I am a new (to me) Rotax 912 ULS owner installed on a Titan Tornado S aircraft. At approximately 5000 and above RPM, the tach is very erratic. The tach itself is in the EFIS which is an MGL Enigma. I thought I read somewhere that installing a 220 ohm resistor from the RPM output lead to ground would stop the erratic movement of the tach. Does anyone have any recommendations on how to eliminate the erratic RPM readings?
Thanks very much.
Dennis
Yes, I checked the installation manuals that came with the a/c. Somewhere in the bowls of one of the manuals I thought I read where installing a 220 ohm resistor would eliminate the erratic RPM. Calling MGL is as useless as T.O.A.B.H. I've left messages about other issues and I have yet to get a call back.
The tach signal is a tiny AC signal so replacing the wires with 18g or 20g twisted pair helps to reduce interference from the mag leads/ generator/strobes/radios.
Also try routing the wires separate from the main wire bundle (containing the mag wires) and move the ground point away from all other grounds.
Adding a resistor does work but it will make your tach less accurate.
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