Correct RPM measurement


I have previously asked about the unstable appearance of RPM sensors.
I heard about the bad sensor and I ordered a new sensor.
Futaba RPM sensor … very expensive
But I bought.

There was one problem here.
RPM is doubled.
In fact, I doubt it is true.
Anyway, the problem is that I can not measure the RPM of my engine helicopter accurately.

There are three questions.

  1. The governor is in use.
    If the governor does not get the correct RPM value, does the RPM of the helicopter become unstable?

  2. Why does my engine’s RPM seem to double?
    I have a good sensor.
    Very firmly fixed.

  3. I set the RPM to 6000 as the governor.
    Gear ratio 5.1, speed 1180
    5.1 x 1180 = 6018
    However, my helicopter has a RPM of 5500 and it can not keep it well.

Always a big help.
Overwhelming appreciation