[evlatests] More Missing Scans

[Rick Perley]

    The first 'receiver rotation' observation (pre-rotation) was made 
yesterday evening.  There are 12 different tunings involved, each 
including a strong source (3C147 to measure cross-polarization) and 
nearby noise field (to measure sensitivity).  The order of observing was:

    L -> XLo -> XHi -> CLo -> CHi -> S

    with this cycle repeated twice. 

Each runing, except L-band, is an 'extended OSRO' style mode with 1 GHz 
bandwidth, and the two IF pairs split to cover adjacent 1 GHz 'chunks'.  
At L-band, the subbandwidths are reduced to 64 MHz, so the two IF pairs 
cover the lower and upper halves of the 1 GHz bandwidth. 

    I should have gotten two observations (each with two sources) at 
each tuning.    But for both X-band tunings, I got only one.  The first 
time around resulted in no data in the archive.  Fortunately, for this 
experiment, the second cycle did provide data. 

    The conversion from L to X involves a correlator reconfiguration, 
right?  Are we seeing this old problem again, or is something else 
happening?