Amateur radio interference: 2010 Honda Accord

[style26062]

Moderator: The following post was moved from this thread since that thread was about a year old.

Wondering if you ever found a solution for this? My 2010 Accord has the same issue.

 

[FeedForward]

Can't figure out from the original posts if the interference only happened with the engine off. This is not so mysterious, but don't look for a standard solution to any RFI problem. If the radio itself is causing interference, it might be from the FM section's local oscillator leaking backwards out the antenna, or out the power plug, or out the speaker connector. Why else would a radio be radiating 140 MHz?

It can take multiple routes. Pulling connectors one at a time can help you to diagnose. Don't be amazed that the interference changes or goes away under certain conditions. Every time you alter the car's electrical system by starting the engine, stepping on the brakes, turning the headlights on, etc, you are switching in a different part of the overall electrical harness, which might make the interference worse or better. I'd stick with the radio on this one until you prove otherwise. I doubt if the cars EMU is operating anywhere near 140 MHz.

FF

 

[style26062]

The RFI starts when the key is turned to the ON position whether the engine is running or not. It's present with the stereo on or off as well.
It ends about 10 seconds after turning the key to the off position. (Guessing it takes that long to drain the caps in the stereo.) I haven't done any further testing, but based on the original post it definitely sounds like it's coming from the stereo circuit, and that it's common to Honda's. My vehicle has the in dash 5 disc changer, just in case others want to see if they hear a carrier on 147.76.

When I have time I'll see if I can determine where it's radiating from with an HT or SDR. The SDR should help figure out if it's a harmonic emission. I'm also curious how far away from the vehicle it can be heard. It would make sense if it were radiating from the stereo antenna, which is pretty close to my trunk mounted VHF/UHF antenna.