Agilent Technologies PSA Series Service Manual page 189

Hardware Options
Overview and Verification of Option 123, Microwave and Millimeter Preselector Bypass
The 3rd converter board in the instrument contains a splitter that is
used route the 321.4 MHz IF signal to the normal digital IF and also,
out the 321.4 MHz IF Out connector on the instrument's rear panel. If
Option 122 (80 MHz Bandwidth Digitizer) is installed, the second path
from the splitter is first routed to the Option 122 Analog IF board
where a switch is used to route the IF signal through the Option 122
Analog IF or to the rear panel 321.4 MHz IF Out. In order to obtain a
clean signal on the 321.4 MHz IF Out port, the 3rd converter calibrator
switch (Sw3 in figure 1) must be thrown into its down position. If Sw3 is
in its up position, the 321.4 MHz IF is still present on the rear panel but
it is corrupted by frequency response ripples caused by the analyzer
through path circuits. Option 123 provides the ability to control the
321.4 MHz IF routing so that a clean signal can be obtained out the
rear panel, although no signal will be present on the analyzer's display.
To manually control this routing, press the Input/Output key and use
the 321.4 MHz IF Out Opt softkey to switch between the rear panel
Dnconverter WBIF or the spectrum analyzer (SA) signal path. The rear
panel 321.4 MHz IF Out path is called Dnconverter WBIF because it is
usually used when using the instrument as a down converter where
wide BW is required.
Chapter 8 189