G'day.I use a Peltor FM120 Rally Intercom.
I also use an AEE ActionCam SD21.
http://en.aee.com/Action/Inform.aspx?id=10000046 Search SD21 Outdoor version.
The AEE Action Camera has 2.5mm jack for recording with an electret external microphone, so the AEE tech support advised.
I have tried RCA aux out on the Peltor to 2.5mm stereo jack but have had no success.
Is the RCA Aux output too high a voltage?