Before we were able to use the governor we have to mount a RPM sensor. We found out that the Hyperion phase sensor works very well and if you can still get one (no longer in production), we recommend to use this. But almost all other sensors from other telemetry systems or the so-called DIY-Phase-Sensor also work (google finds).
We connect the red sensor wire to one of the 3 motor phase cables. The other (3-lead) cable must be lupgged into the Servo II socket on the VBar main unit. The white lead will be the signal and must point to the orange dot. Please fix the cables close to the sensor port, to protect it from vibration damage. Use a cable strap.
If you fly a heli with a external BEC it is needed to connect the 2 battery minus leads together. If you don't do this, VBar and the sensor won't have a common reference potential voltage and the signal can not be read from the VBar.
Here is the hookup diagram for the mini VBar
Wire harness 04351 is no longer available. Please use a spare servo connector to connect the signal lead of the sensor (orange/white wire) to RX A (upper pin) and use a Y-harness to connect the power leads in parallel to an other device, or connect it to the receiver. Mind that on a Mini VBar you might need a voltage divider if your sensor outputs a signal gain higher than 5 V (e.g. r/c voltage).
Using a external power supply it can be necessary to connect the ground wires from both batteries with a cable. This depends on the ESC. If you won't have any signals or bad signals on a bench test from the RPM Sensor it is recommended to do this first.