Abstract: A housing encloses a tumbler-type microwave opaque drum operating on a horizontal axis. A microwave power supply is mounted on the housing with the output directed axially into the drum. The drum has an inner coating or layer of microwave insulating material to reduce arcing of microwave energy between the drum and metal articles tumbling therein. A rear portion of the drum has a microwave-transparent perforated wall supported therein which keeps tumbling articles out of the near field of the output of the power means. The drum and the housing have an overlapping microwave seal therebetween to maintain the microwave energy efficiently in the drum. A forced air arrangement is provided for circulating air through the drum and also to pick up heat from the power supply to increase the vapor carrying capabilities of the forced air and to cool the power supply.

Abstract: A hollow tumbler-type microwave opaque drum is mounted on the horizontal axis in a housing and is driven rotatably for tumbling articles laterally across the interior of the drum. A microwave power unit is disposed with the output thereof directed axially through the rear of the drum for engaging articles tumbling in the drum. The microwave unit is disposed in an auxiliary housing and an arrangement such that a blower can circulate air around the power unit for cooling it and also for moving such air through the cavity of the drum for carrying away vapor which has been removed from the articles. In a second embodiment of the invention, the rear mount power unit can be used in combination with a front mount power unit to double the capacity for removing mositure from articles tumbling in the drum. The front mount power unit also is associated with a passageway arrangement for cooling the power unit.

Abstract: A housing rotatably supports a hollow drum on substantially a horizontal axis whereby articles to be treated tumble around the interior of the drum when the latter is rotated. A microwave power mechanism, such as a magnetron, is provided in a door for the housing and has an output portion thereof directed into the drum for heating and drying articles tumbling in the drum. An output portion of the microwave power mechanism has a dielectric dome-like shield mounted over it for deflecting tumbling articles away from such output. A forced air system is provided for ventilating the interior of the drum, and such system includes a passageway extending adjacent to the power mechanism so that such ventilating air also cools the power means.