In this paper, an X-Band power amplifier prototype is designed over the frequency band of 8 GHz-10 GHz with mixed lumped and distributed elements using so called "Yarman and Fettweis Double Matching-Parametric Approach" and "Design with Mixed Elements Technique' developed by Yarman, Aksen and Fettweis. The proposed algorithms employ three major steps. In the first step, lumped element prototype is generated employing the Fettweis representation of Brune functions. In the second step, lumped element prototype is replaced with its almost equivalent mixed element counterpart. In the last one, electric performance of the overall mixed element amplifier is re-optimized for the maximum power output and the flat transducer power gain. In the course of amplifier design, Cree's 70W GaN HEMT transistor CGHV1J070D is utilized. It is shown that the mixed element power amplifier is capable of delivering 50 W continuous power with 50% power added efficiency over the frequency band of 8 GHz-10 GHz.