Kevin and I took measurements of the heater circuit noise using a spectrum analyzer. The heater was attached to it by both ends using BNC cables clipped to the ends of the heater. We used 600mV for the DAC voltage and +24V/-24V for the input. The temperature of the metal block changed from 34.1C to 34.7C as we took the measurement, which took about 13 minutes. We took an RMS average of 25 measurements in total to get the spectrum, shown in the first attachment. The setup is shown in the second attachment.

We first took a range of 0-200Hz for our measurement, but it was not accurate enough to see the dependence of the ASD and the frequency as the lower frequencies didn't have enough data points to accurately plot it. We then took 0-50Hz and got the result shown.

We also mounted the heater circuit box to the rack.