Intro:

       On 28jan13 the anritsu spectrum analyzer was used to check the rfi coming from the A/C unit atop building II.
The setup was:

• 1 Mhz RBW
• span 200-400 Mhz
• average 10 sweeps.
• preamp on
• The 3cm loop probe (902B H-field) was used.

    I walked around the unit and found the strongest rfi coming from  the control panel on the side of the unit.

The plots shows the rfi when the probe is close (inches) and then far (many feet) from the control unit display (.ps) (.pdf):

• The black line had the probe close to the control display
• the red line had the probe a few feet (say 4) from the control display.
• combs:
•  8.3 MHz comb (311.479 one freq)
  
• 31.256 Mhz comb (298.477 one freq)
  
• I didn't see a lot of rfi above around 600 Mhz.
• The building 2 power cycle showed this rfi in the telescope data.l
  

Other things to check:

• The vents feel like plastic. Check with a dvm to see if they conduct.

processing: x101/130128

rfi_page