[evlatests] Test summary

[Walter Brisken]

Last night between 23:30 and 0:20 LST I ran a test to search for spinning 
phases at different frequencies within X-band, thinking that possibly the 
polarity of the synthesizers in the L302 was related to the occurance of 
phase spins.  I observed two sources (0137+331 and 0017+815) each at 10 
different frequencies with the VLA and ants 14, 16.  All observations were 
6.25 MHz BW continuum with 0.4 second dumps.

The good news:

1.	No phase spins were seen (all 4 polarity combinations were tested)

2.	No 0.25, 0.5, or 0.75 strenth amplitudes were seen

3.	All IFs of antenna 14 behaved properly (except for a period during 
and following a critical power outage).

4.	All IFs of antenna 16 worked properly most of the time...

But :

1.	On the scan between 04 23 30 and 04 28 30 IFs A, C on antenna 16 
behaved oddly.  All other IFs were fine.  What was seen was jumps in phase 
at 10 second intervals (that look to be on IAT 10s boundaries).  The 
magnitudes of the phase jumps is zero at 02 26 00 and it increases 
linearly with time going both backwards and forwards in time.  Phases are 
stable/constant between phase jumps.  This time range did not include 
zero or maximal fringe rates.  (freqid=2)

2.	All IFs on ant 16 on the following scan (04 28 30 though 04 33 30)
showed the same slow linear phase ramp of ~120 degrees over the 5 minute 
scan.  The following scan was normal.  (freqid=3)

I've posted plots for these two cases on my door for the interested to 
peruse.  Nothing else stood out as extraordinary.  Tonight I plan step 
across K-band at 0.5 MHz intervals with 1 minute scans for about 2.5 
hours -- fishing for more interesting cases.  Suggestions are welcome.

-Walter