F****r! QRM (not rude btw)

Thursday I noticed my WPSR results and spot ranking had tanked, I check a receiver and there was an almighty level of QRM, checked the noise charts and spotted that it started at around 8:15 the previous evening (Wednesday).
I rotated the Wellbrook loop but it was already nulling in roughly the right direction so the signal was large. Here is a screen dump from a CB vertical.

As I have been through this many times here I often feel like just giving up and finding another hobby but after a few misserable hours I figured use the S Meter extension and gather evidence.
All through Thursday, Friday and today really bad though different patern to the first day or so.
Checked after running for nearly eight hours today and it had gone off!

By now I had taken the Wellbrook on an extension coax to a number of points so that I could identify it was coming from one particular house (who I have only spoken to once when they moved in).
Despite previous wasted time approaching neighbours about this sort of problem I knocked on the door, they were great.
Turns out it is a cheap battery charger (£18) in a shed being used to charge, and desulphate by pulse, a lead acid vehicle battery.

Don't buy this charger type please, if you see them kill them with fire and bury them at least ten feet deep.

I said I'd try to sort him some filters for tests and lend him another charger but I might just give him my half decent branded one made back when compliance was a thing, can't face this level of junk again.


  • Good catch, and great that the neighbour was willing to interact. That's a win I think.
  • I've Just been looking on Amazon, these are sold under so many brands it is hard to know if any have filter components fitted or if they are all the same, just a bad design.
    I have found one around £25 with detachable AC and DC leads, that would be easier for testing ferrite and/or mains filters.

    Yes I'll take this as a win and even talked to the other neighbour 180 degrees from the actual source about other antenna ideas I though he would object to but didn't, clouds and silver linings and all that.
  • @Powernumpty Interesting finding. Maybe OFCOM would care to issue a sales prohibition? Ours has done so in similar cases.
  • edited October 2020
    Unfortunately I think Ofcom are about as much use as a chocolate teapot.
    I expect the design passes whatever lax regulation it needs to for import approval, then they don't fit the filter components in production for some brands/batches.

    Ofcom's response in the past when I've told them HF is completely wiped out and I know what by was "you need to prove your regular Ham communication was disrupted by this" useless organisation.
    Where modern technology exists that can show, and record disruption to a wide range of frequencies they should be able to do something, hell loan the user a sealed box tested Kiwi and have them run it for a week so that it uploads, or can be polled for a frequency scan every five minutes. Loads of ways they could earn the trust and respect of end users but if the money comes in doing nothing why change?
  • I posted this to the UKQRM group.
    Turns out this specific issue and charger type was mentioned in RadCom (RSGB magazine) a few months back.
    The actual issue is that the manufacturers are leaving off the mains filter components.
    They are still being sold on Amazon.
  • I'm in the US and I have several "NOCO Genius" battery chargers/tenders. These are relatively expensive units advertised as "prosumer". They are absolutely horrific RFI bombs that will completely annihilate HF when they are plugged in. This problem is not just related to dirt cheap no-brand chargers.
  • Out of interest (partly in response to your post) I just tried an Optimate3 charger, could not see any RF at all while charging a lead acid in the same room as the SDR (short test only).
    I think that must be a transformer design as the peak charge current is much lower.
    The Optimate4 (the more recent version) is about three times the cost of those cheapest switchers but I'd happily put some money towards it for that neighbour, if he promises to never use the other types.
  • OFCOM has NO interest in enforcing ANY kind of rules that apply to communications, whether that involves encroachment into Amateur radio spectrum, interference, or nuisance telephone sales and scam calls. A more vivid example of government failure in a body supposed to manage communications issues, you could not find.

    On the issue of terrible Chinese RFI producers and the sale of non-rules compliant chargers, I am guilty of having bought a cheap supposedly intelligent battery charger on ebay. I bought it to keep a motor-cycle battery charged during winter. It emitted horrific interference levels. I could not even hear my VHF FM radio - sounded like a sawmill. I never used it again. I am guessing it would have given problems for a hundred meters all around me.
  • edited November 2020
    Hi Tony, OFCOM and the like are there to give jobs to the boys and to give the appearance of "doing something".
    The only way they work is by comparing the financial value of lobbying, if enough of us push back they may make some small change but I would not be surprised to hear there is a revolving door between OFCOM and the corporations they would have to regulate, and fine, if they actually did their job.

    BTW my resolution -
    I looked at a few chargers and ended up taking a punt on a Ring RSC804 for him.
    My reasoning went roughly "Branded" so bad performance would reflect on other products, leads both coming out one end, so easier for common ferrite clamp if needed and general design. When I got the thing I connected it to a leisure battery and mains while watching the waterfall, I gave it that couple of seconds lag and then looked back at the mains to check it is was on, as nothing (obvious) was to be seen on the waterfall with it charging the same room as the radios.
    That one seems to be OK, I have no idea if he has tried it yet.

    I assume the later Optimates would be good too but they are generally lower current and higher price.
  • Linear chargers rock!

    Excellent catch.... and good on your neighbor to work with you.

  • @dcassell Which NOCO unit do you have and which freqs do you see the RFI? I have one of the newer 5A models and haven't noticed any issues.

  • I just tested a 750W/1500W 12VDC->120VAC inverter and boy is that thing noisy! 😲

  • I shudder to see some of the things sold now. I forcibly get to test a new one very week or two as a close neighbour buys a budget item, kids break it then buy another, worse. The other side gets a new bit of computer kit to review on the same schedule. I've become like a wine taster now - "ah PC PSU, thick odour of Corsair with DC extensions, underlying LED strips and VDSL" - absolutely revolting!

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