Service manual

8510XF Network Analyzer Systems 3-31
Operation
RF Power
If {RF LEVEL / INTERNAL} is selected, the RF source (83651B) performs its own
leveling, using an internal detector.
• To use the {RF LEVEL / INTERNAL} mode, you must break the connection
between the ALC output of the millimeter-wave controller and the ALC
input of the RF source.
• To return to normal operation, you must restore that connection.
If
{RF LEVEL / EXTERNAL} is selected, the RF source performs its own leveling,
using an external detector.
If
{RF LEVEL / LEVELING OFF} is selected, the RF source is set to the unleveled
mode.
RF Power Settings The {RF POWER SETTINGS} softkey calls up a submenu (see “RF Power
Settings” on page 3-33).
RF Power On/Off The softkeys {RF POWER /ON} and {RF POWER /OFF} activate and deactivate RF
source power.
Unleveled/Overmod
Detection
On the second page of the menu (called up by the {MORE} softkey), the first
four softkeys determine how the network analyzer processes error
information while it is sweeping. This has an impact on sweep speed.
Explanation
In frequency sweeping, an RF blanking interval occurs at each frequency
change (see “Blanking circuit” on page 5-17). To the RF source, this
blanking interval looks like an error condition (“unleveled” or “overmod”).
To prevent the RF source from generating a spurious error message every
time the frequency changes, SRQ triggering for these errors is disabled at the
RF source throughout the sweep.
Triggering of “overmod” errors remains disabled throughout the sweep
(detection of this type of error is incompatible with 8510XF sweep
operation). However, the network analyzer is able to poll the source after
each blanking interval, and determine the status of the “unleveled” condition
flag (this verifies that no actual unleveled error occurred).
This polling process adds from 3 to 6 milliseconds of delay for each
frequency point. Some users will want to limit the amount of error polling
done by the analyzer, in order to speed up the sweep.