instabilities jun13

july,13

25jun13: Wiggle cables at polA,B at dewar and postamps
02jul13: swap cables at Dewar output
02jul13: PolA instabilitiy, hires time domain data, bias monitoring.
05jul13: drive xband amps with cbh bias box. hires data.

Summary:


Intro

     project a2675 has  reported instabilities in the xband receiver. Test were done on 25jun13 and 02jul13 to find out what was causing the problem.


25jun13: wiggle polA,B cables at dewar,postamps

On 25jun13 we did some tests looking for the instabilities. The tests were:
The setup was:
The total power was computed over the 25 Mhz band for each 1 second sample and then divided by the median value (to make the units Tsys).

The plots show the total power vs time (.ps) (.pdf):

Summary 25jun13:


    processing: x101/130625/xbtest.pro

02jul13: swap cables at output of dewar

    On 02jul13 we swapped the polA, B outputs from the dewar to see how the instabilities changed.
The diagram below shows the arrangement for the straight through and cable reversed tests:

cable setup for
        testsfile:///home/phil/public_html


    The datataking setup was:
The plots show total power vs time for the 2 tests (.ps) (.pdf)

Processing:x101/130702/xbtest.pro


02jul13 PolA instability, high time resolution data, bias monitoring

    The rf cables were returned to their normal positions. I then took some high time resolution data with the mock spectrometer. The setup was:

    The total power was computed over the 172 Mhz spectra for each 1 millisecond sample.
The plots show the total power time series and spectra (.ps) (.pdf):
The bias currents and voltages are monitored every 30 seconds. Data for 5 and 30 day stretches are shown below.
processing: x101/130702/xbmock.pro

05jul13: drive xband dewar with cbh bias box.

    The bias box from cband hi (cbh) was used to drive the xband amps. Data was then taken in high time resolution mode. The setup was:
    The total power was computed by averaging the spectra at each millisecond and then dividing by the median value over the 60 seconds.

The plots show the total power time series and spectra (.ps) (.pdf):
    Changing to the cband high bias box caused the jumps in polA to go away.
processing: x101/130705/xbmock.pro

Summary:

 

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