[evlatests] Phase stability of ea27 {External}

[Paul Demorest]

Hi all,

Not sure if this is relevant but for the record:

Four antennas including ea27 have recently been showing large (20 to 30deg
peak-to-peak) phase modulation at 10 Hz: ea13, ea17, ea23, ea27.  We have seen
this kind of thing occasionally over the past few years and have found it can
be fixed by power-cycling the L305.  This was done June 7 and at the time
seemed to clear up the issue on ea13 and ea27.  However new data taken today
shows the 10 Hz has come back on these two.

I don't know if this issue is directly related to the phase jumps, however in
May, Drew reported phase jumps on three of these antennas in pipeline output
(ea13, ea23, ea27).  This is what led to looking at the high time resolution
data, and finding large 10 Hz on all of them seemed a bit suspicious.  Maybe
there is a common underlying cause for these two symptoms?

This was written up in WO-17369, 17370, 17371, 17372.

Cheers,
Paul

> Hello,
>
> Eddy Sanchez verified cabling at the L300 and L305, cables at the
> splitters and in the Utility rack. He did not see anything loose.
>
> Dave
>
> On 6/30/2023 11:48 AM, Rick Perley via evlatests wrote:
>> Some support for a ratty connector:  In looking at my gain solutions, I
>> see that ea27 often has both ratty (variable) amplitudes and phases
>> within a scan.  No other antenna does this ...
>>
>> On 6/30/23 11:44, Ken Sowinski wrote:
>>> On Fri, 30 Jun 2023, Rob Long via evlatests wrote:
>>>
>>>> If we have a loose connection between the L300 and LO or DTS
>>>> splitters, something like this could occur. Do we see this effect in
>>>> both 8-bit and 3-bit?
>>>
>>> I think Rob has the right idea.  Given the pervasiveness it must be
>>> at the head of the LO chain (L300 to L305) or the LO transmitter; or
>>> The L302(s) not being phase stable with LO offsets.
>>>
>>> Tha latter can be ruled out by running a test with the Widar offset set
>>> to zero.
>>>
>>> Ken
>>
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