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Ignition noise from K40 antenna

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mdouble

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I recently purchased a Midland 75-822 with I installed in my Suzuki Grand Vitara using the vehicle adaptor kit. It is attached to an external K40 Antenna with a 58" steel whip. The antenna is roof mounted using the magnet mount base. The coax is the standard cable supplied with the antenna.

On my first use, I discovered the radio is picking up lots of ignition noise. Initially, I suspected this noise was coming from the DC power supply. However, after reading an article related to this problem, I performed a simple test as recommended to determine the source of the noise. The test advised unplugging the antenna cable. If the noise continued with the antenna disconnected the source would be the power supply. The article advised that in that situation the noise could be eliminated by installing a filter on the power cable at the source.

My test showed the source of the ignition noise to be the antenna and not the power supply. I am curious to know if anyone else has had this problem, and more specifically found a solution?
 

mmckenna

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I think any of us that have been around for a while have battled this at some point.

Couple of questions…

Where is the mag mount located on the vehicle, exactly?
- Have you tried moving it around to different locations?

Where, exactly, are you getting your power from?
- Are you tapping into any existing wiring, cigarette lighter plugs, accessory connections, etc?
- Where is the negative lead connected?

How is your coaxial cable routed? Is it running along side any other wiring?

Can you describe the noise you get when the antenna is connected?
- Is it a whine?
- Does the pitch of the whine change with engine speed?
- Is it a constant static?

Before purchasing power line filters, there's some things you can do.
Power should be pulled off the battery. Tapping into existing vehicle wiring, including, but not limited to, the cigarette lighter can be a big source of noise.
Using a short ground wire from the radio chassis directly to the vehicle body can solve some issues. Relying on a long negative power wire or the antenna coax for a good ground can be problematic.
 

prcguy

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Good suggestions so far. The antenna would not be the source of the noise, its just picking up whatever is already radiated into the air.

Another thing you can try if you suspect the noise is coming in through the antenna and not the power leads is walk around the vehicle when its running with a portable AM radio. If the spark plugs or some other ignition component is making noise you can usually open the hood and pinpoint the source with the portable radio. Fixing the noise can be diffacult.
prcguy
 

mdouble

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Re: Ignition noise from K40 Antenna?

Thanks for all the quick replies. The antenna is mounted via the mag mount base in the center of the roof. Coax from the mount runs back to the rear door which swings out along a horizontal plane, like normal passenger doors. The cable is routed down the door channel in the body then forward through the cargo area. It is tucked in beside the rear seats, then along the carpet edge in the rear footwells. It was then pulled up between the front seats and the center console. It arrives on the floor in the front footwell on the passenger (right) side.

The Midland 75-822 comes with a special harness which replaces the battery back on the bottom of the unit. It is a radio designed for both mobile and portable use. When the radio is equipped with the car adaptor, it has a preconfigured power cord with cigarette lighter plug. This harness also contains the antenna lead. You can find pictures of the radio here if you wish to have a look https://midlandusa.com/product/75-822cb-radio/

I haven't yet tried the antenna in other locations on the vehicle. I had not yet considered the idea of running a separate power line directly from the battery, but will certainly keep that idea in mind. The vehicle is reasonably new so I don't suspect faulty ignition components, but will certainly use the AM radio trick to check for RF from the ignition. Many years ago I had a car which had ignition noise on the radio, so I understand that problem.

I am curious if possibly using the trunk mount option instead of a mag mount on the roof might work. The back door of the vehicle does have a lip on the upper edge which might serve the same function as a trunk on a sedan type car. The trunk mount option on the K40 requires 2 screws to be used which bite into the metal. In theory, this should then ground the antenna to the vehicle. Any thoughts on this idea would also be appreciated. I am new to CB and also studying to get a HAM license. All ideas and the benefit of those with more experience is greatly appreciated.
 

mdouble

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I posted a reply already but may have done so incorrectly. I'm adding this in hopes it will also be seen in combination with the first reply. The ignition noise is clearly the kind of sound associated with RF from a running engine. It accelerates in direct proportion to the speed of the engine. At highway speed, it is a buzz but at idle it is a very clear slower tapping sound. Such a sound was commonplace in cars of the 60's when ignition noise suppression filters weren't working. I started driving in 1965 so have had this problem with radios before and am familiar with the sound of un-filtered RF noise on a radio. I expected a modern CB to have filters to prevent such ignition noise, but obviously I was wrong.
 

mdouble

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Reply to thread re: Ignition noise from R40 antenna

I think any of us that have been around for a while have battled this at some point.

Couple of questions…

Where is the mag mount located on the vehicle, exactly?
- Have you tried moving it around to different locations?

Where, exactly, are you getting your power from?
- Are you tapping into any existing wiring, cigarette lighter plugs, accessory connections, etc?
- Where is the negative lead connected?

How is your coaxial cable routed? Is it running along side any other wiring?

Can you describe the noise you get when the antenna is connected?
- Is it a whine?
- Does the pitch of the whine change with engine speed?
- Is it a constant static?

Before purchasing power line filters, there's some things you can do.
Power should be pulled off the battery. Tapping into existing vehicle wiring, including, but not limited to, the cigarette lighter can be a big source of noise.
Using a short ground wire from the radio chassis directly to the vehicle body can solve some issues. Relying on a long negative power wire or the antenna coax for a good ground can be problematic.

Thanks for your excellent and prompt reply. I posted a reply before, but think I did it incorrectly. I'm unfamiliar with how the form works, so please forgive my ignorance if I got it wrong. I saw the reply posted in the list of threads in the main forum page so I know it actually went there.
 

jonwienke

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I expected a modern CB to have filters to prevent such ignition noise, but obviously I was wrong.

Filters only work if the RF noise is out of band. If the RF noise (or a significant portion of it) is on the same frequency you're trying to monitor, you're going to hear the noise, paricularly on AM.
 

prcguy

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With noise from spark plugs, distributors, etc, you can sometimes hear individual "ticks" from each plug firing when the engine is idling and it turns into a whine at high RPM. The low speed ticks are usually a good indication you are getting noise from the ignition system radiated in the air and picked up by the antenna. Some fuel pumps can make RF noise but its not directly proportional to the RPM. Alternator noise rarely gets radiated where it can be picked up by the antenna but I've seen some old worn out alternators that did radiate.

Some of us ask where the antenna is mounted and how the coax is routed in case you mounted it to the hood above the engine and ran the coax inside the engine compartment were it would be more susceptible to noise pickup. Moving your antenna to another spot will probably not reduce the noise in your case.

At this point you basically need to find what is making the noise and kill it without affecting your engine performance. The portable AM or SW radio is a good tool and you may have to wrap it in metal foil with just a little of its internal antenna exposed if the noise is really bad and it swamps out the receiver at close range.

How old is the Suzuki and do you have any noise on its built in AM/FM radio? Have you ever replaced spark plugs or wires? A new bone stock vehicle should not have any major RF noise, otherwise customers would be complaining about their AM/FM reception. Parts wear out with time and noise can creep in to an older vehicle.
prcguy



I posted a reply already but may have done so incorrectly. I'm adding this in hopes it will also be seen in combination with the first reply. The ignition noise is clearly the kind of sound associated with RF from a running engine. It accelerates in direct proportion to the speed of the engine. At highway speed, it is a buzz but at idle it is a very clear slower tapping sound. Such a sound was commonplace in cars of the 60's when ignition noise suppression filters weren't working. I started driving in 1965 so have had this problem with radios before and am familiar with the sound of un-filtered RF noise on a radio. I expected a modern CB to have filters to prevent such ignition noise, but obviously I was wrong.
 

mmckenna

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Thanks for all the quick replies. The antenna is mounted via the mag mount base in the center of the roof. Coax from the mount runs back to the rear door which swings out along a horizontal plane, like normal passenger doors. The cable is routed down the door channel in the body then forward through the cargo area. It is tucked in beside the rear seats, then along the carpet edge in the rear footwells. It was then pulled up between the front seats and the center console. It arrives on the floor in the front footwell on the passenger (right) side.

So, this raises a few possible issues…

Running the coaxial cable through a door/hatch is going to result in eventual damage to the cable. Damaging the cable can result in higher SWR, water intrusion, or just outright breaking it. More on solutions later.

The other issue is that running coaxial cable alongside other vehicle wiring is a great way to pick up noise from the existing wiring. Keeping coaxial cable away from existing wiring is important, if you must cross existing cable, cross at 90º.

The Midland 75-822 comes with a special harness which replaces the battery back on the bottom of the unit. It is a radio designed for both mobile and portable use. When the radio is equipped with the car adaptor, it has a preconfigured power cord with cigarette lighter plug. This harness also contains the antenna lead. You can find pictures of the radio here if you wish to have a look https://midlandusa.com/product/75-822cb-radio/

Cigarette lighter sockets are great for charing your cell phone, lighting cigarette, etc.
They are awful places to pick up power for radios.
The wiring for the cigarette lighter sockets is bundled in with all the other under dashboard wire, which often includes CAN buss data, blower motors, sensors, HVAC, etc. Great sources of noise. Noise from outside the cabin can get in following existing wiring.

One thing you can try is to feed the radio off batteries. That would allow you to determine if the noise is coming in via the power.

Getting clean power in to the radio is important. If you are serious about getting your amateur radio license down the road, you are going to want a good power feed for your radios. That means fed right off the battery. Cigarette lighter sockets can rarely supply enough current for any serious radios. The noise issue also becomes pretty big.
I'd strongly suggest running a dedicated power feed from the battery into your cabin. Eventually you are going to need it anyway, and it can solve a lot of issues.

Chasing ignition noise when you already have a compromised power feed is sort of pointless.



I haven't yet tried the antenna in other locations on the vehicle. I had not yet considered the idea of running a separate power line directly from the battery, but will certainly keep that idea in mind. The vehicle is reasonably new so I don't suspect faulty ignition components, but will certainly use the AM radio trick to check for RF from the ignition. Many years ago I had a car which had ignition noise on the radio, so I understand that problem.

Don't rule out anything yet, even if it's new.
Could just be a noisy vehicle, some are. Some take a lot of work to make them quiet.

Try moving the antenna around to various points on the roof and see if one works better than the other. That's about the only benefit to magnetic mount antennas, the ability to move them around.

I am curious if possibly using the trunk mount option instead of a mag mount on the roof might work. The back door of the vehicle does have a lip on the upper edge which might serve the same function as a trunk on a sedan type car. The trunk mount option on the K40 requires 2 screws to be used which bite into the metal. In theory, this should then ground the antenna to the vehicle. Any thoughts on this idea would also be appreciated. I am new to CB and also studying to get a HAM license. All ideas and the benefit of those with more experience is greatly appreciated.

Unlikely that is going to fix anything.
DC grounds and RF Grounds/RF Ground Planes are different beasts. They can be the same thing, but a good DC ground doesn't automatically make for a good RF ground.

Also, putting the antenna all the way at one end of the vehicle is going to cause some issues with your ground plane. Your ground plane will be VERY lopsided. Most of the sheet metal will all be in front of the antenna base, which will make the antenna directional.
Sure, CB'ers do it, but it's a lousy way to run an antenna, especially if you are serious about it working well.
The ideal location for any mobile antenna is dead center in the vehicle roof (centered front/rear and left/right). That gives the antenna a nice even ground plane in all directions. Anything else is a compromise.

If you are serious about making the CB work well, you are serious about getting your amateur radio license, and you want all this stuff to work well, then you really must get serious about antennas. Mag mounts are great for temporary use. They are lousy for long term use. The only benefit to them is ease of install/moving. That's pretty much where it ends.

Installing a proper NMO mount in the center of your vehicle roof will give you the ideal ground plane and good ground connection. While it does involve drilling a hole in your roof, it's easy and will not leak if installed per directions.
A NMO mount will give you the best overall performance and the widest selection of antennas. Installing an NMO mount with a CB antenna will work well now. When you get your amateur radio license, you can remove the CB antenna and install an amateur radio antenna, scanner antenna, etc.

The key to all this is making sure all your equipment is installed correctly. Unfortunately for the consumer, the CB radio industry has done a disservice by making users think that plugging into the cigarette lighter plug and dropping a mag mount antenna on your roof is all you need to make it all work.
It's not.
Radio, especially if you want it to work well, requires some more work. Clean power, properly installed antenna, etc. are all key. Plug-n-play works for cell phones, but not real radios. Cutting corners on the install is going to result in poor performance. You can't do the quick/easy install and expect it to work well. There is a reason that public safety agencies spend a lot of money on radio installs in their vehicles. If you want it to work well, you do it right. If lives depend on it, you do it right.
You need to make that decision.
 

mdouble

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Messages
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With noise from spark plugs, distributors, etc, you can sometimes hear individual "ticks" from each plug firing when the engine is idling and it turns into a whine at high RPM. The low speed ticks are usually a good indication you are getting noise from the ignition system radiated in the air and picked up by the antenna. Some fuel pumps can make RF noise but its not directly proportional to the RPM. Alternator noise rarely gets radiated where it can be picked up by the antenna but I've seen some old worn out alternators that did radiate.

Some of us ask where the antenna is mounted and how the coax is routed in case you mounted it to the hood above the engine and ran the coax inside the engine compartment were it would be more susceptible to noise pickup. Moving your antenna to another spot will probably not reduce the noise in your case.

At this point you basically need to find what is making the noise and kill it without affecting your engine performance. The portable AM or SW radio is a good tool and you may have to wrap it in metal foil with just a little of its internal antenna exposed if the noise is really bad and it swamps out the receiver at close range.

How old is the Suzuki and do you have any noise on its built in AM/FM radio? Have you ever replaced spark plugs or wires? A new bone stock vehicle should not have any major RF noise, otherwise customers would be complaining about their AM/FM reception. Parts wear out with time and noise can creep in to an older vehicle.
prcguy

Thanks for your reply. The Suzuki is a 2011, and is very good condition. We have no ignition noise on the OEM AM/FM radio, which I would expect if there was a problem with the usual suspects in the ignition system. That radio works perfectly.

I have a power cord which has two alligator clips and a cigarette lighter socket. My next test will be to connect that directly to the battery then plug in the cb while outside the car using only the factory installed rubber duck antenna. If I get no ignition noise in that configuration I will then connect the R40 antenna. If the R40 has no ignition noise then I will be reasonably certain the noise is coming from the vehicles DC auxiliary power circuit. If however the antenna does pick up noise I think it fair to assume it is somehow picking up a harmonic frequency directly from the ignition. After I've done all that I'll post my results in the forum.
 

garysvan

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the midland 75-822 radio that is being used is not the best cb radio to be used in a car it has no automatic noise limiter (anl) or noise blanker that the better cb radios made to be mounted in a car as a mobile cb radio have. some cars are worse than others for noise. try taking it to a different car and try it. otherwise you can start the project of trying to reduce the noise. sometimes it can be done sometimes it's just does not get much better. some info on cb noise reduction---https://www.google.com/search?client=firefox-b-1&ei=xxOeWp7kE9CN5wLtqJmwDg&q=+cb+radio+noise+reduction+in+a+car&oq=+cb+radio+noise+reduction+in+a+car&gs_l=psy-ab.12...1434850.1441165.0.1442701.10.10.0.0.0.0.593.3389.0j1j0j1j4j2.8.0....0...1c.1.64.psy-ab..2.6.2620...0i8i30k1j0i22i30k1j33i22i29i30k1.0.hFQkNnzFxHo
 

mdouble

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Re: Midland 75-822 and related issues with K40/Ignition Noise

Thanks for your reply. The information you offered has been a great help. Aside from the Midland 75-822 I also have a Uniden Bearcat 980SSB. I used the Bearcat as a home base station, which I power using a small 12-volt battery. After reading your reply I put the Bearcat in the car connected to the same K40 I used with the Midland. After turning on the ANL feature on the Bearcat the ignition noise disappeared. RX and TX were noticeably improved with the Bearcat, even in a temporary setup.

As a side note, I also did another test using one of the two Midland 75-822 radios I have. This one is set up with a portable battery pack which allowed me to walk around the Suzuki with the engine running. It very clearly picked up ignition noise with the OEM rubber duck antenna. Approaching the vehicle made the noise louder and this was present on all channels with both RX and TX. Clearly, the Suzuki is producing a good deal of RF noise from some source, potentially, as was suggested, directly from the plugs.

It seems the short quick solution to the problem is to buy another mobile radio with an ANL feature. I'll just use the Midland radios as handheld portable units. I'll do some investigating to see if I can find a solution to reduce or eliminate ignition noise. At this moment I'm not overly hopeful such a solution will be simple or cheap. I will share any information or solutions I might come across for the benefit of others who may have a similar issue. I will keep you posted on my success in getting a better radio for mobile use.
 

Rred

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Does the car have the original spark plug wires and other ignition parts?

When cars have traditional "resistor" wires to cut ignition noise, the wires can start out being 50 ohms when they are new, and over the course of four or five years increasing to 20,000 ohms, at which point they are inefficient (hurting engine performance and mpg) and allowing more ignition noise as well. If you unplug any of the wires and use an ohm meter to check the resistance of the center core from end to end, it should be no more than ~5000 ohms. If any of them are higher, consider first doing a major tuneup, which the car may need anyway. Similarly check the spark plugs for visual damage. I had a friend with an old Chrysler that "wasn't running so well" and in fact had eaten two of the six spark plugs. Incredible that it was still running at all, but sometimes the ceramic jacket on a spark plug cracks, or is bridged by grease and oil films. I can't guess at what else might contribute to generating noise, there are so many different ways they build engines these days.
I know there is no more manufacturer support in the US, but a shop or owner's group that is familiar with Suzuki's might know if this is a common issue for that model, with a specific solution.
 

mdouble

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Re: checking resistor wires as source of RF ignition noise

Thanks very much for your suggestion. I have a very good local mechanic I can consult about spark wires and the related bits of the ignition/electrical system. I will go have a discussion with him when I have the car in for an oil change next week. He may have some additional thoughts on the matter. That was a very good suggestion.
 

SCPD

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Do you get the noise on a blank AM broadcast radio frequency in the car?
I would change your wires,and sparkplugs or coilpacks.....depending on the car.
Get a CB with Noise Blanker and ANL.
Try the antenna on the trunk see if that helps.
 

mdouble

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Re: checking resistor wires as source of RF ignition noise

Hi Radio Sunshine, and thanks for the suggestions. I don't have any RF noise on the car AM radio. I've done some fiddling around and pretty much figured out that the RFI on the CB is from the antenna, not from the cars 12V power supply. I used a handheld Midland 75-822 CB and walked around the vehicle with the engine running. I turned off the squelch entirely, but the unit on Ch 2 and went 15 feet away in front of the car. As I approached the vehicle I could detect RFI from the engine at about 10 feet. This grew louder as I got closer. This RFI noise was being picked up via the rubber duck antenna on the Midland. I am not using the Midland in the car now, as was the case before. As I circled the vehicle and could detect the ignition RFI in all directions. I replace the Midland with a new President CB. and this is connected to a K-40 with a 52-inch steel whip. The SWR tests at exactly 1.0. The antenna is mounted on the roof via a magnet mount base, and os pretty much mid-vehicle. I've been using the NB feature on the President which helps cut out the ignition RFI. However, I'm still looking for a way to stifle RF entirely if possible. I've seen a lot of different ideas in this forum and elsewhere. Some of these include bonding various components of the vehicle to a grounded part of the chassis. Apparently, the exhaust system can act as an antenna for engine RFI. As far a moving the antenna is concerned this might be an option. I have a Suzuki Grand Vitara, which is an SUV. The rear door swings out horizontally as would a normal passageway door. However, it does have an upper lip where it might be possible to use the trunk lip mounting bracket to put the antenna at the very back of the vehicle. This mounting position would be my last option.
 

ladn

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Try an engine compartment inspection. Look for corrosion or loose connection on any bonding straps between the body/frame/hood.

Also look for cracked or loose ignition wiring.

And, lastly, try a different grounding point for your radio.
 

SCPD

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Recommend

Heres what I recommend:
Run a dedicated power cable from the car battery to the radio Directly,avoid running the power wire
near the engine and firewall by the windshield as much as humaly possible.Ground the radio to the Metal frame as close as possible to the radio,scratch all the paint away and use a soldered eye hook connector.
I think you are using a cigarette lighter plug, am I right?

I have a Wilson 1000 and a K40 and neither make any noise on my Uniden Grant DX.
Its electrical noise definately.
Could need new spark plugs and wires or coilpaks if you hear "ticking"Put-put put when you rev the engine if it gets faster thats what it is.

The vehicle computer is usually by the passenger kick panel avoid that at all costs.No coax wire near it .
That makes noise like crazy if you are running wires near him.

Kudos and see you on the air.

Red Ryder somewhere around the Garden and I'm back quiet.
 

mdouble

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Thanks for all the great suggestions, all are useful. The first step I will take to begin resolving the issue is to revisit my local mechanic. I've already had a discussion with him about the RFI issues. He has some experience with radios because he's installed radios in county vehicles. As has been suggested here, he directly wired the power supply to the radio via a dedicated line to the battery. He's also familiar with bonding and grounding. I get the fact that a properly installed antenna is key to good RX and TX with any radio, either CB or HAM, but getting maximum performance requires attention to detail and getting everything just right. I'll continue working on the noise issue until I find a solution. As a side note: Yesterday I did a distance test and as able to get good RX and TX at 7.24 miles from the base station using SSB. As a temporary solution to the engine RFI noise problem I did each test with the vehince stopped and the engine off. Obviously this is not the ideal circumstance, but I was also testing the RX and TX of the base station antenna, which is a Workman atop a 35 foot mast using 50 ft of good quality coax cable. This antenna does not require a ground plane is is designed for use with a 50 ft cable run. I was pleased with the initial test, but obviously, want to squeeze as much distance as possible out of these 2 radios.
 
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