Pointing Hardware Upgrades at the VLA
-------------------------------------

I. Azimuth bearing fix: this is a major job taking men-months per
antenna. But it is needed to avoid catastrophic failure. Hopefully,
this will entail just a few antennas. More frequent oil-changes should
keep the rest in operation for a long time.

Ant
21 Fall 1989
09 fall 1994
23 fall 1996
01 fall 1997
17 Summer 2001

Planned in the future
18 Summer 2002
07 Summer 2003

II. Encoder electronics: new digital implementation should remove
most of the PN3DB problems.
Ant 24: Prototype demonstrated effective in 1999
Rest: one per week starting in spring 2002
As of May 1, 2002: 4 6 8 15 21 22 23 24
All behave very well on repeated PN3DB tests

III. Encoder hardware: replace external box, clean up internal
devices, and place on adjustable mounts for proper alignment.
This is being done each time an antenna comes into the barn
(1 per few months).
See antenna maint forms for current list.

IV Other things:

a. fix ventilation in yoke arm: Currently the hot air from the
pedestal room blows up one arm, while cold air comes down the
other. Plugging up the holes, and installing a fan to circulate air
throughout the arm would solve this.

b. optical pointing telescope: Use optical guide stars to monitor
telescope pointing. This could be useful for diagnosing problematic
antennas like 23.