Identifying QRM on 70 CMS

Discussion in 'Interference Problems' started by G6SPG, Oct 6, 2018.

  1. G6SPG

    G6SPG New Member

    Hello Everybody,
    I have recently started to experience local interference on 70 cms.
    It is in the form of a pulsating carrier, which i possibly believe to be eminating from a house at the rear of my property. The signal is about 100kc wide and centres around the FM calling channel 433.500

    I have placed a video on Youtube with the hope that someone has also experienced the same kind of qrm



    I would appreciate any help in this matter

    73 de G6SPG

    Paul
  2. Ken G3SDW

    Ken G3SDW Moderator

    Hi Paul, i would not call it pulsing but just bursts of something local to you, vicious and quite strong.

    With just the odd burst then it is impossible to say what it might be but what ever that maybe is not important, more to the point is were is it coming from.

    You say that it may be coming from a house at the rear of your property, why do you think that this maybe the case??

    To make 100% sure that it is outside your property then you must turn off your own mains supply at the main breaker and monitor on a hand held RX, if not then you will be chasing your tail and go round in circles.

    Let us know how you get on as i am always here to help.
  3. G6SPG

    G6SPG New Member

    Hi Ken,

    thanks for the reply, sorry I should have already mentioned the fact I have already took my property out of the equation, basically it was the first thing that I did.
    Have monitored both walking with a handheld and also mobile and the signal does tend to peak at a certain section of the road at the rear of my property.

    The power level is probably only milliwatts ? Have also had a fellow Amateur monitoring the frequency who has a house located near the end of this particular but not able to pick it up.

    Regards

    Paul
  4. Ken G3SDW

    Ken G3SDW Moderator

    Well then you need to confirm as much as you can that it is the suspected house and then knock on the door and in no way accuse just ask for there help in trying to locate the problem, even letting them hear it for them selves.

    They may well assume you are talking about CB so try to explain that you are licensed by Ofcom to operate your radio equipment, in may cases when radio is mentioned then there is an assumption that it is CB.

    Let us know how you get on and i know that knocking on doors is not what we want to do but until you do it will not go away, whoever it is will not have a clue that they are causing a problem so i am sure they will listen and help all they can.
  5. Ken G3SDW

    Ken G3SDW Moderator

    Hi Paul, just wondering what the latest is on your noise problem.
  6. G6SPG

    G6SPG New Member

    Hi Ken,

    Sorry for the delay in replying, I'm afraid the QRM problem has had to be but on the back burner for a while.
    I have been away from home and pre occupied with some serious family matters.

    I will keep you updated when i get nearer to resolving the problem.

    73 Paul
  7. Ken G3SDW

    Ken G3SDW Moderator

    OK Paul stay strong.
  8. vu2nan

    vu2nan New Member

    Hi OM Paul,

    The 432 MHz band is a shared one with Radio Amateurs having secondary status!

    73,

    Nandu.
    Ken G3SDW likes this.
  9. Ken G3SDW

    Ken G3SDW Moderator

    Nandu, we are fully aware of this in the UK and his problem is nothing to do with anything shared locally to him.
    Last edited: Nov 13, 2018
  10. vu2nan

    vu2nan New Member

    Thank you for the information, OM Ken.

    73,

    Nandu.
  11. Ken G3SDW

    Ken G3SDW Moderator

    73 from the UK

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