[evlatests] Tardy Antennas

[jjackson]

Antennas 14 and 21 are actually running at exactly the speeds originally 
specified by NRAO & E-Systems when the antennas were built. Apparently, 
servo went through and upped the Azimuth speed on all of the antennas 
several years back. This fact was missed/forgotten when we did the new 
ACU design.  When we realized it, we attempted to speed them up but 
introduced a fairly severe stability problem. Since it was the last day 
of Greg's visit and the antennas needed to be returned to operations, we 
simply slowed them back down to spec and have that on the list for 
Greg's next visit.

Servo will have to explain the other three antennas.

Cheers,
Jim

Jim Jackson
Project/Lead Hardware Engineer
Very Large Array(VLA) / Very Long Baseline Array(VLBA) radio telescopes
National Radio Astronomy Observatory
1003 Lopezville Rd.
P.O. Box O
Socorro, NM 87801
(575) 835-7132 (W)
(575) 835-0158 (H)
jjackson at aoc.nrao.edu

On 8/15/2014 9:20 AM, Rick Perley wrote:
>      We ran a test last night which required some long slews.  It turned
> out that some were long in azimuth but not in elevation, and vice
> versa.  Looking at the data, it's clear that:
>
>      1) antennas 3, 5, 12, 14 and 21 are slower in azimuth slews than
> the others.  Antennas 14 and 21 are the worst -- fully 20 seconds behind
> the fastest ones for changes in azimuth of about 120 degrees (3 minute
> slew).
>
>      2) All antennas are very close in elevation slew speed.
>
>
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