It's back, RFI on all bands, including MW

Discussion in 'Interference Problems' started by Kev, Jul 22, 2018.

  1. Kev

    Kev Member

    Greetings everyone,

    Since my last nightmare, I have had this other intermittent noise for some time.

    On all bands including MW, the same nasty old noise.

    I have pretty much ignored it, but recently it's become a problem, so i decided on finding it.

    I knew it had to be something in my neighbours log cabin, which sits at the end of his garden next to mine, every time he leaves the power on at night i get wiped out.

    Today I asked him if we could find it as i was certain it was coming from his cabin, my hand held was telling me so, he agreed and i took my hand held in with me with trusty loop antenna, and immediately saw a perspex led etched name plate hanging to the left of his cabin on the wall, the item was plugged into the mains switched on but also had a on/off switch half way up the cable and a moulded UK plug and the item was in standby mode or off.

    I was using my hand held scanner on 1.930 mhz in "AM" mode, all you could hear was a nasty buzzing when i turned the light on using the switch on the supplied cable, it changed frequency of the buzzing but was even louder, the RF noise covered all frequencies including MW and right up to 50 odd meg's, when it was switched off at the mains it was silent, my neighbour was stunned and I then went into teacher mode to explain it all, i am lucky he was very accommodating about it all.

    I asked if he minded if i could see if i could make it quite using ferrite clamps, and he agreed, so i took it away to the workshop and did some testing, ferrite's made no difference at all, i took the on/off switch apart and found a circuit board with no rf shielding and it was in a plastic case, no CE marks at all on any of it.

    It turns a normal flat signal zero to 9 plus db, a proper jamming device indeed and could be heard on the scanner over 80 foot away, which gave and RF signal of about 3 db at 80 foot, the actual name plate was 3 foot away from the main antenna cable on our 5 way switch. and why it was so devastating being so close.

    I then took away the power switch with its jamming device attached and added a 12 volt cable to it with an on off switch and supplied a 17ah battery.

    All works a treat, Dave my neighbour is happy he can now hang his name plate where he wanted too, as the old mains power cable was very short and restrictive.

    So, it's a result for all.

    Supplied below is some pictures of the actual board with the transformer on it and the plastic case, it came with a power cable, and the led name plate.

    If your going to buy one of these, then please get a 12 volt one and power it from a good power supply that don't cause RFI or power it from a battery.

    Over the moon we got this sorted..

    Happy Days..

    de Kev, 2E0WCK.. 73 [​IMG]



  2. Ken G3SDW

    Ken G3SDW Moderator

    Well done Kev, another load of garbage sorted, ferrite clamp on`s would have sorted it if they were the right grade and had many many turns on them

    Good luck buddy.
    Kev likes this.

Share This Page