Clicks on LF?

Discussion in 'Interference Problems' started by G0CKP, Jan 26, 2019.

  1. G0CKP

    G0CKP New Member

    I wonder if anyone else has experienced S9 clicks on LF? It seems to be worse on 80M, but I can also hear it on 40M.

    The clicks are regularly spaced two seconds apart. I don't think it sounds like VDSL type interference, but I could be wrong. I've had a wander around the neighbourhood using a portable, but I can't seem to pin it down.

    Any ideas, please?

    Steve G0CKP
  2. Ken G3SDW

    Ken G3SDW Moderator

    Before you do anything else Steve turn off your mains supply at the main breaker and monitor on a portable RX.

    That way you will prove that it is not coming from within your own house, if you dont then you may well be chasing your tail.

    If it is still there then do another walk about and keep the antenna on your portable as short as possible to a point of even taking it off completely, that of course is when the signal level is at its strongest, that way you can home into it more accurately.

    Also check with other locals to you to see if they can hear it too.

    Let me know how you get on.
  3. Martin G0HDB

    Martin G0HDB New Member


    If you live in a rural or semi-rural environment then I'd have a wander around the fields in the vicinity of your QTH and see if there are any electric fences nearby. The clicking you describe sounds pretty much like the interference that can be caused when there's a bad joint somewhere along the line of an electric fence - a tiny discontinuity can result in the creation of what is in effect a nice wideband spark transmitter... :)

    The 2-sec repetition rate of the pulses you're hearing is about what I've observed from electric fences in my area - such fences usually seem to be powered from a 12V lead-acid battery so you might find one of those, along with the box that generates the HV pulses, tucked away in the undergrowth somewhere along the line of a fence that is intended to keep livestock from getting onto a public footpath or into a cultivated field.

    Good hunting!

    Martin G0HDB
  4. Ken G3SDW

    Ken G3SDW Moderator

    Yes Martin this is a possibility as from looking at Steves location then it could well be fairly rural.

    In the past with electric fences i have found that when a wire breaks and they often do then the owner just twists them back together and as soon as they get wet then they arc.

    The problem has been to get the owner to replace the wire completely which they seem to be reluctant to do.
  5. M0LEP

    M0LEP New Member

    If the fence is sufficiently high-voltage then it'd only take something like a blade of grass making contact with the live wire (or a fallen twig caught between live and earth wires) to make things click, and that wire makes quite a good RF radiator, too...
  6. Ken G3SDW

    Ken G3SDW Moderator

    If you read what has been said then with clicks evenly spaced at 2 seconds apart then what you have said is most unlikely.
  7. G0CKP

    G0CKP New Member

    Thanks for the advice. The electric fence theory seems like a good one. I've been out several times with my portable, but no luck. I can get signal strength fix of S2 (out of 5), but the clicks seem to be S2 everywhere in the vicinity.

    The searching is hampered because when I walk along the lanes, almost all of the BT line sections emit S5 (out of 5) hash, so I can only get a signal strength reading on a footpath. I've read about VSDL interference in Radcom, but I had no idea the BT lines were so noisy!

    With regard to the clicks, would a frame antenna give sufficient directivity on 80M to help..?

    Steve G0CKP
  8. Ken G3SDW

    Ken G3SDW Moderator

    Yes it would Steve,bit more directional but as for the electric fence then from you first report then if as you say the clicks are evenly spaced "The clicks are regularly spaced two seconds apart." then there is no way it can be a fence.

    Clicks from fences are caused by hi res` joints or greenery brushing up against them,depending on the wind and rain then the clicks will be random not evenly spaced.

    A frame antenna will get you to go in the right direction, as for BT lines well consider what they carry theses days, not only basic phone info but masses of data,hence what appears to be just hash.

    Just caught this one before turning in, good luck and let us know how you get on.
  9. Ken G3SDW

    Ken G3SDW Moderator

    Another point Steve is that in your first post you say clicks of S9, is that on your potable within your house or on your main antenna.

    In your last post you mention clicks of S2, assume you mean walking in close proximity of your house.

    What i am getting at is that if the clicks are strongest in your house, on your portable of course, then the source is very close to home.

    My first post to you said "Before you do anything else Steve turn off your mains supply at the main breaker and monitor on a portable RX"

    Have you done this if so what was the result??
  10. G3YMC

    G3YMC Member

    gm3sek likes this.
  11. Ken G3SDW

    Ken G3SDW Moderator

    Dave i dont profess to be an expert, sorry for that but bow down to your superior knowledge.
  12. G0CKP

    G0CKP New Member

    Yes, I did try turning off the mains in the house, but that made no difference.

    The S2 reading, for the clicks, is on a Tecsun portable receiver. I wasn't getting anywhere on foot (not literally), so I drove to several locations around 0.25 mile away from my QTH instead. I get the same S2 reading at most of those locations, so it's not going to be easy to pin down a noise source like this on 80M, due to the distance the signal can travel. The good news is that I have a SDR receiver and I've found a good combination of AGC, NR and noise blanker to eliminate the clicks!! Many thanks for all the suggestions.

    Steve G0CKP
  13. Ken G3SDW

    Ken G3SDW Moderator

    No problem Steve and thanks for the update.

    From what you have said it covers a large area so as you say be difficult to locate.

    I always tell guys to turn off the mains first of all as this, believe it or not is a most common problem being they generate the RFI them selves, if you do not do it you will be chasing your tail.

    Always here to help at all times.

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