Th-e California Instruments’ Model 848TCM AC Power Controller is designed as a plug-in controller of frequency and waveform amplitude. The 848TCM will plug into and obtain power from all California Instruments AC Power Sources. The frequency and amplitude are locally controllable by a front panel keyboard or remotely programmable by the IEEE-488 interface. Option PC for the associated power source is required to mount the IEEE-488 interface connector in its rear panel. The output of the Model 848TCM provides three-phase variable frequency and amplitude drive for the power source, The remote sense input monitors the voltage across the load. The voltage at the sense point will be maintained by the Model 848TCM to be equal to the programmed value. In the event that this voltage cannot be maintained, the Model 848TCM will automatically set the output voltage to zero volts and then step the output voltage in five volt increments to the programmed value. If the programmed voltage is still not maintainable, the Model 848TCM will set the programmed voltage to zero volts and display an error message coincident with the phase or phases generating the fault. The Model 848TCM employs digital techniques for control of the output frequency. A crystal controlled oscillator serves as the clock for the digital frequency generator that controls the output frequency. This circuit configuration provides the same long-term frequency stability as the crystal time base. The crystal time- base is adjusted at the factory for a frequency accuracy of ±5 ppm. The output frequency will, therefore, be equal to ±5 ppm of the programmed frequency* The Model 848TCM is capable of operating from 45 Hz to 9999 Hz, 999.9 Hz or 99.99 Hz in 1 Hz, .1 Hz or .01 Hz steps depending on the frequency range (see paragraph 1.3). The low end of the frequency range is limited by a frequency detector to 45 Hz. The high end is factory adjusted to the upper full power frequency limit of the associated power source. If an attempt is made to program the frequency outside these frequency limits the amplitude will default to zero volts and the display will show the error message E 71. The Model 848TCM must be used on the 135 volt range when used with a power source on the 120, 130 or 135 volt range. It must be on the 2 70 volt range when used with a power source on the 240, 260 or 270 volt range.