HF interference on my ring main?

Discussion in 'Interference Problems' started by M6VWM, Apr 1, 2018.

  1. Ken G3SDW

    Ken G3SDW Moderator

    No problem mate use it either way.
  2. M6VWM

    M6VWM Member

    So glad to report I am far from quitting, I ended up on recommendation of moving on my 857d and getting a Icom 7300, what an amazing radio. The waterfall is really helping figure out the picture of what is happening noise wise and it seems to cope much better with the noise situation.

    My home made inverted L is working an absolute treat, and over the weekend I literally quadrupled my contacts in one day. Even got to Australia and Thailand on wspr on 40m and Oman on ssb. Brilliant experience, I'm back to being hooked.

    The new modem has reduced the noise such that there is always one band that seems to be low noise. 20m often is zero noise in the day, but occasionally goes up.

    Top band has been very noisy, S9+10, effectively unusable most of the time, but I don't really use it so no big loss. 40m is usually about s5 now but has occasional spikes upto s9+ too. Ive had the radio on, watching the waterfall whilst working trying to see the transition. yesterday was a great example 15:49 exactly the noise changed from s5 to S9+10 in moments. At the same time 20m seemed to clear up. Very intriguing. I've also noticed the noise appeared over the weekend when it started raining too. I’ve also watched the streetlights come on and no change.

    After discussions with my club, it has been suggested I get a PME impendence neutral - earth check at the meter.

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  3. Ken G3SDW

    Ken G3SDW Moderator

    Well done Matt, as i have said before today we all suffer to different levels and there are always multiples of locations causing RFI problems.

    It is impossible t try t sort them out all at the same time, only one at a time being the only way.

    The topic of station earthing is top of the most spoke about at the moment, not necessarily the answer but give it a try.

    Dont get to reliant on your waterfall as it will not locate an RFI problem only show you what it looks like in amplitude and frequency, i get moaned at for thinking this way but that is my personal opinion and not adopted by others.

    Keep in touch
  4. M6VWM

    M6VWM Member

    So little update with progress, good news I think. I now have between S3 - S5 noise floor on 20m through to 80m. Top band is sadly still suffering from a gritty frying type noise with about S7. I don't currently use a top band antenna so its no big deal.

    Tracked down 5 different sources of noise with a combination of my AM radio and an RF detector, that have occurred at different times. Im now working with S3 to S5 which is fantastic.

    • My Virgin media modem was very old and causing noise at certain times. After a complaint, virgin replaced it and also reduced my tariff. Win win ;)
    • A battery charger in the garage behind my boundary fence, a slight move of the antenna has removed this rather aggressive interference. This was wiping out parts (equally spaced) of every band from 80m through 20m at S9+ moving reduced this massively so it was barely noticeable and I can only assume the neighbour has stopped using it as its stopped altogether now. I have a similar battery charger at home which is very noisy which is how I deduced what it was.
    • An unused BT phone connection that has been in place since I moved into the house, I am with virgin media. The cable was routed around my house and into an understairs cupboard and had become quite frayed at the outside connection point. The socket and cable was giving off massive noise, ferrites didn't seem to help. I was told that BT would probably charge me to come out and disconnect it as I wasnt a customer, so I decided to just remove the connection into my house entirely. The noise instantly reduced to below S5 at the time.
    • An Apple Macbook Pro charger unit is the worst culprit, when plugged in this is kicking out S9+10 noise. It has made me question if it is a legitimate one but as it came with the machine new it can't be. Ferrites have reduced this massively.
    • The landing light, which is linked to a light in the attic also is causing about S7 noise and static when switched on. Ferrites clipped on haven't really stopped it so I have been ensuring its off when I use the radio and have an electrician coming to check it out soon. I may well get into the attic and add some ferrites onto the cables up there too. It does seem to suggest there is something not quite right with my lighting mains circuit but it is only that one switch that causes it.


      Overall now very happy, as you said it was multiple sources and finding them all has been a real challenge as they appear at different times and with one present it hasnt always been easy to spot that something has gone away.

      The last puzzle is the frying sound on 160m, noise between 7 and 9 but Im sure with time I will figure it out. I have managed to record the sounds with my new 7300 and also screenshot the waterfall. Its fascinating to watch as its clearly a repeating pattern on the screen, almost like a wave moving back and forth. Fascinating.
  5. M6VWM

    M6VWM Member

    sorry I meant the apple charger can't be fake as it came with the laptop new.
  6. Ken G3SDW

    Ken G3SDW Moderator

    Maybe the first move Mat would be to sort out your 160m antenna first.

    One thing that puzzles me is that when all this started you said your turned off your mains supply and the noise was still there now it turns out that most of it was in your own home.
  7. M6VWM

    M6VWM Member

    Most of the time I would turn off the mains and it would still be there, on a few occasions it would indeed vanish. It was why I was so confused and frustrated at the time. Multiple sources as you rightly said all along. With hindsight I think the BT cable was the reason it was still there with the mains was off (assume they are powered externally?).

    I've also have had the whole fuse panel replaced since I first started and I wonder if this has introduced an issue with the light circuit/switch? I've changed all the bulbs, no difference.

    Once the BT cable was removed then it became very easy to find the various internal sources noise.

    The mac charger was the worst but was only a recent discovery as we tend to charge it at night and use it from battery. I was on the radio when my good lady plugged it in and I saw the noise spike to 9+. As you can imagine I asked "what did you just plug in?"

    It's been consistently S3 to S5 on 80, 40m and 20m for several weeks now so fingers crossed. Of course they could be re-radiating as you also said early on. I can operate now and that is fantastic.
  8. Ken G3SDW

    Ken G3SDW Moderator

    In a built up area it is not easy to have a zero noise level as there must be crud of some sort coming from most houses, oddly enough i live in such a place but have extremly low noise, i must not speak to loudly though lol

    As long as you are happy and you can operate then thats fine
  9. M6VWM

    M6VWM Member

    Very happy Ken thanks for all your help, just wanted to let you know I'd made more progress and found a few more sources. Ill keep looking and keep working on keeping it low. :)

    Touch wood your low noise remains too! Sounds wonderful!

    If the EMC team are interested in the battery charger for research let me know I can pass it over.
  10. Ken G3SDW

    Ken G3SDW Moderator

    Thanks for the offer Mat, we have tested many of these and always found the same problem that the mains filter components were missing, left out in production, they had to be in there when it was type tested for it to pass but the crafty little guys in China left them out to save some pennies.
    M6VWM likes this.

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