[evlatests] EVLA phase jumps.

[Rob Long]

Do we have any more information on the phase jumps?  Mark mentioned 
getting with Vivek and taking a close look.  What antenna was being used 
for a reference antenna and is it possible it had a problem?  Just 
throwing out ideas to figure out where to start.

Rob

> Vivek Dhawan wrote:
>> Went looking for time offsets, found nothing amiss. But found
>> this week's Horror Show, which is EVLA phase jumps.
>>
>> All EVLA antennas jump at the same time. No VLA antenna does.
>>
>> Jumps happen roughly 1/hour. Not every project is affected,
>> but many are.
>>
>> The phase difference between IF 1 and 2  is mostly a multiple
>> of 60 degrees, though other values are seen.
>>
>> I seem to recall something about a cable needing its length
>> adjusted when this happened. Jim, Rob or Barry might remember
>> what I'm on about? I also recall that was an antenna- specific
>> thing, this current malady affects all EVLA antennas.
>> Perhaps the L350 or something else connected to the timing is
>> jittery?
>>
>> The last good project I can find is AM979, 2009 march 10,
>> UT 06:00-13:00. after that (Wednesday) was TSTMAINT, MAINT,
>> PN3DB, APEVLA(Rick), EMTST(Emmanuel), BASEL, POINT. The last
>> 2 were definitely afflicted, and it appears to be still
>> going on now. So my guess it broke last Wednesday, that's
>> already a 120 hours of mangled data.
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