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PNA 10MHz Ref Unlock Issue

Question asked by ianh on Feb 16, 2008
Latest reply on Feb 19, 2008 by dgun
Setup is as follows:  I am using an E8263B PNA.  A 10MHz local oscillator is feed into the 10MHz Ref Input.  The 10MHz Ref output is chained through two Agilent E8257D PSGs.  The instruments are being controlled automatically with LabView software.

The PSGs periodically report a Ref Unlock error during software controlled measurements.  I so far have not been able to witness when this event occurs, but it seems to, at times, interrupt my measurements.  So far, I’ve only been able to recreate the unlock error by closing the PNA application and restarting it.  On the application Initializing splash screen the Unlock shows up on the PSG for a short period of time (<100ms).  Capturing this event on an o-scope, I see a ~500Hz phase change on the PNA 10MHz Ref Output which lasts about 100ms before it locks back to my LO.  It seems as if the PNA is switching back to its internal 10MHz for a short time before it locks back in to the external 10MHz.

I am making an assumption at this point, but I think this might be same event that the LabView software is causing, though I do not know when or why it occurs.

I am thinking of switching the 10MHz order of my instruments to see if that fixes the problem (PNA last, instead of first).  However, I am still curious as to how/why an event like this may occur for future reference.  If anyone has any ideas or information on this please reply.  

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