O-MBK with Partially Grounded Depressed Collector

New results are presented for the development of a 3 MW highly-efficient radio-frequency (RF) source at 1.3 GHz. The project's ultimate goal is to equip the existing tube with a partially grounded depressed collector in order to boost its efficiency to at least 73 %. The tests of this device in its original configuration are not yet completed. A limited 2-week campaign at Communication & Power Industries, LLC yielded 3MW at nearly 60% of efficiency in narrow 15 microsecond pulses. The next stage is to test the device and optimize it to achieve 62-63% in efficiency in the full pulse at 1.5 milliseconds. The preparations are almost complete to do these tests at SLAC National Accelerator Laboratory, End Station B. The results will be presented.