[evlatests] subreflector issues

[Ken Sowinski]

I report on the state of subreflector control.  Thhere were
two problems one of which we only became aware of during
the weekend.

1.  Until last Friday it appeared that it was still possible
for rotation and focus commands to arrive at the hardware
close enough together that one of them is ignored.

2.  For VLA antennas only negative focus positions were set
correctly, but improperly reported so that focus error alerts
were being generated.  The few antennas subject to this were
the ones that people have been complaining about over the
last few days.  Pete has now repaired this.

We think that all SW related subreflector problems are under
control and any errors attributable to the subreflector should
be taken seriously.  At the moment the rotation axis of EA16
is not behaving correctly and it looks very much like a HW
problem.  Whether it is in the FRM controller or is just a
communication dispute between the MIB and the data set is
hard to say.