[evlatests] RFI birdie in Ka-band

[Ken Sowinski]

On Fri, 18 Aug 2023, Evangelia Tremou wrote:

> Looking at some test data taken yesterday (Ka_3bit_23A256*), the 30.976GHz 
> birdie is not present.
>
> The scripts was using:
>
> LoIfSetup(True,"33GHz",35900,37900,28500,30500,1)

This sets L301-1 to 14404 MHz, so if there were a birdie I would expect
to see it at 28808 MHz in this case.

Ken


> Lilia
>
>
> On 8/18/23 09:59, Ken Sowinski via evlatests wrote:
>>  On Thu, 17 Aug 2023, Rick Perley via evlatests wrote:
>>
>>>  I find a fairly strong 'birdie' in Ka-band -- at 30.976 GHz. This is the
>>>  242nd multiple of 128 MHz.  Don't know if this is relevant ...
>>
>>  This was in 23A-317 observed on July 17, 2023 using
>>
>>       LoIfSetup(True,"33GHz",37500,35500,33500,31500,1)
>>
>>  Which resulted in an L301-1 setting of 15498 MHz, the second harmonic
>>  of which is 30976 MHz.
>>
>>  We have previously seen such birtdies in Ka band with a variety
>>  of tunings; some of them much stronger than this one.  I don't
>>  know if anyone was able to show whether it was really the second
>>  harmonic getting into the RF, or some other path with the same
>>  outcome.
>>
>>  Ken
>>
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>