The Fluke Model 410B High Voltage DC Power Supply is capable of providing an output of 0 to 10, 000 vdc at 0 to 10 milliamperes. The output voltage is selected by four decade switches and a vernier potentiometer. The instrument may be operated with either positive or negative output terminal grounded, as selected by a front-panel switch. Overcurrent protection is provided to return the supply to standby operation in the event of excessive load current. 1-4. The Model 410B is a hybrid design utilizing silicon transistors for the amplifier circuitry and a vacuum tube for the necessary high voltage series passing element. A time-delay relay is incorporated in the input circuitry, which prolongs the life of the high voltage passing tube. The reference element is a highly stable temperature compensated gas tube. 1-5. The package design provides for adequate cooling at high ambient temperatures without the use of cooling fans. Rubber feet are provided for bench top operation to permit unrestricted air flow through the bottom cover air vents. The front panel is punched for mounting in a standard 19 inch rack. Side panels are tapped for Jonathan #130 quick disconnect chassis slides or other rack mounting supports.