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(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
User’s Handbook
Operating and Programming Reference
A-7