Rotax 912 radio interference

[flyingfooty28]

hi all,

 

trying to help a friend out with a on going problem with his Pegasus weight shift with 912. The aircraft was originally fitted with microair radio which had terrible interference at high Rpm, not so bad at idle and ok with engine off. Just fitted a independent radio system to aircraft ie no power supply or aerial from aircraft but original problem exists. I an assuming there is noise interference from 912??? Does anyone know of any similar issues probs or solutions.

 

thank FF

 

 

[CrayonBox]

No probs i know of, but check all the ht connections going into the spark plug caps. You may have to release the cable ties.

 

 

[cscotthendry]

A couple of things come to mind:

 

1) Check that the correct resistor type spark plugs have been used on the engine

 

2) depending on the age of the trike, it may be possible that one or more of the spark plug leads has a break in it. A break won't stop the plug firing but will generate lots of electrical noise.

 

3) Something to try: Try using shielded wire from the ignition modules to the switches. The shield should be grounded at both ends.

 

4)Also check that there is a filter capacitor connected across the regulator and that the connections between the capacitor and the reg are sound and between the capacitor and the ground are sound.

 

5)Electrical noise can also be generated by poor grounding practices. Everything (and I mean everything) that has a ground connection should be grounded to one point and one point only. Otherwise it is possible to get ground loops with stray circulating currents which can cause noise. The best method is a bus bar with multiple screws. Connect the battery negative and all the grounds to the bus bar and THEN connect the bus bar to the frame.

 

HTH

 

 

[Head in the clouds]

...... Try using shielded wire from the ignition modules to the switches. The shield should be grounded at both ends....

Yes, and the switch body must be grounded as well. If the switch is mounted on a metal panel that is properly grounded then there's no problem but if the switch is mounted on an electrically isolated panel (vibration mounts maybe), or a plastic panel then the switch body needs its own ground wire.