[evlatests] the return of antenna 13

[Ken Sowinski]

It does sort of work.  Only IF A, and only if phase switching
is turned off.  The delay had changed by about 300 ns.  
Phases are not stable.  Constrained because of observing in sub 2
to 10 second integrations it seems that the phase jumps almost
every integration; sometimes there are two or three in row that
are the same.  The jumps are not 180 degrees.  Perhaps the 
antenna is not quite properly synchronized yet or a reference to
the L302 is not stable.

Amplitude is down enough to suggest a two arc-minute pointing
error unless the amplitude is being washed out by phase changes
faster than the integration time.

More can be done next week.  Rob thinks we will have two IFs then.