[evlatests] Antenna 24

[Ken Sowinski]

On Tue, 12 Feb 2008, Jim Jackson wrote:

> Isn't it possible for observations to take the antenna over the
> top?  I seem to remember Ken or Rick running some test observations
> some time back that did this. Can it happen in normal observing?
>
> If the vacuum pumps can start automatically and the antenna can go
> over the top automatically, we have a problem.

Pointing and baseline runs use over-the-top observations to
separate effects which otherwise would be strongly correlated.
I don't rememeber being made aware of any problem related to
the cryo system and observing over the top.  If the vacuum pump
can start automatically and antenna happens to be over the top
at the top what happens?  What has changed to require this
restriction?

We have pointing and baselines runs scheduled for Friday night
to measure parameters for all the moved antennas.  Need a request
be made now to allow it to happen?


> At 03:46 PM 2/12/2008, Rudy Latasa wrote:
>> Cryo found a problem on antenna 24 today which was created by
>> someone taking the antenna over the top while one of our vacuum
>> pumps was running. Taking the antenna over the top while the vacuum
>> pump is running will cause the pump to blow oil out the exhaust and
>> all over the vertex room and on top of the racks.
>> If anyone has a need to take the antenna over the top, please check
>> to see if either of the vacuum pumps are running, either by a visual
>> check of the pumps or by checking the rcvr screens and looking at
>> the VP voltages. The pump voltage when the pump is off should be
>> around 9.9 volts, if the VP is below 9 volts then it is not safe to
>> run the antenna over the top. If it's critical to take the antenna
>> over the top contact cryo and we will turn the pumps off. Thanks Rudy
>
>
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