-58d) for the multiple transmission channels and the average gain control signal (48). A plurality of adjustable amplifiers (72a-72d) controlled by the respective plurality of differentiators (70a-70d) amplify signals transmitted over the multiple transmission channels and input thereto to maximize respective signal to noise ratios of the signals. Through implementation of the gain controller (34), the multi-channel fixed wireless terminal (14) may be implemented with only a single transmitter (38).