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Mobile Line Noise

Pamm r

New Member
Apr 4, 2017
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I installed a mobile and it picks up noise from my fuel pumps I think. They are so many line filters. Which is the best in line filter to try first that may help?
 

First make sure you have a good ground to the radio and that your antenna is mounted properly. Take a short ground directly to the frame. Like a seat bolt or under the dash on a steering column bolt on the steel plate for the steering column. Anywhere that connects to the frame. If it's a magnet mounted antenna, use some ferrite chokes at the feedpoint of the antenna on the coax and also Try bonding your exhaust and body parts as well, all to frsme and make sure all your ground wires under the hood have a good connection to metal, having no paint and make sure to use NO-OX on all connections.
A filter isn't going to help much with that issue. Been there. Also you can add some ferrite chokes around the fuel pump wires.
And make sure that the engine is bonded to the frame as well as all the body panels and exhaust like i stated earlier. All of these things should help. Lastly, look into a ground loop isolator. Or what you call an in line noise filter. Get one that is rated for more than what you need. Biggest ones I've seen are like 20 amps. Most stereo shops should carry those. But I would try the other things I mentioned first, then if all else fails try one of the noise filters as I just don't think they work very well from my own experience. Hope this helps and have a good one!!
 
I have a filter on my radio, that runs in line with the power feed. That seems to have helped, some. Also, I took some advice that was suggested to me by other forum members, and I am pulling power directly from my battery. I ran my ground (negative) to a bolt on my grab bar, and my hot to the positive terminal on one of my batteries.

Back to the filter, mine is a Pyramid NS-2. I picked it up from some random truckstop that I happened to pass through. It didn't cost much.

New Egg has one:

https://m.newegg.com/products/9SIA20T2EM9088

You can probably find them, elsewhere for less, though. New Egg strikes me as over priced on everything they have.

I also see, from time to time, a Diesel branded noise filter. I have seen the same one labeled "Barjan". Those are larger, though. I have one, and have found that the much smaller Pyramid model works better.

My truck is nothing more than a massive, diesel powered, cheaply and shoddily built, rolling computer system. This thing produces a ridiculous amount of electronic noise.

I had forgotten how bad the noise was, until the other day, when I hooked up my backup radio, temporarily, in a truck that my wife needed to drive for the day. That Pyramid does work.
 
Thanks Guys, I will try those things, I have the hot and ground directly to the battery, and the whip antenna grounded to the frame, I guess that works?
 
check to see where the noise is coming in to the radio. with every thing on as normal pull the connector for the antenna out of the radio and if the noise goes away you are getting the noise in through the antenna. filters on the power cord will not help you any. grounding and chokes on the fuel pump power wires will be about the only thing that will help. try grounding 1st if the noise is coming in through the antenna.
good luck , this is a hard one to get rid of.
 
check to see where the noise is coming in to the radio. with every thing on as normal pull the connector for the antenna out of the radio and if the noise goes away you are getting the noise in through the antenna. filters on the power cord will not help you any. grounding and chokes on the fuel pump power wires will be about the only thing that will help. try grounding 1st if the noise is coming in through the antenna.
good luck , this is a hard one to get rid of.

A lot of people say this but if the noise is due to a ground loop, as it often is, and you break the loop by disconnecting the antenna have you proven anything?

She says the whip is grounded to the frame. I'm picturing a long ground wire ran from the antenna bracket to the frame. It may very well be an antenna issue. That ground wire is too long to be an effective rf ground and would be more like a radial. That radial being down near wiring for the fuel pump and other electronics may be the problem
 
more than likely the fuel tank is plastic as most car companys are doing now making them lighter. the rf will just flow right out side the fuel tank. my 2003 s10 is like that and had to run ground straps to stop it.

she just needs to know a filter on the power line will not help as the question was asked. if there is a ground loop they will know it is feeding in through the antenna.

at least I am taking it this is a female from the pic and name. have seen men do this to get free items sent to them.
 
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LOL, not wanting any free items....... My whip is grounded to the bumper, bumper to frame by way of antenna bracket. I also put a 10" ground wire from the bracket bolt to the frame. My radio is grounded to the battery...
 
have you tried unhooking the antenna to see if the noise goes away? also what radio are you running ?some times a cheap radio will be rather noisey.
if you know some one with a different radio try hooking it up and see if the noise is better. I assume you have a anl or nb switch on the radio and it is turned on.
 
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Might also try taking your ground off the battery and placing it on a frame ground instead. Like a seat bolt or under the dash on one of the steering column bolts. Also bond all body parts and the motor to frame and exhaust too. Sometimes it takes a little and sometimes a lot to get rid of noise. Depends on the vehicle and the install as well. Hope you get it resolved!! Take your time and trouble shoot one thing at a time though and it helps to write down stuff. But I would first try what Sonoma is saying and make that your first step in trouble shooting the issue. Again, hope you get it fixed and have s good day.
 
On ferrite beads/chokes; it is my understanding that you want ferrite mix 31, when working on the 11 meter band. I was unaware that ferrite was made in varying blends, depending on it's intended use, when I ordered a big ol' bag of snap on ferrite beads of various sizes. Here is a link to a writeup on the topic:

http://www.k0bg.com/beads.html

Both Sonoma and 222 bring up some good points; although I still stand by that Pyramid filter that I previously suggested. I noticed a positive difference after hooking it up. (YMMV)

What vehicle are you running your radio in? If I understand your installation correctly, you've bolted your antenna mount to your bumper. If you have a metal bumper, then that 10" wire that you have run from your antenna mount to your chassis strikes me as unnecessary. On the other hand, if you have mounted your antenna to plastic, you may wish to reconsider your antenna location.

222 mentioned taking the negative lead off the battery, and running it to a frame ground. As I previously mentioned, I ran mine to a grab bar bolt on my truck. A friend of mine, who mounted his radio on the floor of his pickup, put a ring terminal on the negative wire, and used a self tapping screw to bolt it directly to the floor.
 
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have you tried unhooking the antenna to see if the noise goes away? also what radio are you running ?some times a cheap radio will be rather noisey.
if you know some one with a different radio try hooking it up and see if the noise is better. I assume you have a anl or nb switch on the radio and it is turned on.

Thanks for the replies, I run a Corbra 29 Clissic, Truck is a Ford. I have noticed if I turn the key on with the motor off you can hear the fuel pump builds pressure for about 1 sec. that is what makes me think its the fuel pump making the noise
 

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