7-9
Operating Concepts
Output Power
Output Power

Understanding the Power Ranges

The built-in synthesized source contains a programmable step attenuator that allows you
to directly and accurately set power levels in twelve different power ranges. Each range
has a total span of 20 dB (15 dB, 8722ET/ES). The twelve ranges cover the instrument’s
full operating range. In addition, some amount of overrange and underrange is permitted
beyond the stated limits. Performance outside of the range limits varies from one analyzer
to another and is not specified. A power range can be selected either manually or
automatically.
Automatic mode
If you select , you can enter any power level within the total
operating range of the instrument and the source attenuator will automatically switch to
the corresponding range.
Each range overlaps its adjacent ranges by 15 dB, therefore, certain power levels are
designated to cause the attenuator to switch to the next range so that optimum (leveled)
performance is maintained. These transition points exist at −10 dB from the top of a range
and at +5 dB from the bottom of a range. This leaves 10 dB of operating range. By turning
the RPG knob with being the active function, you can hear the attenuator
switch as these transitions occur. See the specifications and characteristics chapter in the
reference guide for the analyzer’s power limits.
Manual mode
If you select , you must first enter the power ranges menu and
manually select the power range that corresponds to the power level you want to use. This
is accomplished by pressing the softkey and then selecting one of the
12 available ranges. The active power will always be reset to be within this range. In this
mode, you will be able to select power levels above or below the range limits. The factory
limits on setting power level are +6 dB above the maximum range power and −12 dB below
the minimum range power. Typical performance for power overrange is 2 dB above the
maximum (more at lower frequencies and less at higher frequencies) and typical under
range is 12 dB. An under-range condition may cause a phase lock lost message to be
displayed.
When a calibration is active, the power range selection is switched from auto to manual
mode, and PRm appears on the display. This feature is necessary to maintain accuracy once
a measurement calibration is activated.
PWR RANGE AUTO
PORT POWER
PWR RANGE MAN
POWER RANGES