Scott Posted April 13 Report Share Posted April 13 My Motorola CM300D in my car always has light static background noise in my headphones as soon as it turns on. Spoke with Racing Radios on the phone and they tell me it's normal and a result of the microphone amplifier. Anyone else have this or a solution for it? On an aside I'm also getting some whine that I believe is from the alternator. Grounding directly to the battery didn't seem to solve it. Not sure what to try next. Brand new VW Alternator too. Scott Quote Link to comment Share on other sites More sharing options...
ETR Posted April 13 Report Share Posted April 13 My in-car is a motorola xpr4550 and has a little background noise that you only notice upon plugging in. After that you don't notice it anymore. Check that your antenna cable isn't running with any power, better to avoid power or grounds altogether. Also don't loop up the cable if you have extra. Where are you getting 12v for the radio? Somewhere in the car harness? If so you might also consider running 12v and ground straight to the battery with a 2 wire disconnect. That way you can also do radio check before starting the car. Quote Link to comment Share on other sites More sharing options...
turbogrill Posted April 14 Report Share Posted April 14 Are you using the digital features? That should remove a lot of the typical radio nosie, maybe it's between radio and headphones? > If so you might also consider running 12v and ground straight to the battery with a 2 wire disconnect. That is some good advice. I even think the CM300D wants you to have constant power so it remembers the last setting, that way you don't forget to turn it on between pitstops. Quote Link to comment Share on other sites More sharing options...
Scott Posted April 14 Author Report Share Posted April 14 It is set for digital mode. Again Racing Radios equipment and they said it was the mic amplifier. It's like the earphones are always "on" even when nothing is being broadcast. I do have my camera cable running along side my antenna cable. I could separate them. I'll try running independent power as well. My harness has a separate ignition on/off line so settings are kept. Quote Link to comment Share on other sites More sharing options...
TimS Posted April 14 Report Share Posted April 14 I had a lot of obvious engine hum. I removed the harness and installed it on a separate path to each device. Originally I zip tied it to a bunch of other wires. Once I did this I don’t notice the engine tracking hum. I couldn’t figure out what was causing the interference but now it’s gone. Quote Link to comment Share on other sites More sharing options...
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