High power RF Microwave amplifiers are becoming more important as the telecommunications, defense and aerospace industries' demands develop. GaN on SiC technology offers higher power and better form factors for these applications compared to GaAs. In addition, SiC provides better mechanical properties and thermal performance. Design, manufacturing and measurements of a S-Band Power Amplifier by using a GaN discrete bare die transistor are presented. GaN on SiC technology, fabrication process, amplifier fundamentals and design steps are explained in detail. PCB laminate properties, manufacturing, wire bonding and importance of heat management are explained. Design, tapeout, characterization of a fabricated HEMT and its packaging are also mentioned. Power amplifier's small-signal gain of 14.5 dB is measured at center frequency. 41.5 dBm RF power at P6dB is measured at 200 μs pulse width 10% duty cycle at 3 GHz, reaching a power density of 5:4W=mm. Small-signal gain, IP3 measurements under different biases, AMAM and AM-PM distortions are also investigated in detail. EM simulations are performed in Keysight ADS design environment. Amplifier design is based on small-signal and loadpull measurements. De-embedding of fixture effects during HEMT characterization and their models are also investigated. Another hybrid amplifier design by using a packaged commercial GaN on SiC bare die power HEMT is also presented. Small-signal and power measurements are also offered.