On-board anemometer is a Peet Bros. Anemometer.

It connects has light 4 wire telephone cable running up the mast.

Originally with an RJ11 (or RJ9?) 4pin connector, which had to be cut off to get the cable through the mast when mounting it.

Wiring pinout

GND wind speed. (pin 1)
GND wind direction (pin 2)
Wind direction signal (pin 3)
Wind speed signal (pin 4)

(Data copied from the Peet Bros. page, in case they decide to remove it.)

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