User's Manual

AT7120 Owner Manual Rev. 1.1 – March 2009 65/76
The power value displayed on this screen is a value fed directly from the output of the reflectometer and
is the same value that is provided to the ALC s (Automatic Level Control) system circuit. The system
allows for a certain flexibility of adjustment by providing at the same time the power level display in
order to verify the actual power level. It is not recommended to adjust for very low values of ALC
voltage as this may cause the power to become unstable.
For higher ALC values (above 1.3V), the power will change with the variation of the ALC voltage. In
case this simultaneous variation does not occur, it is likely that there is a fault in either or both, the Up
Converter or final RF amplifier. This type of occurrence should be reported to the Linear Industries Inc.
In this screen, the ALC is disabled for precision adjustments of the power level and to have full manual
control of power, use the ENTER and UP and DOWN keys. In any another environment or screen, the
ALC system returns to an enabled mode in order to control the power level.
WARNING: It is important not to set the programmed values of the ALC and consequently the final
RF power level above the nominal value of the equipment: This may cause damage to the internal
modules and may void the warranty on the unit.
4.3 ALARMS MENU
This transmission equipment has a system of alarms. These are illustrated by symbols at the right side of
the display screen: * and #. The signal * represents the occurrence of a current alarm. The signal #
represents an old alarm, i.e. an alarm that has already occurred and has been cleared. Under normal
operating conditions neither of these two symbols will be displayed on the screen.
When the * is displayed, the current alarm screen should be accessed to verify which alarm is occurring.
4.3.1 CURRENT MENU
This menu displays the current alarm messages i.e. alarms that are still present and have not yet been
cleared.
The current alarm messages are updated when entering the CURRENT MENU.
To update the list, you must leave the menu screen and then return to the ALARMS using the ESC
option. Then access the CURRENT menu option again.
Option NXT shows the next alarm message. If there are no alarm messages it will read as follows:
< ALARMS LIST START! >
< ALARMS LIST END! >
Option ESC returns to the previous screen.
The following messages may appear on the current alarms list: