This paper reviews developments in X-band power combiner designs . A compelling application combines outputs of multiple solid state power amplifiers (SSPAa) into a single higher power output to compete with a traveling wave tube amplifier (TWTA) with about the same total output power. Modern SSPAs have system design and maintenance advantages over TWTAs that are attractive to exploit. The paper compares a large number of X-band radial power combiner designs and discusses the potential for many of the combiner design approaches to be useful at different frequencies.