Alternator noise suppression

[OkieBoyKJ5JFG]

Yes, I did a search of this site as well as YouTube and the internet at large. Now I'm more confused than before.

I recently had a new audio system and backup camera installed in my 2009 Ram 1500 pickup truck. Yesterday I was told by a very experienced ham that I have a little "alternator noise" with transmission. He described it as "a whine and a little static" not loud and not interfering with his ability to understand my signal, but definitely present. Before the new sound system, nobody ever mentioned it, which doesn't prove it wasn't there before, but I'm guessing it wasn't. Possibly it's so minor that nobody bothered to mention it before, but the timing right after the new sound system makes me suspect it's related to that. The truck's engine is a 5.7 liter hemi and as far as I know, the alternator is original. The radio is a TYT TH-9800 with power wired directly to the battery positive and negative posts and properly fused. The positive lead has a relay to kill power when the ignition is turned off, also properly fused. The antenna is a Comet SBB15 6m/2m/70cm tri-band fed by 10' of RG8x coax. I don't know how much of this matters, but I figured I'd just provide it all up front.

As I said, I've done some searches. Most of the results were about suppressing alternator noise in your audio system, which isn't a problem here. Some of them mentioned placing the suppression device as close as possible to the affected device, others recommended placing it at the alternator. Do I want a ferrite bead(s), an alternator noise suppression device, or both? Exactly where should I place the device(s)? I'm a new ham, so a lot of this is new to me. I don't want to dismantle the dash to chase down a ground loop, and if there's some easy fix, I don't want to take it back to the installer to chase it down and be without my truck for a few days. I only got my amateur license in December, so a lot of this is new to me. If the solution seems obvious to you, remember that you were once a noob too. A little education goes a long way. Thanks in advance.

 

[mmckenna]

Move the negative power wire off the battery and to a body ground location closer to the radio. I had an old Chevy that did the same thing when the - lead was connected at the battery. Moved it off to body ground and it resolved the issue.

Don't spend money on the noise suppression device yet. Those just hide the issue. That can be a good thing if every other attempt fails, but try fixing the issue first.

There's some other stuff we can try, but start there.

 

[popnokick]

If it is alternator "whine" type noise it will usually vary in pitch as the engine RPM increases / decreases. And if it is that type of noise, it's coming from the alternator... which may need replacing. BUT a filter like this (there are lots of them out there) is inexpensive to try. Goes directly inline with the 12VDC to your TH9800 -
https://www.amazon.com/Install-Bay-...sprefix=alternator+noise+,aps,345&sr=8-8&th=1

 

[EAFrizzle]

Move the negative power wire off the battery and to a body ground location closer to the radio. I had an old Chevy that did the same thing when the - lead was connected at the battery. Moved it off to body ground and it resolved the issue.

Don't spend money on the noise suppression device yet. Those just hide the issue. That can be a good thing if every other attempt fails, but try fixing the issue first.

There's some other stuff we can try, but start there.

Once upon a time, you only had to make the radio happy. These days, it certainly seems as if it's as much about making the car happy as well. Moving your ground just a couple of inches can make a big difference in performance.

@mmckenna is right; try everything before adding equipment. Moving from one bolt to the next can change everything.

 

[OkieBoyKJ5JFG]

Move the negative power wire off the battery and to a body ground location closer to the radio. I had an old Chevy that did the same thing when the - lead was connected at the battery. Moved it off to body ground and it resolved the issue.

Don't spend money on the noise suppression device yet. Those just hide the issue. That can be a good thing if every other attempt fails, but try fixing the issue first.

There's some other stuff we can try, but start there.

I did it that way because that's what the manufacturer of the radio recommended, although I've since read recommendations to do it this way. I'll give this a shot, but it will involve pulling the whole harness for the radio, so it's going to have to wait until it stops raining for a while.

 

[mmckenna]

I did it that way because that's what the manufacturer of the radio recommended, although I've since read recommendations to do it this way. I'll give this a shot, but it will involve pulling the whole harness for the radio, so it's going to have to wait until it stops raining for a while.

Is this an amateur radio?
Yeah, the ham radio manufactures show this in their manuals. I think it's a "CYA" thing to cover those installs in really old (1950's and older) cars that had positive ground systems. Also, hobbyists are not always the best at doing mobile installs, and making it simple saves them some headaches.

Any of the modern high end LMR radio install documents that I've touched will show landing the radio negative lead on a chassis ground point close to the radio. Any reputable vehicle will be able to handle at least 30 amps of accessory return current on the body metal. Ford upfitter guides specifically call that out on the Super Duty pickups.
Last time I installed a high power mobile (100 watt VHF), the radio shipped with a power cord with a short negative lead. Saves them a few bucks on wire since a longer wire isn't needed.

We just bought a bunch of Harris XL-200M's at work, and I have the installation manual sitting on my desk. It shows grounding the negative lead to chassis ground.

Also, some newer vehicles use hall effect sensors on the negative battery lead that monitors vehicle power usage. The Ford manuals specifically tell you to -NOT- land any accessory negative connections direct to the battery since it will provide an alternate return path and throw the sensor off. Not a problem on older vehicles, but good habit.

 

[AK9R]

On a 16-year-old vehicle, I'd question the health of the alternator. If you can identify the alternator as the source (pitch of the noise rising and falling with engine speed), I'd consider replacing the alternator. No, it won't be cheap and, no, they don't make 'em like they used to. If you do replace the 'nator, get a name brand one and not a cheapie.

 

[OkieBoyKJ5JFG]

Is this an amateur radio?
Yeah, the ham radio manufactures show this in their manuals. I think it's a "CYA" thing to cover those installs in really old (1950's and older) cars that had positive ground systems. Also, hobbyists are not always the best at doing mobile installs, and making it simple saves them some headaches.

Any of the modern high end LMR radio install documents that I've touched will show landing the radio negative lead on a chassis ground point close to the radio. Any reputable vehicle will be able to handle at least 30 amps of accessory return current on the body metal. Ford upfitter guides specifically call that out on the Super Duty pickups.
Last time I installed a high power mobile (100 watt VHF), the radio shipped with a power cord with a short negative lead. Saves them a few bucks on wire since a longer wire isn't needed.

We just bought a bunch of Harris XL-200M's at work, and I have the installation manual sitting on my desk. It shows grounding the negative lead to chassis ground.

Also, some newer vehicles use hall effect sensors on the negative battery lead that monitors vehicle power usage. The Ford manuals specifically tell you to -NOT- land any accessory negative connections direct to the battery since it will provide an alternate return path and throw the sensor off. Not a problem on older vehicles, but good habit.

Yes, it's an amateur radio.

I'm pretty competent with the hands-on aspects of wiring, but I don't necessarily know the technical stuff, which is why I followed the radio manufacturer's directions. Now that I know there's a better way to do it, I won't have any difficulty doing it that way. I doubt my old-but-immaculately-maintained truck has any of the fancy circuitry, but even so, it's probably better to ground to the chassis.

 

[OkieBoyKJ5JFG]

On a 16-year-old vehicle, I'd question the health of the alternator. If you can identify the alternator as the source (pitch of the noise rising and falling with engine speed), I'd consider replacing the alternator. No, it won't be cheap and, no, they don't make 'em like they used to. If you do replace the 'nator, get a name brand one and not a cheapie.

I thought of that. Every 3-4 years, I have a capable mechanic do a bumper-to-bumper inspection and fix everything that needs fixing. It's due for that this summer. I'll specifically mention the alternator and if it's even borderline, I'll have it replaced.

I never put the cheap crap on my truck. That's why it's immaculate despite its age.

(No cracks about the radio being "cheap crap". I knew it was entry-level when I bought it. I wasn't sure how much I'd get into ham radio, so I didn't spend the big bucks. It's working just fine and doing everything I want. If/when it craps out, I'll replace it with something high-end. If it doesn't crap out, then there was never a need for something else anyway. Besides, the radio isn't a permanent part of the truck.)

 

[GlobalNorth]

On a 16-year-old vehicle, I'd question the health of the alternator. If you can identify the alternator as the source (pitch of the noise rising and falling with engine speed), I'd consider replacing the alternator. No, it won't be cheap and, no, they don't make 'em like they used to. If you do replace the 'nator, get a name brand one and not a cheapie.

I would have an auto electrical shop or the dealer throughly test the alternator prior to assuming it is failing due to age. Don't do it at Auto Zone or where parts sellers have a financial interest in selling you a new to you alternator.

Sometimes, a recording of the noise made at a detached scanner or amateur radio allows you to hear any signal anomalies from the part of a third party.

 

[AK9R]

That's why it's immaculate despite its age.

Congrats on keeping a good truck good. I had a 2023 Ram 1500 Laredo as a loaner for a week. Incredible vehicle, but keeping all the modern electronic widgets working over time will be a challenge.

If the "cheap crap" radio (your words, not mine) got you into amateur radio and you recognize that there might be better stuff out there, you have the advantage on many new hams.

 

[OkieBoyKJ5JFG]

Congrats on keeping a good truck good. I had a 2023 Ram 1500 Laredo as a loaner for a week. Incredible vehicle, but keeping all the modern electronic widgets working over time will be a challenge.

If the "cheap crap" radio (your words, not mine) got you into amateur radio and you recognize that there might be better stuff out there, you have the advantage on many new hams.

I didn't mean that I think the radio is crap, but that inevitably some bozo who thinks he's Elmer but is actually Mr Magoo is going to jump in with that. As a matter of fact, I think the radio is very good. At this point in my radio experience, I wouldn't get any more out of a Yaesu than I get from the TYT, but I expect that to change over time. When I'm ready for a radio with more capabilities, I'll probably be looking at "top-tier" radios. TBH, I only mentioned the brand because I thought it might have some bearing on the problem. Sometimes you'll see, "Yeah, that's a common problem with that brand" and I wouldn't waste my time chasing some other potential cause.

I spend a lot less money keeping my truck in good condition than I would on payments for a new one. Besides, I like it. It doesn't have all the bells and whistles of the new ones, but I don't care much about that stuff anyway. The stuff I do care about (remote starter, backup camera, good audio, etc.) can all be added later -- and I did. The audio system I just bought replaced one I had installed about 10 years ago. As my favorite gunsmith Mark Novak likes to say, "Do the maintenance." It applies just as much to vehicles.

 

[mmckenna]

Yes, it's an amateur radio.

I'm pretty competent with the hands-on aspects of wiring, but I don't necessarily know the technical stuff, which is why I followed the radio manufacturer's directions. Now that I know there's a better way to do it, I won't have any difficulty doing it that way. I doubt my old-but-immaculately-maintained truck has any of the fancy circuitry, but even so, it's probably better to ground to the chassis.

OK, yeah, so the amateur radio manuals that come with the radios are the bare minimum when it comes to installation. There's a lot of room for improvements.

I agree with the others, look at the alternator also. When they fail, the AC gets out of them and starts making its way into the DC system.

The DC Line filters are an option if nothing else works. but should not be needed. They are kind of a short cut for really difficult cases, often on heavy equipment. A proper install usually negates the need for them. With your truck in good shape, I'd try moving the ground point closer to the radio and see if that fixes it.


Nothing at all wrong with the radio if it does what you need it to. With clean DC power and a proper antenna, you are lightyears ahead of most hobby installs. You'd be surprised how many use a cigarette lighter plug, some double sided tape, and a $15 Amazon magnetic mount antenna.

 

[AK9R]

The DC Line filters are an option if nothing else works. but should not be needed. They are kind of a short cut for really difficult cases...

On the topic of line filters, I've had good luck with the Kenwood KLF-2. Kenwood KLF-2 Power Line Noise Filter and RF Suppressor

 

[mmckenna]

On the topic of line filters, I've had good luck with the Kenwood KLF-2. Kenwood KLF-2 Power Line Noise Filter and RF Suppressor

Yep, that's what I purchased.

I ended up giving it to a project that relied on a solar powered site with a noisy PWM solar controller. The filter took care of the noise.

 

[Chris155]

Denso new or reman alternator is the quietest and cleanest in my experience. I have had various parts house brands cause all types of interference in vehicle on board systems.

 

[OkieBoyKJ5JFG]

Denso new or reman alternator is the quietest and cleanest in my experience. I have had various parts house brands cause all types of interference in vehicle on board systems.

I'm not going to resort to a new alternator unless this one is failing or nothing else works, but I'll keep that in mind. Hopefully, changing my grounding location will fix the problem.

 

[OkieBoyKJ5JFG]

OK, yeah, so the amateur radio manuals that come with the radios are the bare minimum when it comes to installation. There's a lot of room for improvements.

I agree with the others, look at the alternator also. When they fail, the AC gets out of them and starts making its way into the DC system.

The DC Line filters are an option if nothing else works. but should not be needed. They are kind of a short cut for really difficult cases, often on heavy equipment. A proper install usually negates the need for them. With your truck in good shape, I'd try moving the ground point closer to the radio and see if that fixes it.


Nothing at all wrong with the radio if it does what you need it to. With clean DC power and a proper antenna, you are lightyears ahead of most hobby installs. You'd be surprised how many use a cigarette lighter plug, some double sided tape, and a $15 Amazon magnetic mount antenna.

Now that I know, I'll do it differently. It's just a matter of knowing what to do. The easy place to start is to change my grounding location. I don't know why above I thought I'd have to pull the whole harness. I don't need to do that. If that doesn't work, I'll start looking for other causes.

How close does the ground point need to be to the radio? The easiest place would be to the firewall, but I can run it into the cab if necessary,

I learned a long time ago that a cigarette lighter socket is a power source of last resort. I have used it sometimes for something temporary, but now I have power run directly to T-connectors under the seats. Everything that I think I might have to remove occasionally gets the corresponding male connector.

TBH, I have a bit of OCD, and professional installers don't usually meet my standards. I only use them when it's something that involves stuff like removing the dash.

 

[mmckenna]

How close does the ground point need to be to the radio? The easiest place would be to the firewall, but I can run it into the cab if necessary,

The last bunch of mobile installs I've done were remote head, so the RF decks were behind the seat. I would pick up a ground from a seat bolt or similar point and run that to a ground block. Negative lead would be attached to that. So, a foot or two at the most.

You could absolutely try it on the firewall and see if it makes a difference, might be all you need.

TBH, I have a bit of OCD, and professional installers don't usually meet my standards. I only use them when it's something that involves stuff like removing the dash.

Yeah, and that's why I rarely do installs at work anymore. My standards are higher than the industry, that means it takes longer and costs more, plus it's now well outside my job description. I have our vehicles sent out to an upfitter. I usually check them over when they get back. Haven't had one come back that I was 100% happy with, and a few that needed things fixed. But budgets are budgets and the world keeps turning.

On my own vehicles, I am very focused on the details. Just did my new truck about 2 months ago and ultimately took two days to complete.

 

[bharvey2]

In addition to moving the radio negative lead location from the battery to a chassis ground. It might be a good idea to clean up the connections (including grounding points) of your battery and charging system. Given the age of your truck, it's not out of the realm of possibility that those connections have gotten a bit corroded and are no longer living up to there potential. (Hey, I might have made pun)