A feasibility study was conducted to investigate the field build up process in a 36.7 m3 reverberation chamber. The time to get a steady field state in the unloaded chamber will normally be about 10 - 20 µs. However, it is of great interest to investigate which field-levels that can be expected for an ordinary radar source. The particular 700 kW S-band radar we have to our disposal has typical pulse duration of 1 µs. Maximum field strength of 35 max , R E kV/m was achieved for 309 kW input power. The voltage ratio between the ensemble maxima, VR, due to that the chamber time constant is about 10 µs and the magnetron pulse is only 1 µs, was found to be 0.54. The pulse characteristics have also been investigated when loading the chamber according to the aviation test standard RTCA DO-160. This report provides a basis on how to conduct and interpret equipment HPM testing in reverberation chambers.