Plagued with noise in radio room, culprit? Battery (Smart) Chargers

I do not do much operating in my radio room in the house, most of my operations are done portable. But for some time now I have been plagued with some major noise to my rigs, the noise is about S9 or more at times and varies on certain frequencies and sometimes with odd sounds.

Not too long ago I had rebuilt my 24v battery pack for my PRC-104 with NiMh batteries, what I had found when the charger was working was the noise was atrocious, once battery was charged the noise would subside but I guess it was never totally gone. So one day when all of our power was down for a tree on the line I tested the radios with battery and found zero noise levels, none what so ever, so it lead me to start searching a bit deeper, looking at TV noise, routers etc, but still no luck nailing the problem.

So I continued to do a bit of more pulling of plugs and seeing what and where the noise could be coming from. I own many types of battery packs and chargers, batteries for radios, cameras and scanners, so I had to start one at a time. I leave the chargers always plugged in ready to go, so never really anticipated that this would be my issue. But I was very surprised when I found two of my chargers that were the problem.

The one charger was indeed my smart charger for my NiMh battery pack for my PRC-104.


The other charger that turned out to be an issue was a Duracell battery charger that I use for my camera batteries. It was amazing at how quiet things got once they were unplugged. The noise on my VX-1700 with these chargers plugged in and not being used would be a solid 9 and more, once I unplugged both of these units the noise dropped to a 3 and I could hear stations once again. I need to look at some of the other chargers in the house that are used for routers and other items in the house.

The NiMH charger when charging makes all bands useless when it is actually charging, the charger for my VX-1210 is the same, very loud noise levels emitted from these units.

So I am glad I did a bit of unplugging and checking and have found some of the issues that have plagued the home shack. Many of today’s electronics is just plain noisy and does emit all kinds of stray RF and noise.

Fred Lesnick, VE3FAL, is a regular contributor to and writes from Thunder Bay Ontario, Canada. Contact him at [email protected].

7 Responses to “Plagued with noise in radio room, culprit? Battery (Smart) Chargers”

  • Francois 3B8GZ:

    Thanks for confirming this issue, how could we reduce or suppress these charger emmissions at source other than un plugging?



  • Mark Booth:

    I have the same problem here in Santa Fe due to Comcast’s router in my house. Constant s-7 noise level on all bands. Drives me nuts!
    How about wrapping the cords of these things with ferrite cores?
    Has to be something besides turning them off.
    And yes, we can find the sources, now what do we do about it?

  • w3fis, Paul Ross:

    Sometimes a ferrite choke in the right place will help. For the really difficult cases, look into other chargers. Some are OK, others not so good.

    What I have found is that a lot of the radiation is from the power cord getting into the house wiring. I have used a VR-500 as a “sniffer” to scout out stuff. Turning of ALL the power in the house and reactivating circuit by circuit, though painful, lets to track things down.

    Good luck!!

    73 /paul W3FIS

    73 /paul W3FIS

  • Bob ce6uff:

    Hi here is the same but the noise comes from cell phone chargers and sat tv decoder ..shure are made in china and without filters .I buy a line filter like a female plug for pc cable and work well but bether is total blackout and battery work on shack hihi

  • Wade/KJ4WS:

    We had some of these same problems at the Shack. Fortunately, everything here runs on 12 Volts. We found that the Astron RS-35M power supply could run these devices just as easily. The Astron has a Big Honking Transformer that operates at 60 Hz. And is Not one of the SMPS or Switched Mode power supplies that cause so much Hash and Trash. We also have two Emergency Back up batteries that come online when the power fails. So now when the power goes out and the TV goes dark. We still have Cable Internet and Wireless. We can still stay in touch and tell exactly what the weather is doing, with the Laptops. All it takes is a bit of creative wiring and you can throw those Noisy Switched Mode, Wall Warts in the drawer. If they aren’t plugged in, they can’t make any noise.

  • Scott W9VHE:

    I have similar problems with cell/USB chargers in my car. Almost completely swamps the broadcast radio. Even when using one of the portable power cells with lithium batteries I get the same thing. The price you pay for convenience.

  • Rick N7WLL:

    Leaving your batteries charging 24/7 shortens the life of the batteries and the charger.

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