Advice on cancelling locally generated noise

An SWLing Post reader recently contacted me with the following question:

“What devices work well to cancel out local RFI? I’ve been told that both the Timewave ANC-4 and a number of BHI products are all worth considering.”

Unfortunately (or fortunately, for me) I’ve no experience with outboard DSP or noise cancelling devices because I live in such an RFI-free area.

I know this reader already has a Wellbrook Loop, but he’s looking for a way to even increase noise mitigation further at his home listening post.

Post Readers: Can you help guide him?  Please comment with your experience. Is a product like the Timewave or BHI the next logical step? If not, what is?

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10 thoughts on “Advice on cancelling locally generated noise

  1. John Mosman

    I live in a packed neighborhood with a power line and cable line across the back property line ( about 100ft. from the house)). I have a coax antenna from the house running towards the back line (perpendicular to the power/cable lines). We are twenty miles from O’Hare Airport. The house is the usual packed home with four cable boxes and assorted other electronic devices. Did I say very noisy?

    I have an Icom R75 and honestly, I am not very electronics savvy. Would adding a MFJ-1026 provide enough relief to at least listen to the SW bands again?

    Thanks, John

    Reply
  2. Cap

    I do believe the go to unit is a MFJ-1026 noise cancelling unit.
    Never tried it but heard others swear by it.

    Cap

    Reply
  3. Sean Gilbert

    Some noises are very difficult to remove – VDSL and PLT, for instance. I use a Wellbrook loop together with a modified MFJ-1026 and a 21m long OCFD. Most of the time I can remove unwanted signals but it does not touch the VDSL (not mine, I hasten to add). I’ve tried all kinds of sense antennas over the past 4 years to remove it but to no avail. I’ve made my house as quiet as I can with mains filtering and ferrite chokes on every possible lead. I have a new antenna to put up (a Cross Country Wireless active loop), which I hope will make a positive difference when used with the MFJ-1026 and ALA1530. When the noise source is not in your own home, it is very difficult to sort (particularly in the UK, as OFCOM are not really interested any more). The BHI solution will help with audio noise but will not do anything to remove unwanted signals. I use an audio DSP (like the BHI) on the audio outputs of my radios and it does help to clean up speech and peak CW signals. See if you can locate the source of the noise and, if you can, see if anything can be done about it. The RF smog that affects our hobby so negatively is increasing exponentially and we need to be ever more creative to find ways to continue enjoying it.

    Reply
  4. DL4NO

    The most important consideration: Where does the noise come from? Are you sure it comes from what you consider to be your antenna?

    Quite often your antenna is MUCH larger than you think. A typical case are next to all “end-fed” antennas: The antenna needs some current that must come from somewhere. Quite often this “somewhere” is your whole electricity wiring. Examples:

    * Telescopic antenna – radio set – power supply – mains
    * “End-fed” antenna – balun – antenna mast – mast grounding – mains

    Easy ways out are symmetric antennas or magnetic antennas.

    Reply
  5. Andy

    The noise around here is terrible, especially on the low bands (LW, MW and low HF) so years ago I got a Wellbrook loop. It’s brilliant, taking the noise level from a typical s8 to s1. There are still some strong switch-mode power supply noises that won’t null right down, so for these I use a homebrew canceller, which uses a small ‘short wire’ noise aerial to pick up the local noise. The canceller takes the noise, inverts it and adds it to the signal+noise from the main antenna. This can help get the stubborn noises almost down to nothing. The only problem with cancellers is that really they can only deal with one noise at a time, and sometimes as you cancel one noise, another noise from another direction comes up!

    Reply
  6. Ross

    I endorse Bill the Cats suggestion, Hi Hi I live in an RFI free rural area however my standalone solar power supply inverters generate some RFI. By running my station off the property battery supply ….in my case either 12/24 or 48 volts i have a very clean RFI environment.
    Secondly I have several BHI products and they are excellent performers and will make a difference to your reception.
    I have some very sophisticated transceivers with IF DSP and multiple noise/filter aids but find the BHI A/F DSP units will improve a difficult signal in the noise on them as well.
    My suggestion would be to purchase one of the BHI filter units without speaker such as the NEIM1031 Mk2 amplified DSP module and use a good comms or middle channel 5-1 sound system speaker if you can’t afford the larger desktop type 10 watt BHI speaker.
    The smaller mobile style BHI DSP speaker with mobile bracket is a bit inadequate sound wise and not as good as the DSP module it is paired with IMHO for desktop use.
    I have fitted BHI modules into comms speakers and have the smaller DSP mobile speaker unit in a vehicle but my favorite if just wanting a plug in is the NEIM1031Mk2 with an outboard bookshelf speaker.
    regards Ross.
    You will notice a difference.

    Reply
  7. Chris

    I actually own both a Timewave ANC-4 and a bhi dsp desktop speaker and I am a SWL as opposed to utility or SSB. The Timewave is great- once you get a noise antenna set-up to match your conditions. The bhi desktop with 8 levels of filtering is one of the greatest pieces of equipment in my shack, next to my Wellbrook LNP loop. I recommend both pieces of equipment.

    Reply

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