[evlatests] slow attenuator setting on ea16 IF D

[Rick Perley]

More evidence to help theorists...

On the rapid-band-change experiment run last evening, antenna 16, IF 
'D', had two very different fringe amplitude values -- the first, which 
lasted the entire length of the scan, was 6 minutes long.  The second 
level, which was in place for the entire rest of the run, was about 2dB 
lower.    *** This was at L-band***. 

    It seems to me that the command to set the attenuator in 16D didn't 
get executed until long after the others had been received. 

    More information shortly, as I work through the data.

    Rick

Eric Chavez wrote:
> I have another theory, if this was a Ka converted path script there is a 
> common failure with the switches on the U/X LCP/RCP RF plates S1, and 
> S2. These switches have had similar symptoms prior to failure.
>
> This could affect only IF-D.
>
> Was this a Ka converted path script?
>
> Eric
>
> Claire Chandler wrote:
>   
>> Why would this only affect IF D, and not A/B/C?
>>
>> Claire
>>
>> On Mon, 8 Aug 2011, Doug Whiton wrote:
>>
>>     
>>>> I would consider a sticky subreflector that moves a little further
>>>> each time it is commanded until it finally gets there.
>>>>
>>>>         
>>> I witnessed this just last Friday.  I noticed that Ants. 11, 12, 13, 16
>>> and 27 were having difficulty settling into position.  They would move to
>>> within a few counts on either side of the intended position, waiting about
>>> 15-20 seconds between each try, then overshoot to the other side.  I
>>> talked with Wayne about this.  He said that a firmware change and possibly
>>> a hardware change would be necessary if we wanted to fix this.
>>>
>>> Doug
>>>
>>>
>>>
>>>
>>>       
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>
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