You can select the ALC mode of operation—internal or fixed gain (ALC off). In addition, the signal generator provides a decouple function that allows decoupling of the step attenuator (if equipped) from the level setting. The ALC LOOP CONTROL settings menu is shown in Figure: ALC Loop Control Menu.

Press the ALC Loop Control SOURCE button shown in Figure: ALC Loop Control Menu to access the ALC leveling modes.

Press: ALC | LOOP CONTROL | SOURCE.

This is the normal default leveling mode. Output power is sensed by the MG362x1A’s internal detector. The detector output signal is fed back to the ALC circuitry to adjust the output power level. Internal ALC is selected from the leveling menu.

To select internal ALC, press Internal. Pressing one of the other leveling menu soft keys External Detector or Fixed Gain will turn off internal leveling.

In external leveling, the output power from the MG362x1A is detected by an external detector or power meter. The signal from the detector or power meter is returned to the ALC circuitry via the rear panel EXT ALC IN connector. The ALC adjusts the output power to keep the power level constant at the point of detection. To select the external ALC input from an external detector, press ALC | SOURCE External.

In the fixed gain mode, the ALC is disabled. The RF level DAC and step attenuator (if installed) are used to control the relative power level. Power is not detected at any point and the absolute power level is uncalibrated. After fixed gain mode is selected, the attenuator (if installed) is decoupled and the RF level DAC value is displayed.

The ALC power slope function lets you compensate for system, cable, and waveguide variations due to changes in frequency. This is accomplished by linearly increasing or decreasing power output as the frequency increases. The example shown in Figure: ALC Power Slope Example, displays how the power slope function provides you with the ability to set both the power slope and the pivot point. The ALC loop menu lets you activate the ALC power slope function.

Manual setting of the LEVEL DAC. This setting is used in conjunction with the manual attenuation setting to allow user control of the output power when in ALC Fixed Gain selection. The RF level DAC adjustable range is from a minimum output of 0 to a maximum output of 65535. To select the Fixed Gain ALC input from an external detector:

Press: ALC | SOURCE | Fixed Gain

Edit the level DAC by pressing LEVEL DAC, and use the control keys, rotary data knob, or enter a new power level DAC value using the keypad and press ENTER.

Used when the SOURCE is set to External or Fixed Gain. Sets all the Digital Step Attenuators in the Digital Down Converter, Switched Filter Module, and Frequency Extension Module to 0 for High Range and 10 for Low Range. Can be used when the RF step attenuation is manually set to 0 dB, allowing for a 10dB extension of range in high level range.