097-10603-01 Rev. A – November 2004 X72 Desiger’s Reference and User’s Guide 41
Design Integration Considerations
X72 Reliability and Maintenance
X72 Reliability and Maintenance
Reliability
The X72 is designed with a goal of twenty years of operation without retuning. To
accomplish this, the major mechanisms impacting the need for maintenance were
addressed. Thus, each X72 has been designed to have excess rubidium fill in the
lamp to last for the required period, sufficient pulling range for the voltage controlled
crystal oscillator, and sufficient dynamic range of the rubidium control loop.
Maintenance
User Maintenance
The X72 is considered to be factory serviceable only. There is no user service
adjustment or maintenance required.
A monitor signal is provided to allow the user to track indications of pending
end-of-life for the unit with sufficient warning to avoid a total and sudden failure of
the unit. The key indicator of health is the service indicator that indicates when the
Rb physics package or on-board quartz oscillator are near their operating or control
limits.
If the Lock signal does not indicate a Rb lock within the specified time, or the
Service signal indicates that the unit has reached the end of its effective life, remove
the unit and return to Symmetricom for service. The Service indicator is valid only
when the Lock signal indicates that the unit is locked.
For information on how to return a unit for service, see Repairs, on page 48.