Rpm (Revolutions Per Minute) - Garmin G3X Installation Manual

14.3.5 RPM (Revolutions Per Minute)

UMA 1A3C-2 - Standard mechanical tach drive sensor (0 – 5 volt square wave, 2 pulses per crankshaft rev)
UMA N/T1A9-X, JPI 4208XX - Magnetic pickup tach sensor (installed on mag bleed port)
Electronic Ignition - Tach signal output at 1, 2, 3, or 4 pulses per revolution.
Jabiru Alternator - Direct connection to alternator output (6 pulses per revolution)
Rotax Trigger Coil RPM Sensor - This RPM sensor is applicable to Rotax engines. Refer to Rotax
Installation Instructions for complete installation details.
NOTE
Aircraft with dual electronic ignition systems can connect the tachometer signal output
from the second ignition to the GEA 24/GSU 73 RPM2 input (see
displayed on the RPM gauge will be the higher of the two RPM signals.
NOTE
Electronic ignition systems with open-collector tachometer signal outputs may require a
pull-up resistor between the tachometer signal output and +5VDC or +12VDC.
14.3.5.1 Lycoming and Continental Engine Sensor Installation
General Installation Guidance
Electronic Ignition - Refer to vendor documentation for proper installation.
UMA 1A3C-2
1. Remove the cap from the tachometer drive output (Figure 14-12) from the back of the engine.
2. Insert adapter tang into slotted keyway in sensor drive port.
3. Screw tach sensor onto threaded driver port, ensuring that the adapter tang on the sensor aligns
with the slotted keyway in the drive port (Figure 14-13).
4. Connect the supplied connector to the appropriate inputs on the GEA 24/GSU 73 as referenced in
the G3X interconnects in
location in the engine compartment to provide strain relief.
NOTE
The body of the sensor unit can be offset slightly to eliminate potential interference with
other engine accessories. If the interference cannot be alleviated by offsetting the sensor
directly, the builder may either install a magnetic pickup sensor or use a short tachometer
drive extension cable to remote mount the sending unit to the engine mount (or other
suitable location).
190-01115-01
Rev. L
Appendix F. Secure the connector and wire assembly to an appropriate
G3X Installation Manual - Engine/Airframe Sensor Installation
Figure F-2.1). The value
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