A microwave generator system for use in a microwave plasma enhanced chemical vapour deposition (MPECVD) system, the microwave generator system comprising: a microwave generator unit configured to produce microwaves at an operating power output suitable for fabricating synthetic diamond material via a chemical vapour deposition process; a fault detection system configured to detect a fault in the microwave generator unit which results in a reduction in the operating power output or a change in frequency; and a re-start system configured to restart the microwave generator unit in response to a fault being detected and recover the operating power output or frequency in a time period of less than 10 seconds after the fault in the microwave generator unit which caused the reduction in the operating power output or the change in frequency.