Rotax 912ULS Ignition Noise
I recently bought this brand new (<30 hours) RV-12 with the 912-ULS. It has this rather weird ignition noise with incoming transmissions only. Whenever the aircraft is pointed at or flying towards a transmission source, air to air, ground to air (ASOS for instance), there is a rather loud ignition noise the sometimes drowns out the transmission. Turn the aircraft 180 degrees and the noise is gone. Transmissions received from 90 degrees seem to be OK too.
I have tested and ruled out headset issues (BOSE A20's, radio installation and coax wiring issues previously discussed. The ignition modules are properly secured, shielded and grounded. Switching between A & B ignition makes a very very slight difference when B is off. This indicates, it is ignition related. It varies with engine speed, and the directionality of this problem also indicates it has to do with the engine when it gets between the source and the antenna behind the pilot seat on the belly per plans. An alternator issue usually produces a whine rather than this static type ignition noise reminiscent of the noise we would get with aftermarket stereos in automobiles from 60's with spark plugs without resistors.
SO - Has anyone else experienced this ? Has anyone ever experienced a bad set of spark plugs or wires ?