The Model 317 Power MOSFET Modulator, Magnetron Transmitter is designed to operate magnetrons up to 75 kW. The RF pulse is continuously variable, and the pulse width is determined by the magnetron capability. The Model 317 Modulator is not damaged by magnetron arcs. Arc energy to the magnetron is limited which actually helps to clean-up an arcing magnetron. The Model 317 Modulator is a proven, reliable design which fills a need for an inexpensive, versatile transmitter with excellent RF output fidelity. The modulator HVPS is a very efficient, duty cycle regulated DC to DC converter design. A higher power version of the Model 317 (designated Model 327) is available for operation of magnetrons up to 150 kW. Photographs of the output spectrum and detected RF are included.