I did search the reflector for a suitable topic to post the this on, but did not find one, so I have started a new one. I hope this is ok.
The increasing problem of man-made interference on the short wave bands is a topic often discussed on the air, online & in the amateur radio press. However, Up until recently I have not experienced anything as severe as I have heard about, other than a relatively high noise level on 6m.
That all changed a couple of weeks ago, I cannot be exact with the date, as I had not powered up my station for several days prior to discovering the problem, but from the time I first heard it, I have kept a log of it. After the first few days when after going off late at night, I was not up early enough to catch its start time, I set up 24 hour monitoring using my computer.
I had of course firstly eliminated anything in my property, & due to limited time, for the first couple of days all I was able to do was take a short walk around nearby properties looking for a somewhere that the noise would peak. I found nothing conclusive as the noise seemed more or less as strong within 3 or 4 properties in any direction from my own.
Whatever the source, the offending equipment generates an S7+, 100Hz buzzing on AM mode,(S7+ mush on SSB) across the entire 80m band for 18 hours a day. On my main station aerial the noise is detectable from 2.225MHz all the way up to 5.700 MHz but is above S6 between 3.0MHz to 4.3MHz. My normal S-meter reading on 80m when the noise is not present would be zero apart from the occasional static crash, hence I originally thought it was very close by.
When I had a little more time I went for a walk & widened my search area, & found the noise detectable on a portable SW receiver up to 300m away from my property, but did find one small area where the noise was much stronger than anywhere else.
Last weekend with a little more time, I tracked down what I believe is the offending property, which is 130m away from mine, but so far have not managed to get any response from the people that live there. So for now, my sincerest apologies, but for the time being, my 80m chasing days are over, unless you happen to activate a summit between 22:30 & 03:45 utc when whatever it is switches off. HI!
I have contacted an RSGB EMC advisor, & what I had already done was exactly the approach they would take, so in the short term I need to continue trying to establish contact with the people at what I believe is the offending property.
Having only once had a complaint several years ago that I was causing “interference” to a neighbours equipment, which was easy to fix with a few ferrite ring chokes on the hi-fi cables & a braid breaker/high pass filter on the TV coax, it is a very different experience knocking on doors some distance away suggesting that their equipment may be causing me problems!
Thankfully, the people I have spoken to so far were very understanding & co-operative, so I must be going about it the right way.
I now fully understand the problems that many amateurs are experiencing with PLT/PLA & similar “QRM generators”.
For anybody interested, here is a 30 second mp3 of what my QRM on 80m sounds like using AM mode. This could be one of several things,but it is certainly something mains powered.
If you have experience of this particular type of noise, that fits with the times I mentioned above, please let me know. Any advice or suggestions will be greatly appreciated.
You can email me at
I understand that EMC issues play a major part in the current UK amateur examinations, but I do wonder…
If the main purpose is tuition along the lines of “How to deal with problems you may cause to your neighbours”, maybe more emphasis should be placed on “How to deal with problems your neighbours may cause to you”.
With apologies to the relevant people if this is already part of the syllabus.
I know of many chasers who suffer from this totally unnecessary man-made QRM from things such as non-compliant electronic & electrical apparatus, so in the absence of a more appropriate topic please post your experiences here. I am certain that any experiences you may have had, especially if you have found a solution to your own problem, will be much appreciated by many amateurs & SWL’s alike.