VHF engine motor noise

[jstillw]

I know I have seen the answer to this before, however could not find it.<br /><br />New VHF fixed mount is producing a crackle feedback sound ONLY when the engine is running.<br /><br />Radio is wired to same bus as all other electronics inside the center console. All lines including my coax antenna cable runs through conduit up to the center console.<br /><br />I think alternator is causing the noise.<br /><br />Do I run the power direct from the battery or is there some type of filter I can install in the center console?

 

[vipzach]

Re: VHF engine motor noise

Alot of the time, noise is picked up in the ground wire. Try moving it first.

 

[amirm]

Re: VHF engine motor noise

Resolving noise problems can be challenging. First, remove the antenna and see if it is still there. If so, then you are sure it is induced through the power line and not the antenna.<br /><br />If it is power related, make sure the ground is solid and tied down well. Second thing would be to get a noise filter from radio shack or car stereo shops. <br /><br />If the above does not work, run the power cable temporarily away from the other cables (outside of the conduit) to see if the noise is induced "capacitively". In other words, the noise is being picked up by the location of the wire and not through the powerline itself.<br /><br />Note that reducing the noise at the source is much more effective than filtering it after the fact. So you may want to make sure your alternator is running well. BTW, make sure the alternator is the cause by rev'ing the engine. If the pitch does not increase, the it is not the alternator.<br /><br />Anyway, hopefully you get some ideas out of this. Dealing with noise like this can be quite difficult at times. Ultimately, you may need to replace your alternator or the radio to resolve this.<br /><br />Amir

 

[18rabbit]

Re: VHF engine motor noise

Your problem is not uncommon. Both Amir and Vipzach have some good ideas on finding/fixing the problem. Without changing your boat’s wiring, there are two ways to get rid of alternator ‘noise’ in your electrical system; one is to filter the output from the alternator (70kHz – 100mHz), preferred because it cleans up the whole system. The other way is to filter the +/- lines at the radio (audio – 200mHz).<br /><br />Considering all of the electronics toys we have on boats today, I am a proponent of filtering the alternator, at the alternator. Usually the filter goes within inches of the alt’s output. Something like Newmar’s 150A alternator filter will handle alternators up to 150amps. I have a couple of these, on one each alternator, to keep the whole system clean. MSRP: $155, but about $110-$120 street price. <br /><br />If you decide to filter at the radio, something like Newmar’s PC-10 will condition both the [+] and [-] lines for the radio. The filter is rated for 15amps intermittent (5-min) or 10amps continuous duty. The PC-25 is a 30/25amp version. The filter should be installed within a couple feet of the radio. MSRP: $64, street price is a few buck less.<br /><br />Worse case scenario is you need both filters, but then you knew owning a boat wasn’t going to be cheap. I do not have/need any of the PC filters, I just filter the alt's output and all is well.<br /><br />On Newmar’s homepage there is a yellow button for [Steals And Deals] where discontinued products are sold. There are a few PS-5 5amp filters left for $5/ea. I am not familiar with the PS series, but I suspect it is an inline filter/capacitor. A typical 25w VHF is pulling about 5amps of 12vdc, max. It’s possible this inexpensive filter will solve your problems, but you should call Newmar and talk to them about it. Also check the spec section of your radio's manual to see the max power used. If you do call Newmar, you might ask about smaller versions of the 150A alternator filter. I know they used to make a 80-amp version but it is not listed in Newmar’s current catalog, but you can still find them sold on-line. Note the picture of 4 diff filters here, including the 80A alt filter:<br /><br /> http://www.newmarpower.com/noisefilters/noisefilter.html <br /><br />Good luck!<br />

 

[briannh1234]

Re: VHF engine motor noise

Cheap thing to try is to run the power and ground directly to the battery. The battery acts like a big filter.

 

[AndyL]

Re: VHF engine motor noise

You could also try using resistor spark plugs. I changed mine from standard to "R" type and VHF was cured. Of course if the noise is coming from your alternator this won't effect a cure.

 

[BrettNC]

Re: VHF engine motor noise

This sounds like ignition noise. Ignition noise makes a crackle, whereas an alternator produces a higher frequency "whine".

 

[jstillw]

Re: VHF engine motor noise

Thanks for all the thoughts....... It is a crackle and not a high pitched noise. No change when the engine is rev'd.<br /><br />How do you remove ignition noise???

 

[amirm]

Re: VHF engine motor noise

Did you remove the antenna to see if it goes away?<br /><br />Amir

 

[Boatist]

Re: VHF engine motor noise

Interesting problem, both ingition noise and alternator whine should change as the motor RPM change. <br /><br />What type motor is on the boat, is it an outboard without a voltage regulator or an I/O. Could be voltage to high for your radio.<br /><br />Do you have a depth finder that turns on when you start your motor.<br /><br />Does your blower turn on when you start your motor.<br /><br />Crackle or frying sound often just a loose or dirty battery connection or any loose power conection.<br /><br />Finding the source of the noise is the key to fixing it without spending a ton of money.<br /><br />I would start by turning the radio on and open up the squelch so you can here static.<br />Is the noise present at this time. If not then turn on one at a time the depthfinder, blower, bildge pump. Make sure the battery connection is clean and tight, also alternator connections. <br /><br />Then turn on the ingition with out starting the motor. Note your voltage before starting the motor. Finally start the motor and again check your voltage. If it only makes noise with the motor running and does not change as you rev the engine I feel must be a voltage regulator, or a loose connection and viberation. I would check the battery connection closely.

 

[jstillw]

Re: VHF engine motor noise

trying to get back on the boat to test.... may take awhile.<br /><br />thanks