MGL Avionics User Forum

Found it. details later.

UMA T1A9-2 sender, 1.5 pulses per revolution.

I am installing a IEFIS Challenger & RDAC with a Lycoming O-540. RPM indicates 10% of actual RPM (150 while at 1500RPM). I tried moving the Ballast jumper but then got no indication. Suggestions?