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Latest Topics

Topic Created Posts Views Last Activity
T8 Lamps Sep 20th 2011, 14:56 6 4,230 on 17/6/14
Part 15 and Plasma Televisions Sep 14th 2011, 15:13 2 1,533 on 14/9/11
Common-Mode Interference from Cable System Sep 13th 2011, 15:13 3 1,926 on 25/8/13
RFI from HVAC Systems Sep 1st 2011, 19:08 2 1,506 on 1/9/11
RFI from Plasma TV Sep 1st 2011, 17:20 3 3,868 on 13/9/11
Alignment of Vintage Shortwave Receiver - Pilot T-511 Aug 3rd 2011, 13:43 7 2,914 on 5/2/13

Latest Posts

Topic Author Posted On
Smart Meter RFI on AM Broadcast Band WD4NGG on 24/9/14

I've not heard of this before. I am curious to know if you have been able to listen for it at locations away from your house. Dies it diminish if you listen a few hundred feet away from your home? How about a thousand feet? You could also try tripping the main beaker to your home just before it happens. Listen with a battery portable to see if it goes away. Please let me know what happens.

Thanks & 73,
Mike Gruber, W1MG
Broadband Widespread Interference paulhuffman on 31/7/14
Since BPL does not use the AM broadcast band, the source you describe would not be BPL. Based on your description of the noise, it would most likely be power line noise. Please see the Power Line Noise FAQ page for additional details on this type of problem. Here is the URL:

For a source of local help, your best bet would be to discuss with your ARRL Section Manager. See page 16 of any recent issue of QST for a complete list of Section Managers with contact info.
HF RF Tripping Arc Fault Circuit Interrupters (AFCI's) W4TL on 31/7/14
I can confirm that the troublesome RF susceptible breakers will no longer be manufactured by Eaton. They are now being phased out in favor of the new “Ham Friendly” breaker. After this transition, Eaton does not intend to manufacture both versions of their AFCI breaker.
tvi WD9DMM on 23/8/13

If the problem occurs even when the TV is off, and just the audio is affected, you may have a problem with audio rectification. If this is the case, removing the coax from the TV may not affect the interference. Although this problem is covered in more depth on page 19.9 of the 3rd edition ARRL RFI Book, here are some things that you can try…

First, you don't say anything about the speakers. If they are external to the TV, an easy thing to try is moving the speakers and bundling the wires. Or, if they are internal speakers, you could try disconnecting the wires altogether and plug in a set of headphones. If you notice an improvement, I would suspect audio rectification. It’s a relatively common problem. The RF is being picked up on the speaker wires and being conducted into the TV amplifier. (The output transistors rectify the RF into audio. The amplifier's internal negative feedback circuitry can also conduct it back to the high-gain stages of the amplifier.)

The stock cure for this problem is a common mode choke. The RFI Book has a detailed explanation, but building one is a pretty simple matter. Assuming that you are operating at HF, wrap ten to fifteen turns of speaker wire onto an FT-140-31 ferrite core. You can also use an FT-240-31 core if the speaker wires are large. The chokes should be installed right at the amplifier.

Note: If you can’t get toroid cores with type 31 ferrite, try using type 43. Simply substitute the 43 for the 31 in the core number.

Good luck and hope this helps.
GE X13 AC Air Handler Motor AF4RK on 1/8/13
GE developed the ECM (Electronically Commutated Motor) a number of years ago. It is a brushless high efficiency dc motor now being manufactured by the Regal-Beloit Corporation. They are now being rebranded by the Genteq Company, a division of Regal-Beloit.

For a variety of reasons, they now commonly used in HVAC systems. They can also be a source of RFI to nearby radio receivers. This document published by Regal Beloit also provides information on how to suppress RFI from an ECM motor:

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