Background noise in radio headset RV-9

[expressobike]

Hello all,

Just got a bran new RV-9 and I have this background noise all the time in my headset kind of a high pitch sound. Not wen I talk but when I listen. The other person can hear it to on the other side of the communication. I tough it was the alternator and changed it. 500$ later its note the problem... Maybe a ground wire somewhere?

Can anyone help me with this issue?

Thank you
Expressobike

[DucatiMike]

I was reading some of the PDF documents I downloaded from the AeroElectric web site and came across this statement...

Another common "noise"
complaint is strong alternator whine in the headsets . . .
sometimes when radios and intercom are OFF! Both of these
phenomenon are commonly driven by what are called
ground loops.

In metal airplanes, headset and microphone jacks should be
mounted on insulating panels or insulated from metal panels
by the use of fiber shoulder washers. We supply extruded
fiber washers from our website catalog for the specific
purpose of insulating headset and microphone jacks from
local airframe ground. Microphones and headsets should
take their low-side audio connections on shields or separate
wires all the way back to where the interphone, audio
distribution amplifier and/or radios are grounded . . . usually
right behind the panel. This is one reason why I recommend
the B&C forest-of-Fast-On-tabs for grounding all instrument
panel mounted equipment. Single point grounds are, by
definition, loop-free.

Hope that helps you,
Mike

[expressobike]

Thank you for the info. I will investigate.

Sacha