[evlatests] ea28 L-band Polarizer

[Dan Dillon]

We have made a change and removed the RFI monitoring equipment from the 
L-band to help isolate the problem.  Can we repeat the testing to see if 
this made any difference before we just replace the receiver?

On 3/13/2022 9:07 AM, Wes Grammer wrote:
> That definitely sounds like a receiver issue, either with the OMT or 
> (more likely) the quad hybrid coupler that immediately follows it. 
> This L-band should come back to the lab for evaluation and repair.
>
> On 3/12/2022 12:40 PM, Frank Schinzel via evlatests wrote:
>> I second this observation. I have been seeing this behavior of ea28 
>> at L-band in 5 independent observations since February 26.
>>
>> On 3/12/2022 12:19 PM, Rick Perley via evlatests wrote:
>>> Something is seriously amiss with the L-band polarizer in ea28.
>>>
>>> Normal cross-polarizations are typically 5%, and never more than 
>>> 10%.  For ea28, these values are seen above 1300 MHz, but below 
>>> this, the cross-polarization rises quickly to more than 50% at 1050 
>>> MHz.
>>>
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