[evlatests] ea17 & ea25 phase jump problem

[Barry Clark]

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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