The Model 711A Power Supply is a general-purpose low-power dc and ac voltage supply particularly suited to powering experimental setups, By means of the facilities provided by the Model 711A the following voltages are made available at the output terminals on the control panel: Unregulated ac: 6. 3 volts, 3 amperes maximum load current (two supplies) or 6. 3 volts, 6 amperes maximum load current (one supply) or 12.6 volts, 3 amperes maximum load current (one supply, tapped at 6. 3V). Regulated dc: 0 to 500 volts, continuously variable; maximum output load current, 100 ma. NOTE: Insulation within the Model 711A permits operating the dc output voltage as much as 500 volts from chassis ground so that two Model 711A Power Supplies may be operated in series to obtain 1000 volts dc output while each instrument chassis remains at ground potential. The dc output of the Model 711A has high stability; for line voltage variations within rated limits, the level of the regulated output will vary less than 0. 5% or 1 volt (whichever is greater), and from no load to full load the level of the output will vary less than 0.5% or 1 volt (whichever is greater). Ripple will be less than 0. 001 volt. While the internal impedance of the Model 711A will vary both with the dc load current and the frequency of any reflections from the equipment being powered, the internal impedance of the Model 711A will be less than 10 ohms with any load current and at any frequency up to a few megacycles. The dc output is continuously monitored by two meters, a voltmeter and a milliammeter. A low and high range are provided for each meter so that low values of voltage and current may be read accurately. The power supply is protected from input or output overload by (1) a fuse in the line-voltage input circuit and (2) a relay, in the main positive bus, which operates at overload current to interrupt conduction through the regulator.