I have previously asked Raymarine about Relating Vane RPM to Speed on an ST60 Wind Instrument, they told me this was "proprietary information". I have now done some tests. First of all, I need to clarify something about the signals the ST60 Wind produces. The standard Raymarine ST60 Wind test procedure says:
Red to shield should read 8 volts DC steady. This is the masthead power supply, coming from the ST50/ST60 display head. If the head is damaged, you may need to provide this power from another source to test the masthead.
Blue to Shield should read anywhere between 2 and 6 volts DC. This is the port side directional element. The voltage changes as the vane turns.
Green to Shield should read anywhere between 2 and 6 volts DC. This is the starboard side directional element.
Yellow to shield should read between 0 and 5 volts DC. This is the wind speed circuit. The faster the wind is blowing, the higher the voltage will read.
Calling the Blue and Green signals "port" and "starboard" is misleading. They are the sine and cosine waves produced by the transducer. In other words, if you spin the wind direction vane you get two sine-wave signals, 90° apart.
The Yellow wind speed circuit does not produce a varying voltage, it produces a square wave, at a frequency of twice the shaft rotation speed. Some voltmeters may register this as a changing voltage, but again this is misleading. Rotating the shaft at 600RPM (10 per second) produces a 7V square wave at 20Hz, and on an ST60 Wind with factory defaults this displays a wind speed of 20kn.
Further informationIf the above tests are OK and an ST60 Wind Instrument is displaying dashes [- -] instead of speed, see
Faulty ST60 Wind Instrument from Post #19.
