[evlatests] L-band phase drifts

[Rick Perley]

    The L-band data, which tracks 3C147 continuously for about 6 hours 
shows remarkable phase drifts -- completely linear over the time range 
-- which are different between RCP and LCP.  Using antenna 28 (N8) as 
reference, the total phase changes over a 5.5 hour duration are about:

Antenna   RCP   LCP
----------------------------
2               -150      -410
3              1000      820
4                 -60        90
5               360        260
8                  60           0
9                420        360
15              300       210
19              430        -35
24             1550      1620
25                  0          -90
27             -200        -510
----------------------------------

All subbands appear to have about the same phase rotation. 

This is a far larger draft than was seen at 6cm.  What's happening here?