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AM Radio Interference

Yahoo Message Number: 2381
When I am camping and connected to shore power, I experience interference on any AM radio that is in or near the coach. The radio in the dash works without interference when the coach is going down the highway as do the portable radios. However, as soon as I am connected to shore power, the interference returns. The interference is noticeable on a portable radio when I am outside the coach and close to it. As I walk away from the coach, the interference diminishes. I suspect the problem is the inverter/battery charger.
My coach is equipped with the Heart Freedom 20. Has anyone had a similar problem and if so, how did you solve the problem? I would like to hear local news, weather reports, and traffic reports to prepare for travel.

Dave G.

2000 Allure #30491

Re: AM Radio Interference

Reply #1 –
Yahoo Message Number: 2385
Dave, you are correct. The interference is coming from the Inverter/Charger. I have not found any solution to the problem except tuning to a strong station. Weak stations are impossible.
The damn thing even affects my cell phone in analog mode. jerry in NM.

Re: AM Radio Interference

Reply #2 –
Yahoo Message Number: 2386
Quote from: "
Dave, you are correct. The interference is coming from the > Inverter/Charger. I have not found any solution to the problem > except tuning to a strong station. Weak stations are impossible.
The damn thing even affects my cell phone in analog mode. jerry in

NM.

====================================================================== Isn't there some way that you could "shield" your inverter? or polarize it? I would think that if you put some lead foil around it, that that would eliminate most( if not all) that electrical interference. Where you would get the lead foil I do not know at this time. Maybe, Home depot, or Lowe's, or Wal-mart? These are just guesses......... Hope that my idea helps you.
John

Re: AM Radio Interference

Reply #3 –
Yahoo Message Number: 2387
I'll be interested to see if any of these ideas provide solutions. I also have interference with chargers. Mine are heart EMS 2800s

Re: AM Radio Interference

Reply #4 –
Yahoo Message Number: 2390
Quote
Isn't there some way that you could "shield" your inverter? or > polarize it?

John,

Thanks for the suggestion. However, I am reasonably certain that it will not work. First, the inverter/charger is located in the frame of the coach now. This is a big shield. However, the bigger reason is the interference follows the electrical shore power cable. Using a portable AM radio, I can pick up interference all the way back to the electrical service entrance cable. The closer you are to the electrical service entrance cable the louder the noise interference.
Walk away from the cable or the coach and the interference decreases. This is telling me that it is also feeding back on the shore power cable.

Does anyone have any more suggestions or better yet, a solution to the problem?

Thanks,
Dave G.

Re: AM Radio Interference

Reply #5 –
Yahoo Message Number: 2392
Does anyone have any more suggestions or better yet, a solution to the problem?

Dave, the only thing I've heard of is to get rid of the Heart piece of junk and get another brand (I haven't picked on out yet). I replaced my coach batteries with Lifeline AGMs. The Heart has no current regulation so it overheats when the AGMs are low. When it gets hot enough it turns itself off and on until it finally charges the AGMs. I'm waiting 'til the damn thing fries and I'll replace it with one designed by humans. jerry in NM, '00 Magna.

Re: AM Radio Interference

Reply #6 –
Yahoo Message Number: 2393
A number of technically inclined folks have told me that I should go to a 'true-sine' inverter that would eliminate all related problems with the modified sine waves of the older generation, plus the charging circuits are filtered and up to date to eliminate RF interference. Unfortunately, the tru-sine inverters are quite a bit more expensive. One other benefit to the tru-sine is that you can operate the most sensitive electronic equipment..computers, APC battery backups, etc without any problems. Also, the tru-sine inverters will fully charge batteries just the same as shore power.

Re: AM Radio Interference

Reply #7 –
Yahoo Message Number: 2394
Try this site and you may find some ideas of things to check and resolve the RFI problems.

http://www.arrl.org/tis/info/rfigen.html
Being in ham radion for many years, I have seen my share of RFI problems that was caused by a power distribution systems. If you are getting interference in an AM radio as well as a cell phone, your source has a very wide frequency spectrum. It is likely a radiation or conductor induced interference source. I have seen a simple cleaning of ground points and it cure the RFI. Other times, it is discovered that the RFI is really not being caused by what was originally suspected. The only way to make sure is to isolated one component at a time to troubleshoot.

Once the RFI source is isolated and it is the inverter, you likely will end up removing the inverter and repairing or replacing it. The repair could be something very simple. Think about what causes radiation induce RFI. If you remember as a kid you could take a lantern/flashlight battery and a piece of wire and send Morse code with it by momentarily shorting out the positive and negative poles.
A simple AM receiver would pick up the signal at a good distance.
Think of all the sources inside a inverter that could arc sending out a radiated RFI signal. Something simple as an OFF/ON switch could be the culprit. Or, it could be the plates and windings in a transformer. The contacts of a relay or a failing component on a PC board. It all takes time to discover the exact source.

Even though the website above is geared towards ham radio, the RFI you are experiencing is the same and maybe the website will give you some ideas on possible solution.

Good luck.....

Jim Hughes

Jacksonville, FL
2000 Allure #30511