Since some time that I'm looking for those Inspeed instruments!
The more economical wind speed unit have some important limitations, only works with wind speeds greater than 3 mph and still is a read switch based unit, but the Vortex II, is very interesting! It uses an optical system with 8 pulses per revolution, instead of a read switch, and costs only $30 more.
VORTEX 8-Pulse High Resolution Anemometer
•Sapphire bearing and Tungsten Carbide-tipped shaft for super low friction
•Optical sensor with zero friction or contact
•Fully serviceable construction
•Aluminum mounting bracket for ease of installation
•Wire (standard lengths available)
•Optional tube mount
•Optional metal cups
The Inspeed wind vane is a really good unit! Far better than the ones used on Davis.
It represents a number of advantages over potentiometer vanes, including:
•Zero dead band. Many potentiometer wind vanes have a dead spot of several degrees. This device has no dead band.
•Near-zero friction. Since the magnet is not in contact with the Hall sensor, there is no friction from the sensor.
•Virtually infinite life. Unlike potentiometers that wear out, the magnetic Hall sensor is non-contacting and should theoretically last forever.