HP 22A, 83620A, 24A manual Operating and Programming Reference A-7

(POWER LEVEL), the ALC level and attenuator are set automatically to provide the most accuracy for the power requested.

Uncoupled Operation. In some applications it is advantageous to control the ALC level and attenuator separately, using combinations of settings that are not available in coupled operation. In uncoupled mode (Uncoupl Atten ), when the desired power output is set via (POWER LEVEL), only the ALC level is changed. The attenuator setting is changed via Set: Atten.

One use of uncoupled operation is power sweep, where the output power linearly tracks the sweep voltage ramp. The synthesizer can generate power sweeps of up to 40 dB, depending on frequency. The power at the start of the sweep is set via (POWER LEVEL) (coupled operation) or by a combination of POWER LEVEL and Set Atten (uncoupled operation). The sweep range is entered by selecting Power Sweep. If the sweep range entered exceeds the ALC range (stop power greater than maximum available power), the UNLVLED warning message appears at the end of sweep. No warning is given at the time of entry. If the start power is entered when the synthesizer is in coupled operation, the ALC level is set no lower than -10 dBm, limiting the available power sweep range. Using uncoupled operation and setting the ALC level to -20 dBm gives an additional 10 dB of sweep range.

External Leveling - Leveling Mode Normal ,

Leveling Point ExtDet or PwrMtr or Module

In externally leveled operations, the output power from the synthesizer is detected by an external sensor. The output of this detector is returned to the leveling circuits, and the output power is automatically adjusted to keep the power constant at the point of detection. Figure A-2 shows a basic external leveling arrangement. The output of the detected arm of the splitter or coupler is held constant. If the splitter response is flat, the output of the other arm is also constant. This arrangement offers superior flatness over internal leveling, especially if long cables are involved. Flatness may be improved with user flatness correction ((FLTNESS ON/OFF), Fitness Menu ) applied at the external leveling point.

HP 8360	Operating and Programming Reference A-7
User’s Handbook