Static Noise on Handheld

RoyS

RoyS

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Jun 3, 2012
1,742
Hunter 33 Steamboat Wharf, Hull, MA
Technical question here: Whenever I visit an unfamiliar marina mooring field, I call the marina on their designated channel with my handheld to ask where to tie up. At this point my diesel is idling and my sails are down. Over the last few years my handheld has a loud static sound that cannot be adjusted out. I first suspected that my handheld was defective but last time I shut down the chart plotter and the static sound vanished. It seems to make the noise when the engine is running and the helm chart plotter is on. Could there be something wrong with my alternator? Anyone else have any ideas?
 
Don S/V ILLusion

Don S/V ILLusion

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Sep 25, 2008
7,370
Alden 50 Sarasota, Florida
Could be any number of things. Have you tried another handheld or wired VHF? Radiated noise from the boat would likely be audible on every radio
 
D

dlochner

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Jan 11, 2014
12,803
Sabre 362 113 Fair Haven, NY
It could be an alternator or some other electronic device. Do you have an electric fuel pump?
If I understand you correctly, when the engine is shut off and the chart plotter is shut off the static isn't there. To narrow this down, there are 2 other conditions to check:

Chart plotter on, engine off.
Chart plotter off, engine on.


Is the static present on the fixed mount VHF with the antenna at the mast?
 
rgranger

rgranger

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Jan 19, 2010
12,553
Hobie 16 & Rhodes 22 Skeeter Charleston
transformers can do this also. For example, if I plug the USB adapter into my truck's 12 cigarette plug, the radio goes nuts and hisses. Obviously, the transformer is not shielded properly. One of your devices has bad shielding. You might have already found it with the alternator but I'd also try unplugging different devices one at a time. And you will have to actually disconnect them from the power supply to ensure the transformer is not energized. It is not enough to just turn them off. Good luck... and... this is fixable.
 
Ken Cross

Ken Cross

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Oct 24, 2010
2,405
Hunter 30 Everett, WA
The OP posted that the noise vanished when he shut down his plotter.

Assuming it worked normally at one time, check the grounds for the plotter. Digital equipment is notorious for creating radio frequency noise. The reasons for this are well understood, but can usually be cured. I'd suspect a corroded ground connection going to the plotter or a shield ground going to a GPS antenna. It's possible other equipment on your boat also have an issue. Just shut them down one at a time to verify the culprit. Based on what you said, I'd start with the plotter grounds (There may be more than one) and the problem can be anywhere along the ground line and based on the engine being part of it, include wherever grounds are bused together. You can also have a ground loop (actually a technical term) through other equipment. Electrical noise is almost always a ground issue

If the problem is the alternator, a whining noise should be present that varies with engine RPM. Then you will need to check alternator diodes.
Ken
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Most plotters come with a iron ferrite "bead" on the power cord. Most folks don't think the do anything and leave them off. They "choke" off the RF coming from the microprocessor and keep it inside the box. Basically the power cord becomes an antenna with the choke off. Since your body has some RF absorbing (attenuating) properties you can also try just grabbing the plotter power cord to see if the static changes.
Also agree with the other posters, alternators make whining noises that very with RPM.
 
RoyS

RoyS

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Jun 3, 2012
1,742
Hunter 33 Steamboat Wharf, Hull, MA
Thanks all. I will investigate further and report back. I do not think the noise is from the engine or alternator at this time. Both of those were running without creating noise as long as the plotter was off. My digital DC voltmeter at the battery does not waver. I never noticed the sound from my cabin VHF but then I seldom use it. I will investigate.
 
Brian D

Brian D

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Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
I use snap-on ferrite beads in my house on my power and USB cables from my PC to my external sound card, on both ends of the cables. These are located next to my ham radio and I hear all sorts of hash noise coming from the PC without them. Remember that your CP is a PC, and also a monitor (sometimes a worst offender), so bead every cable that exits the box.

One thing to keep in mind is you can add more beads if needed. Or, you can get larger beads and wrap the cable a few times around the bead before snapping it close. Experiment for best results. Ferrite beads are not that expensive. I have two boxes of them in various sizes.
 
Ken Cross

Ken Cross

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Oct 24, 2010
2,405
Hunter 30 Everett, WA
Brian D said:
I use snap-on ferrite beads in my house on my power and USB cables from my PC to my external sound card, on both ends of the cables. These are located next to my ham radio and I hear all sorts of hash noise coming from the PC without them. Remember that your CP is a PC, and also a monitor (sometimes a worst offender), so bead every cable that exits the box.

One thing to keep in mind is you can add more beads if needed. Or, you can get larger beads and wrap the cable a few times around the bead before snapping it close. Experiment for best results. Ferrite beads are not that expensive. I have two boxes of them in various sizes.
Click to expand
Ferrite beads and rings can be a big help, but I'd first look for the root cause.

Ken
 
Brian D

Brian D

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Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
Ken, I think he found the cause. The root probably being a bad ground or possibly, the dreaded ground loop. He needs to turn off the device and disconnect all cables to that device. Then turn it back on and connect one cable at a time. I am sure he will find the offensive connection.
 
SirMichael

SirMichael

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Jun 1, 2016
162
Hunter 28.5 Lake City, MN
One of my other hobbies is amateur radio, and I'm always chasing down some sort of noise in the system. The ideas of the ferret beads is a really good one. A missing ground is also very likely.

I found that on my boat however one of the cheap 12 V USB chargers caused a great deal of noise in my system. I added 25 v, 10000 µF capacitor into the DC system as a filter which took care of most of the noise when that USB charger was used.

Mike
 
rgranger

rgranger

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Jan 19, 2010
12,553
Hobie 16 & Rhodes 22 Skeeter Charleston
SirMichael said:
....

I found that on my boat however one of the cheap 12 V USB chargers caused a great deal of noise in my system. ,,,
Mike
Click to expand
Yep... I have one in my truck that causes the radio to go nuts.
 
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