28aug14: rfi measured using lbw.

    The dl100 distomat was installed next to distomat 6 on the edge of the bowl. lband wide was then used to check for rfi while the dl100 was running.

Setup:

• dl100:
  
• positioned next to distomat 6 (az=325). It was pointed at a plate reflector on corner 12
• the power supply was in a shielded box. The distomat had no added shielding
• the dl100 was running continuously
  
• telescope:az=325,za=18
• lbw linear mode. cfr 1600 MHz
• mock spectrometer:
• 1.7 MHz bw, 8192 channels (200 Hz resolution bandwidth)
• 1 second dumps
• Experiment:
• Jorge turned the dl100 on, off while data was begin taken.

The image shows the dynamic spectra  while the dl100 was cycled on,off (.gif)

• At 57 seconds the dl100 power was turned on.
• at 162 secs it was turned off
• at 389 secs it was turned back on.
• You can see a small freq drift when the device is turned on
• the birdie below 1600 is something else.

The plots show the strength of the birdie (.ps) (.pdf):

• The top frame is polA. the bottom frame is polB
• The vertical axis is Tsys units.
  
• Black is the average spectra with the dl100 on
• red is the average spectra with the dl100 off (I've subtracted .2 Tsys for display)
• You can see the freq drift in these plots
• PolB gets to about 5.7 Tsys i a200 Hz channel.

Summary:

• A birdie at 1599.9729 is seen when the sick distomat is at distomat location 6 pointing at corner 12.
• In 200 Hz the birdie is up to 5.7 Tsys.
• This birdie was also seen in the screen room test
• We will need to shield the dl100. We can use this birdie  (in the screen room) to see how well the shielding is working
• We looked at all of lband and at 327. Not other birdies were seen on the telescope (but there was lots of rfi getting in the way)

processing: x101/140828/rfidist.pro

31jul14 distomat  in screen room

   Luis measured the emissions of the sick dl100 distomat on 31jul14 in the screen room..

The setup was:

• Agilent E4445A spectrum analyzer:
• average 20 sweeps
• 8192 points/spectra
• 6db attenuation , preamp on
• 100 MHz span, 12.5 Khz/rbw. covering 0 to 3000 MHz in 30 spectra
• 904 Efield probe with a 4 foot coax cable.
• activity
• data was taken with distomat on.
  
• data was taken with distomat off (spectrum analyzer and ethernet switch still on)\

The plots:

    The plots show the emissions from the device (.ps 6mb) (.pdf 2mb)

• The distomat on is plotted in colors
• The distomat off is over plotted in black (spectrum analyzer and ethernet switch).
  
• The first page shows plots of 0-1000 MHz, 1000-2000MHz and 2000-3000MHz
• The 2nd page shows some blowups around some of our receiver bands:
• 300-500 MHz (327,430)
• 1350-1550 MHz (lbw)
• 2000-3000 MHz (lbw)
  

Summary:

processing: x101/rfi/miscdevice/sickdl100_140731/dosickdl100.pro

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