genny causing noise in vhf and stereo

Xplicitlnck

Xplicitlnck

Well-Known Member
Jan 2, 2012
4,030
Long island ny
Boat Info
330ec
Engines
Twin 7.4 straight drive
I've never really ran my generator while underway till I had the baby on board. Since I started using it I was told I had alot of "noise" by somebody listening on the other end of the vhf. I then noticed the noise in the cabin speakers. Shut the genny down and the noise went away, and vhf was crystal clear. How do I fix this? We're do I start?
 
X,

I have a similar situation. 12V Stereo Head Unit, 24V Stereo Amps and 24V boat. I haven't addressed it yet but I did have an email discussion with JL Audio regarding the problem. My suspicion is that there is a grounding or ground loop issue. His response was as follows:

[FONT=&amp]The noise issue you're experiencing could certainly be a groundloop issue. An easy test for this would be to unplug the signal from the headunit, and try using a source that is self powered, like a phone or iPod,playing directly into the amplifiers without the head unit. If you have nonoise, then this is most likely the case.[/FONT]
[FONT=&amp]It's generally good practice to connect power and ground for allcomponents in the audio chain at the same location. I understand it's notpossible to get the perfect scenario in applications that use two differentsupply voltages, but you should be able to cover most of the bases.[/FONT]

Not a direct solution but a place to start.
 
I well definetly try that for the stereo but hope would I do that for the vhf. Incoming signal is crystal clear it's only when I transmit out that people hear my static on there vhf.
 
X,

Use the following link as a reference to understand the concept: ( http://www.audioholics.com/home-theater-connection/ground-loops-eliminating-system-hum-and-buzz ) but this clearly wasn't written regarding a boat.

Someone with marine electrical expertise should probably jump in as to how to resolve as i'm getting in over my head. The key point is "It's generally good practice to connect power and ground for all components in the audio chain at the same location. "
 
Spark plugs & cracked wires / Ignition system and lose grounds to motor could all cause noise. Does the noise change depending on the load of the generator?Non resistor spark plugs will cause a lot of noise also.
 
Are u talking about just the generator motor or all 3 engines. I'm definetly going to go over all 3 checking for everything u described above but would the mains cause noise to? Yes the noise changes depending on rpm. What does that mean?
 
You determined that the noise stop when genny was off so I would take a close look there. Make sure your genny spark plug are resistor plugs and they are in good shape.They make noise filters also to help with this problem. Make sure your antenna connection is tight at the back of the radio. One thing you can do is run a temporary power line directly off the battery to the radio to see if this eliminates the problem.
 
Xplicitlnck said:
And I apologize I'm an electrical idiot. Please explain groundloop
Click to expand...
In a boat with 2 or more battery banks, ground looping occurs when 2 pieces in the audio path, are seeing a different voltage reference. Slight differences in the banks voltage levels, try to equalize through the signal path, and you get noise.

I would look to see where the stereo and VHF B+ are terminated. If you have external audio amps, they and the head-unit absolutely need to be have the same battery reference.

Does the gen have its own cranking battery or is it using the house or main bank?
 
Are you running your convertor/charger at the same time you're charging the batteries through the alternator?

I've been told that can cause noise, but haven't experienced it myself.
 
Wylie_Tunes said:
In a boat with 2 or more battery banks, ground looping occurs when 2 pieces in the audio path, are seeing a different voltage reference. Slight differences in the banks voltage levels, try to equalize through the signal path, and you get noise.

I would look to see where the stereo and VHF B+ are terminated. If you have external audio amps, they and the head-unit absolutely need to be have the same battery reference.

Does the gen have its own cranking battery or is it using the house or main bank?
Click to expand...
The stereo is grounded to a bus just behind the stereo. I'm assuming it's the house back but not to sure. Will Def check on that. I do have an external amp that is powered and grounded directly to the house back. And yes I have 3 separate banks one starting (charged by in board charger ) one house (charged by on-board charger) and one back for generator starting (not connected to inboard charger only to generator)
 
Jmwarren said:
Are you running your convertor/charger at the same time you're charging the batteries through the alternator?

I've been told that can cause noise, but haven't experienced it myself.
Click to expand...

I have run them both at the same time but at the time I was told I had noise in the vhf I only had the genny running with the converter charger on.
 
Ok getting closer. The noise is only coming from the 2 cabin speaker's. The cockpit speakers are wired to an amp while the 2 cabin speakers are powered by the head unit. The noise is constant while the stereo is on but seems to be mimicking the vhf signals. For example when I hit the ptt button the speakers pop a little and when somebody talks u can kinda hear the tone of the person talking if that makes sense. Now my vhf set up is as followed. 2 vhf sets one Northstar and one raymarine running off a single antenna with an electronic splitter. Both vhf radios and electronic splitter are wired to the same power feed and same ground. Any ideas?
 
should never "split" an ant connected to a radio that can save your life.
You own a 33 footer and cannot afford a dedicated ant to each radio??????????????????????????????????
That's pretty lame.
 
Bt Doctur said:
should never "split" an ant connected to a radio that can save your life.
You own a 33 footer and cannot afford a dedicated ant to each radio??????????????????????????????????
That's pretty lame.
Click to expand...

That was harsh lol. Had nothing to do with not being able to afford it. I was looking at options of trying not to have to still a new hole and mount a new antenna so I searched and asked if there was a special splitter and Shakespeare made one so that's the route I went. It was actually more expensive then going a 2 antenna setup. It was made by a reputable company so I figured it was a safe alternative. Try not to be so mean. U should have said. Well your radio is a life saving device I don't think it would be a good idea to run a splitter. :smt038
 
Harsh is finding you floating and putting you in a body bag. Being a bit harsh is a reality that few people see.
Just way too many ways to die in the boating world and not being able to call for help does not make any sense.

Here`s a poll.
How many have a "GO" bag with life jackets, flare gun w/ lots of flare shells, whistle, mirror, lanyards to loop all the people together, hand held radio in a sealed bag if they have to abandon their boat in a hurry?
 
Last edited:
research ground loop isolator. Common grounds have solved my noise issues in the past, most common , is wiring the head unit ground wire directly to the amp.
 
You must log in or register to reply here.

Forum statistics

Threads
113,186
Messages
1,428,174
Members
61,097
Latest member
Mdeluca407
Back
Top