# Electric interference on CB??



## dtbaker (Jan 5, 2008)

could just be the power source. is the cb powered from dc-dc, or have a battery/capacitor in between the controller and CB? you could test by powering the CB off a standalone battery....


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## Tesseract (Sep 27, 2008)

Yeah, Mike, EV motor controllers can produce a lot of RFI as a result of switching high voltages/currents in short amounts of time (it's not so much the switching frequency that causes noise, it's the switching speed).

There are lots of things to try, but I'd start with a very simple one first: see if a portable AM radio picks up the interference too. AM radios work exactly the same as CB radios but at a lower frequency so the noise should be WORSE. By using a portable radio you will ensure that it is the antenna picking up the noise rather than coming in through the power leads.

If the portable AM radio doesn't pick up any noise (or very little - it's virtually impossible for one to not experience some interference from a motor controller) then the noise is getting into your CB through it's power leads. You need to start trying those various power line filters they make specifically for CBs (or get a different CB). My bet is that this is what will actually solve the problem, but you never know with these RFI problems...

If none of that helps then the next steps really require professional intervention. I have several books on just this subject - we're talking 350+ page tomes, here - so I can't possibly cover it in a post, but I will say that a client of ours in the Netherlands was able to successfully get a Soliton Junior powered EV through their very strict EMC testing process so it is possible.


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## m38mike (Dec 27, 2008)

Thanks for the ideas Dan and Jeffrey. I'll try the AM radio to see what happens. The power for the CB comes from my 12v battery through a fuse block and straight to the radio. The other fuses in that block are for my emergency flashers and the horn. 

Would Radio Shack carry the power line filters that you both refer to?


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## Tesseract (Sep 27, 2008)

A better way to see if the noise is coming in from the antenna or the power leads is to simply unplug the antenna from the CB radio. If the noise doesn't change in volume then it's coming in through the 12V power supply. A noise filter will help in this case.

I don't know if Radio Shack carries these things anymore, but any place that sell car stereos should. One important thing: higher current is NOT better for a noise filter - try to get one with just a little bit more current rating than the CB draws when transmitting at full power (should be less than 10A). 

CB radios are infamous for picking up alternator and ignition noise from ICE vehicles, BTW, but some are worse than others. Like I said before, you may have to try a different brand or model, or even a battery-powered handheld version.

Helpful article on fixing a noisy CB

Noise filters at Radio Pro Shop

Pyramid NF12 at Amazon.com


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## m38mike (Dec 27, 2008)

I checked the radio and my interference is coming in through the power wires, not the antenna coax. Or at least most of it is. So I've ordered noise filters to put on the power wire to see if that will quiet the static. I appreciate the reference links to the filters. Thanks.


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## m38mike (Dec 27, 2008)

I picked up a couple NS-12 inline noise filters from Amazon to see what they would do for me. I got a little quieting from one on the line. I'm going to try a second one in series with the first one to see if the pair will make even more improvement. Or would it be better to have them in parrallel?

One of the thoughts I had while looking at my setup was wondering if putting the CB in a grounded metal container and just having the mike and an external speaker outside the container, would that clean up the static? I would think that a grounded metal container would shield the radio itself pretty well. 

Any thoughts on those ideas? Any experience?


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## GW0DIV (Jan 3, 2011)

Try wrapping the wires around some ferrite, either torroid or clip on. Try finding a friendly local radio ham who might be interested in helping.


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## m38mike (Dec 27, 2008)

I talked with a long-time radio guy and he recommended I try a couple of things. 1st is to replace the power/ground wires to the radio with RG-8 coax. I picked up a piece that should work for me from my local radio shop. He said to keep the 3 filters I currently have inline in place just before the CB, but to check to make sure I'm getting enough voltage to the radio. With the filters in line, if the motor isn't turning, then the radio has no interference. Without the filters, the rest of the electronics create enough interference that I have to turn the squelch up over half way in order to cancel the noise. 

The second thing he said to try was to wrap the radio in foil a couple of times to see if that cut down on the radiated interference. If that does help, then I may see about mounting the radio in a steel box, like an ammo can, and grounding it. So i've got some experimenting to do this weekend.


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## piotrsko (Dec 9, 2007)

you'll will need to ground one side only of the RG-8 outer shield wire to either the radio (preferred) or to the ground (chassis) of the car.

it won't dissipate much heat, but over a while the radio will need some cooling in the can.


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## m38mike (Dec 27, 2008)

I tested the "radio in a can" idea. It failed. I used an RG-8 coax to bring power straight from the 12v battery to the ammo can the radio was in. I grounded the coax shield to the can, which was grounded to the steel body of the jeep. The antenna coax also came into the can. And I had three NS-12 line filters in series on the power wire just before the CB. The radio was very quiet with everything else turned on and running, but once I started turning the motor there was too much static to use the radio. So at this point, I can use the CB when the EV is not moving, but I need to turn it off when I am moving. 

My next course of action is to contact Netgain to see if they have looked at this problem and found a solution.


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## aeroscott (Jan 5, 2008)

i remember something about grounding both ends of the shield or just one end .


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## Tesseract (Sep 27, 2008)

m38mike said:


> ...
> My next course of action is to contact Netgain to see if they have looked at this problem and found a solution.


What brand/model CB radio is this? Have you tried a different CB (even a handheld portable one)?

Secondly, you might want to try running the motor directly from a 12V battery and see if the noise persists (make sure you disconnect at least one of the motor leads from the controller and don't forget to put the transmission into neutral first). If so then it is likely the motor brushes at fault, but I'd put my money on the motor wiring/controller.

Looping both 12V supply lines to the CB through a ferrite core (the clamp kind from Radio Shack are acceptable) is usually helpful.

Connecting (3) 0.1uF/600V film capacitors to the motor terminals (one between the terminals, and one from each terminal to the motor case) can be helpful, but be advised that this results in AC currents flowing into the vehicle chassis. 

Placing the motor cables inside a metal conduit fully grounded at both ends (ie - to the controller one end and the motor on the other) might be helpful.

Etc. and so on. 




aeroscott said:


> i remember something about grounding both ends of the shield or just one end .


You only ground one end of the shield to break frequency ground loops; at radio frequencies you ground both ends of the shield, if not as many points along the shield as possible.


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## m38mike (Dec 27, 2008)

Tesseract said:


> What brand/model CB radio is this? Have you tried a different CB (even a handheld portable one)?


My primary CB for this vehicle is a Uniden XL510. My alternate CB is a Midland. Yes I used two different CBs, both hard wired to the 12v system. Both had the same intereference problem when the motor turned. I don't have a hand-held CB and don't know anyone who does. I'm going to try using a handheld FMRS radio to see if it has problems.



Tesseract said:


> Secondly, you might want to try running the motor directly from a 12V battery and see if the noise persists (make sure you disconnect at least one of the motor leads from the controller and don't forget to put the transmission into neutral first).


This is a good thought, and perhaps a good test. When I ran my power through an RG-8 coax with the shielding grounded to the radio, and connected three NS-12 filters between the coax and the radio, I filtered out all the intereference except what was coming from the motor. If I did not touch the accelerator, then the radio was quiet and recieved well. As soon as the motor started turning, the static was back.



Tesseract said:


> If so then it is likely the motor brushes at fault, but I'd put my money on the motor wiring/controller.


What??!! You'd bet against your Soliton Jr?? Now that raises an interesting question, have you checked or tested the Junior for RFI?



Tesseract said:


> Looping both 12V supply lines to the CB through a ferrite core (the clamp kind from Radio Shack are acceptable) is usually helpful.


The radio is grounded through it's mount, and the connection to the steel body of the jeep. So the only wire coming in is the power wire, currently an RG-8 with the shielding grounded at the radio. Would this ferrite core still work on the RG-8?



Tesseract said:


> Connecting (3) 0.1uF/600V film capacitors to the motor terminals (one between the terminals, and one from each terminal to the motor case) can be helpful, but be advised that this results in AC currents flowing into the vehicle chassis.


I really don't think I want to introduce AC currents into my chassis. I use it for my 12vdc ground. I don't think I'll try this.



Tesseract said:


> Placing the motor cables inside a metal conduit fully grounded at both ends (ie - to the controller one end and the motor on the other) might be helpful.


I've wondered about this too.  I currently have them twisted together for thier 6 foot length from controller to motor. I could put them in flex-conduit. But here's a question, should they both be in one conduit or in separate conduits?



Tesseract said:


> You only ground one end of the shield to break frequency ground loops; at radio frequencies you ground both ends of the shield, if not as many points along the shield as possible.


For the RG-8 that's providing the power to the radio, it's grounded at one end, on the radio. And it's a dedicated wire direct from the 12v battery. The antenna coax is grounded at the radio and at the antenna end. When I removed the antenna coax from the radio, the interference I heard was the same as when the coax was connected. This told me that the interference was either coming in through the power cable, or directly into the radio itself. By adding the 3 filters inline, I've eliminated the weaker interference that came in through the power wire. Now it's time to see what I can do with the motor RFI. 

I contacted George Hamstra, Netgain Motors, and he said he'd work on this issue. I was the first person to bring this problem up. I guess I'm a trouble maker. I think it's because most folks don't use CB radios anymore. I need to be able to use a CB on my upcoming trip to the Yukon and Alaska. I think if we can solve this problem, there are quite a few Ham operators that will be glad, based on conversations I've read on some radio forums.


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## Tesseract (Sep 27, 2008)

m38mike said:


> What??!! You'd bet against your Soliton Jr?? Now that raises an interesting question, have you checked or tested the Junior for RFI?


Our controllers have not been formally tested, no, but I employed good engineering practice concerning RFI when I designed them. Actual RFI testing is prohibitively expensive - we were quoted $1500 per day with a 4 day minimum to have informal "pre-compliance" testing done (not even usable for FCC or CE certification!) or $12,000 per controller for the full monte. That's why you don't see FCC certification labels on any other EV motor controller either...

Also, actually meeting RFI compliance with an EV motor controller would depend greatly on its installation, especially with regards to the HV cabling. The battery cables benefit most from being twisted together (ie - run the + and - as close to each other as possible from pack to controller) while the motor cables benefit most from being placed inside a metal conduit. 



m38mike said:


> The radio is grounded through it's mount, and the connection to the steel body of the jeep. So the only wire coming in is the power wire, currently an RG-8 with the shielding grounded at the radio. Would this ferrite core still work on the RG-8?


No, in this case the ferrite would just block RF currents from traveling along the shield. Ideally you'd want to ditch the RG-8 and loop *both* power leads for the CB through the ferrite several times because then the ferrite will only see the common mode current (ie - the noise); looping just the positive lead through the core will still block noise, but the core sees both the current drawn by the CB as well as the noise current so it will be more prone to saturation.

(See why I said things quickly get so technical you have to hire an engineer?)



m38mike said:


> I've wondered about this too. I currently have [the motor cables] twisted together for thier 6 foot length from controller to motor. I could put them in flex-conduit. But here's a question, should they both be in one conduit or in separate conduits?


It would be best if they are in the same conduit. The conduit needs to be electrically bonded at both ends (ie - to the controller enclosure and motor housing).



m38mike said:


> By adding the 3 filters inline, I've eliminated the weaker interference that came in through the power wire. Now it's time to see what I can do with the motor RFI.


If your CB radios were picking up noise *before* you added the inline filters, and without the controller turning the motor, then it sounds like you have a bad ground connection for the 12V battery, or, perhaps, a missing bonding strap between frame/body sections in the vehicle. You might want to try pulling the radio from the dash and running a separate wire from the (-) post of the battery all the way up to it and see if that helps (just temporarily, of course).


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## m38mike (Dec 27, 2008)

Tesseract said:


> Our controllers have not been formally tested, no, but I employed good engineering practice concerning RFI when I designed them. Actual RFI testing is prohibitively expensive - we were quoted $1500 per day with a 4 day minimum to have informal "pre-compliance" testing done (not even usable for FCC or CE certification!) or $12,000 per controller for the full monte. That's why you don't see FCC certification labels on any other EV motor controller either...


WOW! That's a chunk of chainge for little added benefit. I can see why that's not persued. 



Tesseract said:


> Also, actually meeting RFI compliance with an EV motor controller would depend greatly on its installation, especially with regards to the HV cabling. The battery cables benefit most from being twisted together (ie - run the + and - as close to each other as possible from pack to controller) while the motor cables benefit most from being placed inside a metal conduit.


AHA!! You may have hit on a possible lead here. My motor cables are paired up between the controller and the motor, about 6 feet. But my battery pack cables do NOT come together until they get to the controller. The Junior is mounted between the two halves of my battery pack. The positive comes from the rear battery box and the negative comes from the front battery box. Totally opposite ends of the EV. The cable that connects the two halves of the pack does run next to the pack negative for part of it's length, and next to the pack positive cable for part of it's length. But they are not twisted, simply paired up with zip ties.



Tesseract said:


> No, in this case the ferrite would just block RF currents from traveling along the shield. Ideally you'd want to ditch the RG-8 and loop *both* power leads for the CB through the ferrite several times because then the ferrite will only see the common mode current (ie - the noise); looping just the positive lead through the core will still block noise, but the core sees both the current drawn by the CB as well as the noise current so it will be more prone to saturation.


It sounds like the ferrite would do for me what the in-line filters are already doing - cleaning up the signal. Unless you think that it would be capable of cleaning up the motor RFI as well, I'm not sure it would help me any more than the filters have so far.



Tesseract said:


> (See why I said things quickly get so technical you have to hire an engineer?)


Precisely why I'm so engaged in this exchange of ideas. I'm enough of an engineer to know when I need the help of better engineers and better specialists in fields I know only marginally. 



Tesseract said:


> If your CB radios were picking up noise *before* you added the inline filters, and without the controller turning the motor, then it sounds like you have a bad ground connection for the 12V battery, or, perhaps, a missing bonding strap between frame/body sections in the vehicle. You might want to try pulling the radio from the dash and running a separate wire from the (-) post of the battery all the way up to it and see if that helps (just temporarily, of course).


Good thoughts, but I don't think the ground is the problem. I have the 12v battery in a steel box that is part of the body of the jeep. From the battery negative I have a 1/0 cable that connects to the frame. I also have a strap that connects the negative terminal to the battery box/body. The whole body is made of 18 gauge sheet steel, and paint. No plastics. And there are 10 bolts that hold the body and frame together that also help with the grounding connection. So grounding should not be a problem on the 12v side.

What I do plan to do next is put a separate small 12v battery in the box with the radio to see if that helps any. That would give the radio a dedicated power source that is right next to the CB. Nothing would be outside the can except the antenna coax and antenna. 

I also plan to try my handheld FMRS radios to see if they get interference. I might even go park Electro-Willys next to my pickup to see if it interferes with the CB in the pickup, or the AM/FM radio. I'm curious to see just how big this fuzzball of electronic noise is that I've created. I'm hoping the apparent motor RFI is not so strong that it's coming in through the antenna. But I have not ruled that out. My test for that will be to remote the antenna with an extended coax to the far side of a small steel building so the antenna is shielded from Electro-Willys. 

Wish me luck!


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## GW0DIV (Jan 3, 2011)

Try having a look at K0BG's site, you should find it through eHam, he's a mobile radio guru.

Rhys


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## m38mike (Dec 27, 2008)

Well, the battery-in-the-can idea didn't work any better than the radio-in-a-can idea did. With both the radio and a battery in a closed metal container, I still got static when the motor turned. Otherwise the radio was very quiet. If Netgain can come through with an idea about how to quiet the rfi from the motor, then I'm good. Without that I will not be able to use the radio while driving, only while stopped.


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## JRoque (Mar 9, 2010)

Hi. To figure our if it's coming through the power cables run your CB from a small standalone battery (don't TX). To see if it's RF, run a jumper wire from the center of the PL259 to the outer thread (again, no TX).

If it's DC carried, your DC/DC is probably not isolated as it should be or it is defective. You might also want to reposition the DC/DC away from the controller and as close to the pack as possible.

If it's RF noise, twist the motor cables or as suggested, run them through a metal conduit grounded at both ends. Using a plastic soda 2 liter bottle, loop the coax 8 to 10 times around it, tie down or glue it and remove the bottle. You can never have too many beads on your wires.

I'll assume you've tried switching on the radio's NB.

JR


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## piotrsko (Dec 9, 2007)

at this time I hate to report; listen to the AM stuff on your radio. if it is the same as the CB, then the arcing on the motor is at fault and you are the recipient of broad band radiation, which in this case will be really hard to remove. Pretty sure that nothing on the controller will help, the only possibility would be an extremely efficient narrow pass filter for the 10 meter band. The only way you could have controller reprieve would be to have a tone that varies in relation to the controller output or gas pedal stomping.


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