Vhf Noise Suppression

[emergpa1]

I have an MPPT 500 solar panel charge controller. I am getting noise over my VHF radio. I have researched the problem and found some post that recommended the following. I was hoping i could get some more details on these modifications

The poster stated, "BZ has made a couple of suggestions, the first was a "filter" in the supply line from solar panels and was a dyi coil of single strain #10 wrapped around a piece of rebar. Did not have any affect. The current recommendation if to install a CB radio filter in the solar panel supply lines to the controller."

I was wondering if anyone had success with this (the thread did not give a final post from the author saying if this worked or not, the thread was old, and on another forum, and appeared abandoned) and if so, what size or type of VHF noise suppressor was used, and where was it mounted?

Thanks
keith

 

[emergpa1]

here is a photo of the controller

 

[py26129]

Keith

I also had noise issues with my VHF. At times it was very difficult for others to understand our transmissions. I never managed to pin down the exact cause but ended up replacing theVHF with a $70 unit, bought on sale. This fixed all our issues.

Matt

 

[arf145]

I had a VHF RF noise problem that started when I put in some LED lights, so I knew the problem was the electronics in the lights. I decreased the noise interference by putting ferrite core filters around the light supply lines.

 

[Forrest15112]

It sounds like poor or faulty filtering in the solar controller. I would try looping the power leads through a ferrite core first and then possibly installing filter on the power wires. Make sure the radio is grounded too. You should be able to find a filter at Radio Shack. Just ask for something to eliminate 'alternator whine' and they should be able to help you. Keep in mind, how much current your radio draws and get something suitable. The ferrite cores should be available at Radio Shack too.

 

[Bill Roosa]

Go to acvance auto parts or similar. buy an "alternator noise suppression capacitor. Looks like a 0.75" long metal cylindar with one wire. Ground the cap body to your radio near the power connection and connect the wire to the positive power supply. The closer you can attach the cap wire to the radio the better.

 

[Forrest15112]

The more I think about this, the more I'm inclined to believe it's not a filtering issue on the dc supply, but possibly RF noise. It may be generated by the controller if it is microprocessor controlled. Something to look for would be a good ground on the controller chassis, as well as the VHF and does the antenna coax run parallel along with any power cables. I'd still try the filters too. Does the noise go away if you turn off the controller? Shore power AC chargers are notorious for lack of filtering and create noise on dc, but your solar panel & controller is dc. An inverter left on can do this too. Good luck finding the source

 

[Brian D]

I am assuming that this a receive issue and not noise on your transmit.

I agree with Forest. This sounds much like RFI. But you have to find out where the RFI is coming from. If you know anyone who has a spectrum analyzer (dc to 1000 MHz) you will be able to trace down the source of the RFI. You might be able to invite a Satellite Installer who has a spectrum analyzer, or if you have any ham radio friends.

RF works on sine waves and the are AC in nature, not DC. So I would start by disconnecting the AC source (dock). Then any inverters you have. Someone mentioned that the solar panels are DC. That is correct so there should be no noise what so ever from them.

Also check the shielding on the RF cable. If it is broken, it could act as an antenna itself.

One other possibility is to use a hand held radio. Putting the radio close to the source will generate a great deal of noise on the radio.

 

[Bill Roosa]

I have to disagree with you Brian. If the solar has a charge controller it has PWM waveform in the MHz range. So while the average at the batteries is a steady DC voltage the unit is sending a pulse modulated at high frequency. They do cause RF interference.
The easy way to check where the interference is coming from is to disconnect the VHF antenna feed from the radio. if you still can hear it then it is on the power circuit. If not then the antenna circuit is to blame

 

[emergpa1]

I have to disagree with you Brian. If the solar has a charge controller it has PWM waveform in the MHz range. So while the average at the batteries is a steady DC voltage the unit is sending a pulse modulated at high frequency. They do cause RF interference.
The easy way to check where the interference is coming from is to disconnect the VHF antenna feed from the radio. if you still can hear it then it is on the power circuit. If not then the antenna circuit is to blame

i think you are right bill, when i pull the fuse on the solar panel controller, the reciever noise quits. also it is gone at night.

i have been in contact with the control manufacture, BZP inc, and he sent me the following reply promptly:
"a 50uH inductor in the PV+ line usually knocks down all RFI. A "CB" noise noise filter in the PV line is also very effective. New production MPPT500 controls incorporate a .1uF 400 volt capacitor wired between the BATT- terminal and the chassis ground point. We have a marine VHF radio with 9DB antenna next to the calibration station. We rarely break squelch"

I ordered a "noise filter" and sent him a photo and asked him how to wire it in and he replied:
I would wire Radio+ to the solar panel, Battery+ to the control and neg to Battery-.

what do you guys think?

 

[Jimm]

I have had no interference from the installation of a 140W solar panel and controller (which is mounted adjacent to my VHF radio), but I have severe interference from my LED anchor light....... Anyone have similar experience/solution with the anchor light?

 

[Maine Sail]

I have had no interference from the installation of a 140W solar panel and controller (which is mounted adjacent to my VHF radio), but I have severe interference from my LED anchor light....... Anyone have similar experience/solution with the anchor light?

Solar controllers and LED lights can cause RFI. Cheaper LED lights & controllers especially.

If this is a standard "USCG Certified" anchor light by AquaSignal, Hella or any other reputable manufacturer this should not be an issue. If this is a home made nav light, with an aftermarket bulb, most of them don't incorporate any sort of noise suppression so you'll need to address the noise on your own or by turning it off when doing TX.

 

[Brian D]

Thanks, Bill. However, it is still an RFI issues and not a power issue.

I have read up on PMW Waveform as well as SPMW and see that there are issues with this waveform on the side of suppressing harmonics. It appears to squeak by FCC requirements for suppression of stray RFI. It is unfortunate that it sounds like the product was not engineered correctly. I am wondering if this product was really designed for marine use. I saw where the company uses a VHF radio for testing purposes.

Keith, did the manufacture send you the filters or do you have to purchase them on your own?

Regardless, I am glad the problem has been located and hopefully the solution will clear up your VHF issues.

Oh, I should add that since Keith can remove his antenna and the noise goes away, that also means that Keith's boat is causing willful interference to vessels near his boat. That is an FCC violation and Keith could be held responsible. Not saying that will happen, Keith, but it is an issue.

 

[emergpa1]

Thanks, Bill. However, it is still an RFI issues and not a power issue.

I have read up on PMW Waveform as well as SPMW and see that there are issues with this waveform on the side of suppressing harmonics. It appears to squeak by FCC requirements for suppression of stray RFI. It is unfortunate that it sounds like the product was not engineered correctly. I am wondering if this product was really designed for marine use. I saw where the company uses a VHF radio for testing purposes.

Keith, did the manufacture send you the filters or do you have to purchase them on your own?

Regardless, I am glad the problem has been located and hopefully the solution will clear up your VHF issues.

Oh, I should add that since Keith can remove his antenna and the noise goes away, that also means that Keith's boat is causing willful interference to vessels near his boat. That is an FCC violation and Keith could be held responsible. Not saying that will happen, Keith, but it is an issue.

Thanks for the heads up Brian.

You did say "remove antenna", but it actually goes away if I remove the fuse for the controller and disabling the solar panels. And at night after the sun goes down.

I'm still in north ga working, and have not had a chance to hook up the noise suppressor. I had to purchase it on my own. I'll post the results in about 10 days.

Thanks for the help!

Keith

 

[BigEasy]

Turn on all electrical / electronic equipment and one by one turn off each piece of equipment while the VHF remains on. You can use an AM portable AM radio set set on an unused channel while being placed close to the suspected source; the characteristic sounds will be heard from the portable radio speaker. You really need to pin point the source of the interference before arbitrarily attempting to suppress various components. Once, the source is found, you can using grounding, ceramic or coaxial capacitors, RF chokes, or shielding to minimize the noise.

Its possible in an older rig, that much of the noise may be from the antenna, coax, or the VHF. You should also test away from the marina as other boats and buildings may be causing some of the interference. Recently completed a US Power Squadron course in Marne Electrical Systems; there was an entire section that was dedicated to interference and suppression. Excellent course if you have an opportunity to take it. Hope this helps.

 

[emergpa1]

Keith

I also had noise issues with my VHF. At times it was very difficult for others to understand our transmissions. I never managed to pin down the exact cause but ended up replacing theVHF with a $70 unit, bought on sale. This fixed all our issues.

Matt

thought about that matt, but we bought a handheld vhf and it has the same noise, anywhere in the boat, during the day, with the fuse in the charge controller. at night or with fuse out, it goes away.