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Thread: Electrical interference with HF radio

  1. #21
    Patrol Freak BillsGU's Avatar
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    All it takes is a bad connector or a faulty cable and you get all sorts of issues that are very difficult to find unless you have a known working system to swap / compare with. I am surprised there is no one on the Forum that has a similar setup.

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  3. #22
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    Thanks for the thoughts. We are in lockdown for a further four weeks, might get out into a quiet area by December, it can wait. The higher background noise in the range 7.5 - 10Mhz is suggesting something local generating it. Its nothing i can find in the immediate area of the vehicle, and all cables are factory new, well earthed where required and the set has been totally checked and upgraded by a Codan service agent who i have used for 20 yrs. He also serviced the auto tuner when upgrading the radio. Its not the radio, the installation or the earthing. I would have picked overhead power, but ours is underground. There are a lot of wireless connections in the area, but they are way off frequency to the ones getting interference. I am just a bit stumped. The vehicle is in the driveway, 5m from the nearest power, except an inverter a/c unit right next to the car - just thought about that - might be something there, but its a slim chance. If I can't resolve it its going back to the dealer as installed and he can cast his eye over it. I have had a couple of my amateur radio mates look at it also from the club, and they can't fault the installation. Playing around today it is possible to drop the background by 2 pts/5 simply by application of the internal filtering, so maybe its simply a case of detuning it when in the metro areas and amping up the sensitivity when out bush?

  4. #23
    Bitumen Burner DX grunt's Avatar
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    @PeeBee

    I've got a Codan NGT AR HF radio and I have interference problems when I have the UHF CB and the Codan on at the same time. It only happens when I'm moving, not stationary.

    It's like the squelch on the UHF keeps cutting in and out.

    Rossco.
    Winner of 'Best 4 x 4 ' at the 2017 Albany Agricultural Society Inc - Town n Country Ute Muster.

    Ex Telstra - 2005, 4.2 TDi ute -with pod and more fruit than a grocery shop.

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    PeeBee (7th September 2020)

  6. #24
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    Quote Originally Posted by DX grunt View Post
    @PeeBee

    I've got a Codan NGT AR HF radio and I have interference problems when I have the UHF CB and the Codan on at the same time. It only happens when I'm moving, not stationary.

    It's like the squelch on the UHF keeps cutting in and out.

    Rossco.
    Thanks Ross. I an starting to wonder about the a/c unit hanging on my neighbours wall, approx 2m from the radio. I know they are C tick approved, however field effect from inverter drives can be large and under most circumstances not interfere with other devices, but you can bet the requirements dont include the recreational user frequencies which are typically the freq bands that industry can't use effectively. I might back it out into the street a few metres and see what I find. Thanks for the contact. If it does improve, I will move back into the original to confirm degradation, but it would be a really interesting finding, no the least that the neighbour had the a/c unit installed on the wall of here house and it hangs over my boundary, plus is right at the front of the house and is a total eyesore, but she is an old lady and can't take this oversight on board, - will see. The a/c won't be moving and it may simply mean I cant use the set in the driveway, which I dont do in Metro Melb.

    I have the SR NGT, still learning the ropes on it - upgraded from a 9323 as wanted the amateur band flexibility - legally.
    Last edited by PeeBee; 7th September 2020 at 10:09 AM.

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    DX grunt (25th September 2020)

  8. #25
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    Righto, I think I have found the source(s) of the interference. i have my NGT mounted on the cargo barrier, alongside a Victron MPPT solar controller, a Renogy 50amp DCDC charge controller and a 3500W Pure sine wave inverter. The noise floor on 8mhz os 4.5 - 5/5, 6mhz close to this, and everything else from 3 - 14.7mhz lower down to 1 s point.

    I spent a couple of hours removing and letting any charges dissipated from each of these devices and they all contribute to the background noise plane. With everything totally dead, the noise floor is now 2 - 2.5/5, so i put that mystery down as a win. Now it will simply be a case of total isolation of each device, not just an 'off' to start getting some better receive results. My transmissions are fine and strong from vic to Adelaide and tassy, even borderline acceptable for Alice.

    I also might look to physically relocate the HF to a quieter location inside the vehicle, away from this noise.

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