[evlatests] ea17 & ea25 phase jump problem

[Claire Chandler]

Maybe, we'll keep an eye on it over the weekend.

Claire

On Fri, 1 Feb 2013, Barry Clark wrote:

> We may well have a different phenomenon here.  The thing fixed
> by a jumper has symptoms - 1 (almost always) affects only one
> baseband pair, and 2 affects the corresponding baseband pair(s)
> of the 3bit system.
>
> On 02/01/2013 11:46 AM, Jerry Langevin wrote:
>>
>> Claire,
>>
>> ea17 L302-1 installed jumper
>> ea17 L302-2 installed jumper
>> ea25 l302-1 removed a jumper
>> ea25 l302-2 installed a jumper
>> This should take care of the phase jumps on 8 bit IF's
>>
>> Jerry
>> LOIF/VLA
>>
>>
>>
>> Claire Chandler wrote:
>>> Correction, so far we have seen this at L, Ku, and Ka-bands.
>>>
>>> Claire
>>>
>>> On Fri, 1 Feb 2013, Claire Chandler wrote:
>>>
>>>> In the pipeline-calibrated datasets from this last week we have been
>>>> seeing phase jumps at scan boundaries on ea17 and ea25 in
>>>> observations that use the 8-bit system at L, Ku, and K-bands (phase
>>>> plot attached; other bands may also be affected, but we are limited
>>>> to what our observers are using in this diagnosis). 3-bit
>>>> observations do not seem to be affected. The phase jumps occur on all
>>>> 8-bit IFs (A0C0 and B0D0), and show multiple (but stable, within
>>>> scans) phase states. We are having to advise our users to flag these
>>>> two antennas completely. Is this a cable length problem?
>>>>
>>>> Claire
>>>>
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>>
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