58 Chapter 2 
Front-Panel Key Reference
AMPLITUDE Y Scale
Ref Lvl Offst Adds an offset value to the displayed reference level. Reference-level 
offsets are only entered by using the numeric keypad. Entering an 
offset does not affect the trace or the attenuation value. Reference-level 
offsets are used when gain or loss occurs between a device under test 
and the analyzer input. Thus, the signal level measured by the analyzer 
may be referred to as the level at the input of an external 
amplitude-conversion device. When an amplitude offset is entered, its 
value appears on the left side of the display under Offst (as opposed to 
frequency offsets which appear at the bottom of the display). To 
eliminate an offset, press 
Ref Lvl Offst, 0, dB. When Preset Type is set to 
Factory, pressing Preset also sets the offset to zero. See also the Ext Amp 
Gain
 key description. 
Key Access: 
AMPLITUDE Y Scale, More
Int Preamp 
On Off
Agilent ESA-E Series only (E4401B, E4402B, E4404B,  E4405B and 
E4407B) with Option 1DS. Turns the internal preamp on and off. 
Pressing 
Int Preamp (On) results in a correction being applied to 
compensate for the gain of the preamp so that amplitude readings show 
the value at the input connector. When the preamp is on, a PA 
indication appears on the left side of the display. The preamp is 
switched off in frequency bands above 3 GHz and the correction is not 
applied. In this case, the PA indication will still appear even though the 
preamp is not activated.
The preamp is specified to operate over a 1 MHz to 3 GHz range for the 
E4402B, E4404B, E4405B and E4407B. The preamp range for the 
E4401B is 100 kHz to 1.5 GHz, except for Option 1DP, which is 1 MHz 
to 1.5 GHz.
Key Access: 
AMPLITUDE Y Scale, More 
Corrections Accesses the Corrections menu keys which allow you to enable the 
corrections function and to select which set of correction factors you 
wish to modify. 
Key Access: 
AMPLITUDE Y Scale, More
Apply Corrections 
Yes No
  Pressing Apply Corrections (Yes) turns on the 
amplitude-correction factors. Corrections will only be 
applied to the sets of correction factors whose correction 
state is set to On. To turn a set of correction factors on, 
use the 
Correction On Off key in the Antenna, Cable, 
Other, or User menus. When 
Apply Corrections (Yes) is 
selected, an A will appear on the screen annotation 
whether or not a correction set has been turned on 
using the 
Correction (On) key in the Antenna, Cable, 
Other, or User menus.
Key Access: 
AMPLITUDE / Y Scale, More, Corrections