SICK DL100 distomat
measured using lbw.
31jul14: rfi measured in the screen room
The sick dl100 distomat is
being tested to replace the current sent of distomats used to
measure the platform height.
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.
- 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
- lbw linear mode. cfr 1600 MHz
- mock spectrometer:
- 1.7 MHz bw, 8192 channels (200 Hz resolution bandwidth)
- 1 second dumps
- Jorge turned the dl100 on, off while data was begin
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
- the birdie below 1600 is something else.
The plots show the strength of
the birdie (.ps)
- 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.
- 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)
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
- 904 Efield probe with a 4 foot coax cable.
- data was taken with distomat on.
- data was taken with distomat off (spectrum analyzer and
ethernet switch still on)\
The plots show the emissions from the device
- 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
- The 2nd page shows some blowups around some of our
- 300-500 MHz (327,430)
- 1350-1550 MHz (lbw)
- 2000-3000 MHz (lbw)
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