The SparkSwitchPro turns out to not provide accurate RPM information from the Tach Output of a 3W Ignition. Richard is Aware that this is true and he states its a problem with 3W’s Tach output.
If you Want Accurate RPM information I have found that a gentleman on here, Rudolf , has made a small circuit that will read your Hall Sensor output and provide that to the SparkSwitchPro, and provide Accurate RPM telemetry. I have installed it with a 3W 170 Twin Spark, SparkSwitchPro and Jeti radio and it is working perfectly.
Here is a link for more information and set ups:
Although I have not tested it yet, but I am receiving another of Rudolf’s circuits with firmware to connect directly to the Jeti without the need for the SparkSwitchPro. I plan to install this in a 2nd aircraft with a 3W 106 and Jeti radio.