Fluttering Sound (Interference) in VHF Radio While Engine Running

SSTJ

SSTJ

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I could try to post a video of the sound, but it's a puttering / fluttering sound. Maybe 2-3 'clicks' per second. I only hear it while receiving a transmission while the engine is running. Cut the engine and it goes away. Also, the sound is in sync with the engine RPMs. When I give it gas and the RPMs climb, the fluttering sound increases in speed/frequency. By 2.5k or 3k RPMs, the fluttering is so quick that it almost starts to sound like white noise.

This is new; just started today. Have had the VHF installed for about two months.

Edit: It went away for three days, and now it's back. Tonight, I had a perfectly clear 10-minute conversation with someone on VHF, parked my Jeep for an hour, came back and it had started the fluttering again.
 
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WSS said:
Try something like this:

https://www.amazon.com/dp/B00XKV114K/?tag=wranglerorg-20
It is most likely tramp EMI from a unshielded or poorly shielded alternator. Does not have to be the one I linked to, but you get the idea. Most car audio shops should have them on the shelf too.
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Thanks very much. Would this diagnosis still make sense if the the problem just started yesterday, but hadn't been an issue for the past two or three months?
 
SSTJ said:
Thanks very much. Would this diagnosis still make sense if the the problem just started yesterday, but hadn't been an issue for the past two or three months?
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Yes. Something has changed. Try cleaning and tightening tour battery connections.
 
If it's a new thing you might check your spark plug wires and plugs. Sometimes you can spray plug wires at night with a water solution, mist them and you'll see the arc.
 
Ironman said:
Are you connecting directly to the battery? Do folks you are talking to hear the noise?
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Thanks. Yes, the Yaesu unit is wired directly to the battery. No, others don't hear the noise when I transmit, but I am eager to know what you'd have in mind either way.
 
Zorba said:
Sparkplug noise - the above filter took care of it on my CB. Since I afterwards wired my VHF/UHF and GMRS radios out of the same source, I've never had any issues with them - the filter runs all three.
Click to expand...

Thanks Zorba. But since this just appeared yesterday, I'm wondering how to track down what's changed. Any ideas? Spark plugs going bad or something?
 
pagrey said:
If it's a new thing you might check your spark plug wires and plugs. Sometimes you can spray plug wires at night with a water solution, mist them and you'll see the arc.
Click to expand...

Thanks. And sorry to be a dunce, but what am I checking for—just a good connection, or checking to ensure that they are firing well? As you can tell I have no strong mechanical background. The engine is running fine, if that means anything about the plugs.
 
Small cracks in the spark plug wires allow sparks to jump from the wire to any local ground. Large gaps on worn plugs make it much more likely the spark will form where it isn't supposed to. The cracks in the wires can be small enough you can't see them, that's why the water test in the dark is useful. You'll see the it light up as it arcs.
 
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I assume that you are also using two wires to the battery, positive and negative posts. One thing you can try is to use a second battery to run just the radio. This will isolate that circuit as a test. Noise can come from the plugs, wires and even the fuel injectors. The filter should resolve your issues but there also may be a simplified fix.
 
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Update: It's not happening today. Will have to wait until it happens again to test things, but in the meantime I suppose I can look for loose connections.
 
SSTJ said:
Thanks Zorba. But since this just appeared yesterday, I'm wondering how to track down what's changed. Any ideas? Spark plugs going bad or something?
Click to expand...
In short, nope - haven't a clue. "Usta-work" vs. "neva-work" are two different animals!
 
Interesting, thanks. I will check to see where my negative goes. Whatever I did, I remember asking on here first.

But, since this just started happening yesterday, and has not been a problem for the past two or three months, I suppose it wouldn't have to do with how I originally wired it, right?
 
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