Radio Static - Page 1
Forum section: electronics / beginners

author: RazzRJB
author_rank: Newbie
timestamp: July 27, 2016, 01:57:58 am
content: Hello,I'm not an electronics person but I'm desperate for an electronics answer!I'm working on my motorcycle. It's a 2012 Harley Davidson Electra Glide, which if you're unfamiliar with motorcycles is a full dresser. That means it has a fairing on the front which houses all the electronics such as the radio, speakers, all the gauges, etc. That's just a little background info. leading up to my question.Here's my problem, I installed a USB port in the lower right hand side of the fairing so I can charge my phone while I'm using the GPS as I sometimes go on very long rides. The problem is that when I plug the phone in to charge it, it completely knocks out my radio. All I get is static unless it's an extremely strong signal. So I thought that OK, I ran the power supply wire down the backbone of the bike which is where the radio antenna wire also runs. That must be causing the problem. I did all this a couple of weeks ago.So today I pulled all that wiring out and re-ran the power supply wire under the bike and back up into the battery compartment completely away from the antenna wire and the result after working out in the 100° Florida sunshine ... the same damn thing!All the connections on the radio are good. All the connections that I've made are good. Everything works fine up until I plug my phone in. One thing I did forget to mention is that I'm using one of the new wireless phone chargers. The mini USB actually plugs into the charging cradle and the phone sits in the cradle. But if I'm not mistaken, I also tried plugging directly into the phone.Can you please tell me what I'm doing wrong or just what I need to do to make it work? I'm really good at fixing things and doing things myself but of course there are some things I simply don't know and apparently this is one of them. Please help me.

author: edp
author_rank: Contributor
timestamp: July 27, 2016, 03:23:18 am
content: You'll need to give us some more detail - how are you providing the USB power? I assume you are using a voltage regulator/dc-dc converter of some sort. Give us more info about exactly what you have & how it's connected.Ground connections on radio etc all checked and confirmed good?

author: VK5RC
author_rank: Unknown
timestamp: July 27, 2016, 03:36:29 am
content: Does the USB charger have a small switch mode power supply ie buck converter? They can be very RF noisy, often transmitting interference directly ie conducted (via power wiring) or radiatively (with some wiring acting as an antenna). A "good" usb adapter may solve it or otherwise a bit of trial with some inductors eg ferrite may help.Good hunting!

author: RazzRJB
author_rank: Newbie
timestamp: July 27, 2016, 06:13:58 am
content: Quote from: edp on July 27, 2016, 03:23:18 amI'm new at this forum page as you can plainly see.All the connections on the radio are good. All the connections that I've made are good. Everything works fine up until I plug my phone in. One thing I did forget to mention is that I'm using one of the new wireless phone chargers. The mini USB actually plugs into the charging cradle and the phone sits in the cradle. But if I'm not mistaken, I also tried plugging directly into the phone. Also, while we're on the subject, I run into the same problem in my truck when I use a USB/cigarette lighter adapter plug, plugged into the cigarette lighter socket or an auxiliary power socket with the same setup, or if I just plug my phone in directly. But, if I use a car charger plugged directly into my phone there's no problems. The same is on my bike, if I plug the phone in using a car charger plugged into the auxiliary outlet in my tour pack, (basically it's a motorcycle trunk) everything works just fine. Perplexing ... for me, I hope not for you.

author: edp
author_rank: Contributor
timestamp: July 27, 2016, 08:01:06 am
content: Bingo.Wireless chargers work by creating an alternating electromagnetic field of reasonable strength, which couples with (basically) a coil inside your phone/battery pack.Radio waves = electromagnetic radiation.It's almost certain the wireless charger is causing the RF interference - but I'm not sure how you could fix it.Others on here will have suggestions (apart from the obvious - don't use wireless charging....).

author: Fulcrum
author_rank: Regular Contributor
timestamp: July 27, 2016, 08:06:56 am
content: Interesting problem!The first thing I would do is to narrow down the possible reasons you're getting static. Bring another radio near your bike and plug in the charger. This new radio will be completely isolated electrically and mechanically from your bike, so if this one also gets static you know it's a radiative problem. If this happens, try plugging the charger in somewhere that is not your bike. For example, have a radio near your laptop and plug the charger in the laptop. Do you still get static? Then the culprit is the charger. also try plugging in the charger to a laptop when your bike is close. It could be that it is the radio in your bike that is very susceptible to electromagnetic interference. My money is on it being radiative problem since it's a wireless charger which emits a lot of electromagnetic radiation (albeit not in the FM band... Usually).If you do not get static on the new radio when it's near the bike, and the bike does not get static when the charger is plugged in near it (but not to it) then the problem lies elsewhere. But we'll cross that bridge when we get there. It could be that the designers messed up when they made the charger. They're not supposed to emit anything in the FM band (about 100MHz), but who knows? It doesn't even have to be in the FM band if your bikes radio is not properly shielded. Is it old?

author: RazzRJB
author_rank: Newbie
timestamp: July 27, 2016, 06:13:38 pm
content: Quote from: Fulcrum on July 27, 2016, 08:06:56 amI'll try everything you mentioned and get back to you, but I wouldn't consider it old. It's a 2012.

author: RazzRJB
author_rank: Newbie
timestamp: July 27, 2016, 06:22:28 pm
content: Quote from: edp on July 27, 2016, 08:01:06 amYeah, that's what I was afraid of. I guess I'll try some other scenarios and see what happens and we'll take it from there.

author: RazzRJB
author_rank: Newbie
timestamp: July 27, 2016, 11:06:47 pm
content: Quote from: RazzRJB on July 27, 2016, 06:22:28 pmWell, when I took the wireless charger out of the equation everything is working ok now. So that leads to my next question, is there anything that can be done so that I can use my wireless chargers? I bought one for my motorcycle and one for my truck. I have quite a few $$$ invested in these chargers I can't use. I hope this isn't a lost cause.

author: Brumby
author_rank: Unknown
timestamp: July 28, 2016, 03:19:47 am
content: Could be a challenge.The radiated EM field will be a function of the interaction between the charging base and the phone/GPS. Both sides will affect what gets radiated.

author: edp
author_rank: Contributor
timestamp: July 28, 2016, 03:35:44 am
content: Put as much distance as possible between the charging cradle & radio/antenna. Yes, your options will be limited as you want it within reach/view on the bike & car dash.Try moving charger around & changing orientation while charging + with radio on to see if there are any changes. Might give you hints for repositioning.Tell us exactly what make/model charger you are using with links/pics if possible.If it's an el-cheapo ebay/aliexpress special it's anyone's guess what it is radiating and you're probably not going to get any help from the vendor.If it's legitimately sold in your country with some sort of official support/backing you at least have some hope. Contact the retailer and ask for assistance. AFAIK electronic devices sold in your country need to meet certain standards limiting EMI. (With a 'legit' product, if the retailer can't fix the problem you could at least try for a refund & spend it on something that makes you happy).Does it interfere with both AM & FM bands?

author: Brumby
author_rank: Unknown
timestamp: July 28, 2016, 04:05:38 am
content: A question to those with the expertise....Would a Mu-metal shield be a possibility?

author: RazzRJB
author_rank: Newbie
timestamp: July 28, 2016, 06:57:17 am
content: Quote from: edp on July 28, 2016, 03:35:44 amOK, right now it's 2:19am so I'll check on some more of the details in the morning/afternoon, or whenever I get up. (I'm retired now so every day is Friday for me) I bought them both from Amazon.com and I've dealt with the one vendor in the past with very good results.Here are the links for both of them.This is the one I'm using in my truck which isn't available from them right now ... or maybe never:https://www.amazon.com/gp/product/B00HHQNPU2/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1And this is the one I'm using on my bike:https://www.amazon.com/gp/product/B018INZ10O/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1I try to stay away from buying things based only on price. I buy the one that I want, or in this case, the one/ones that I thought would meet my needs. However, in this case it seams that I've failed miserably!Unless of course you can figure this out for me.