Blue Sea Dual USB Causing RFI - Any Solutions??? (1 Viewer)

[bulldog1402]

Before putting in the Blue Sea Dual USB, FM radio reception was good.

Install of the Blue Sea was a breeze and I was very happy. I listen to music via an Aux In. Music from my iPod plays perfect, no static or whine.

Since the install of the Blue Sea, my FM radio reception is terrible. No alternator whine or anything, just don't receive signal as well as before the install.

I understand that this happens with some charging cables, etc, but are there any solutions to this problem other than not listen to the radio?

 

[scrowley]

You prob. Have your power feed running to close to the antenna wire or other stereo wires causing interference. To test this assumption you can disconnect current power source then run a temp in a diff. Location. See if noise persists.

 

[bulldog1402]

I have no stereo wires even close to it and the radio antenna is far away too.

I guess I could try some brand new lines just to rule out issues due to locations of the wires I used.

 

[george_tlc]

USB converters have to step 12V down to 5V. They do that with a switching DC to DC converter. Lots of of nasty switching currents that without shielding and ferrite magnetics on the power leads WILL create EMI.

Changing you wire type won't help. You can try a better ground path. You can try to find a ferrite toroid or snap on ferrite filter to put on the leads to the USB unit right near the unit. Loop the leads through the toroid or snap on ferrite 3 or 4 times. That will help prevent EMI conducting down the power cable.

Some EMI may also be radiated, that depends on the shielding of the DC to DC converter. Even some Al foil can help with that (ground the foil).

Anyhow, you'll need to experiment... or stop using the FM radio and stream your own music

cheers,
george.

 

[bulldog1402]

I listen to the radio maybe 10% of the time. Might be too much work for little payout/reward.

Thanks for the great information. The problem with the Blue Sea is that it is always on (so to speak). Maybe I will throw a switch in there so I can turn off the power when I want to listen to the radio. That seems to be my best option (read easiest).

 

[Timpanogos Slim]

huh, I absolutely don't have that issue. dual USB in the shifter console and a kenwood HU. No difference in FM reception.

My dual usb socket gets it's power from the back of the factory cig socket, fwiw.

 

[Qball]

I have similar problem with my sub amp. I have lots of noise from the RCA cable from back of the HU.

Checked ground and it is good, only have noise when engine is in. My amp is cheaply be that's why but I don't think it is the amp.

 

[bulldog1402]

Yeah it's definitely not an amp or RCA issue. It only reared its ugly head after the Blue Sea install.

I don't think another power source will aid. I have tried two separate ones already.

 

[Timpanogos Slim]

So, right now the charger is always powered.

I'm gonna put my two bits on the issue being in the antenna wiring itself, and having nothing to do with the charger.

 

[bulldog1402]

The antenna worked just fine before the Blue Sea went in. Antenna was working perfectly.

 

[LandCruiserPhil]

I would call Blue Sea and talk with the technical department. They are very knowledgeable and have been super helpful to me in the past.

 

[Timpanogos Slim]

The antenna worked just fine before the Blue Sea went in. Antenna was working perfectly.

Did you have the head unit out at all? Were any wire harnesses moved around during the install?

Does the reception get better or worse if the antenna is up or down or someone is touching it?

I'm guessing that the first answer is "maybe" and the 2nd answer is "no".

But I'm not there to hear what your radio sounds like. I just find it unlikely that a dc-dc converter would interfere with FM.

AM, sure.

 

[george_tlc]

EMI is a signal to noise ratio (SNR) issue. What works great (on FM) with a strong signal is a different story with a weaker signal where the EMI becomes a large contributing factor to good reception. AM tends to be even more sensitive to EMI and weak signals.

So, what works well for one person's vehicle/area may not for another.

EMI also can have radiated components and conducted components. So, depending on grounds and wiring and location of source/target reception can be worse or better.

There's no magic solution other than trying various things to see what improves the situation or not.

cheers,
george.

 

[Timpanogos Slim]

EMI is a signal to noise ratio (SNR) issue. What works great (on FM) with a strong signal is a different story with a weaker signal where the EMI becomes a large contributing factor to good reception. AM tends to be even more sensitive to EMI and weak signals.

So, what works well for one person's vehicle/area may not for another.

EMI also can have radiated components and conducted components. So, depending on grounds and wiring and location of source/target reception can be worse or better.

There's no magic solution other than trying various things to see what improves the situation or not.

I'm just figuring that the switch in the bluesea unit is running somewhere between 50khz and 1mhz, and i cannot fathom where it would produce RF that would cause an issue. For FM.

I've had FM tuners installed inside of computers that worked just fine.

Now, if there's a conducted element, that i could understand.

Thing is i do not remember at all whether i grounded my bluesea usb socket to the cig socket or to the body. I can see myself doing either.

What makes me suspicious is the framing of this as a reception e.g. signal strength issue vs. an interference issue. The HU or the USB lacking a really good ground could cause some issues.

I fought with bad reception for a long time in one of my cars before i got behind the stereo and found that the itty bitty fakra connector on the factory harness was shattered.

It was absolutely a "Well there's your problem" moment.

 

[george_tlc]

I'm just figuring that the switch in the bluesea unit is running somewhere between 50khz and 1mhz, and i cannot fathom where it would produce RF that would cause an issue. For FM.

I've had FM tuners installed inside of computers that worked just fine.

Now, if there's a conducted element, that i could understand.

Thing is i do not remember at all whether i grounded my bluesea usb socket to the cig socket or to the body. I can see myself doing either.

What makes me suspicious is the framing of this as a reception e.g. signal strength issue vs. an interference issue. The HU or the USB lacking a really good ground could cause some issues.

I fought with bad reception for a long time in one of my cars before i got behind the stereo and found that the itty bitty fakra connector on the factory harness was shattered.

It was absolutely a "Well there's your problem" moment.

I guess you've not heard about harmonics then...

You can easily get harmonics going up into the 100MHz range from switchers running at a few hundred KHz. I've seen them with LED drivers (which is my bread & butter)... Spectrum analyzer lets you see all the nasty stuff that can come out of a switcher (radiated & conducted). It's a fascinating subject and can be equally frustrating too

cheers,
george.

 

[Timpanogos Slim]

I've heard of harmonics. just doubtful is all.

i think this is our first report of an fm tuner issue w/ a very popular product.

My Rover buddy has like five of them in his discovery II.

 

[Mrtwooooo]

I noticed the same issue when I plug something into my blue sea USB socket. I get some interference on my ham radio and the car radio. Only when something is plugged into it. I have it powered by a blue sea fuse block. The ground goes to the fuse block and the fuse block is.

I'd like to shield it somehow. Just don't know how

 

[george_tlc]

I've heard of harmonics. just doubtful is all.

i think this is our first report of an fm tuner issue w/ a very popular product.

My Rover buddy has like five of them in his discovery II.

Like I wrote before... EMI can be dependent on many things, wiring is one issue (grounds etc), signal strength of the radio signal (FM, AM, SSB, HAM).

Harmonics of EMI is a real issue, regardless of your doubts. Just bring a small portable FM radio near a switcher (even the bluesea unit) and see how the radio signal gets wiped as you change distance, tuning and antenna length.

What I "DOUBT" is that folk that use the bluesea (and similar) units and have no issues. The issues may not be noticed, folk may not use their FM radio much, or only in large signal areas or just assume the hash they start to hear in weak areas is because of weak signal and haven't tried to power off various noise sources to discover the problem is worse with the noise source on.

In my case I don't care about FM, I stream my own music so if a USB adapter wipes the FM band I'm none the wiser and if you asked me whether the USB adapter was a good one, I'd say yes

Ham folk deal with EMI in vehicles and there's a lot they try, grounding (big fat braid) is one thing, also filters on the noise sources, dedicated wiring right the to battery, shielding, etc etc.

Anyhow, good luck to the folk with the EMI issues.

cheers,
george.

 

[bulldog1402]

To reply to a few questions...


The radio was not removed or harnesses played with by any means.

I am not in a signal strong area, but like I said, it is much weaker than it was previously.

The ground is to the chassis body, not something flakey.

I might try a fuse block wired directly to the battery and see if that helps.