Differences between IceFree II and IceFree3 sensors

All IceFree3 sensors (anemometers and vanes) have improved heaters that are capable of ice free operation in even more extreme environments such as higher altitude locations that are near large bodies of water. The new heaters do not require any additional power and operate at the same voltage as the IceFree II sensors. The IceFree3 anemometer also has a new transfer function due to a new head design. The new heads are much like the old ones but are produced with an improved manufacturing process.

IceFree II transfer function:

m/s = (Hz x 0.547) + 0.8
[miles per hour = (Hz x 1.223) + 1.8]

NRG produced the last of the IceFree II sensors on April 29 2004.

IceFree3 transfer function:

m/s = (Hz x 0.572) + 1.00
[miles per hour = (Hz x 1.28) + 2.24]

Please note that the signal output type, mounting and overall dimensions are the same.