Terrible interference on AM/FM radio

Discussion in 'Motorhome Chat' started by JockandRita, Jun 17, 2014.

  1. JockandRita

    JockandRita Funster Life Member

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    Help please. :Sad:

    Having searched the forums, I couldn't find the answer to the following problem.

    Rita and I are rarely on EHU, and depend on 12v for power, either directly, or indirectly via an inverter. Every time we use either the habitation 12v sockets, (x 2 off leisure batteries) or cab 12v socket, (off starter battery) for charging/powering items, it creates interference when listening to our cab radio, be it AM or FM. Turning on 12v LED lights also causes the problem, (especially the festoon type), but not quite as bad.
    Some times the interference is so bad, we have to either turn the radio off, or play the CD/MP3. Interference is not caused by running the engine, or operating lights, wipers, heater fan, etc, nor from the operation of the Sterling B2B charger, and none of the interference is picked up by a portable radio.

    It has been suggested that we have a bad earth on the habitation side, however, using the cab 12v socket has the same affect. The cab radio aerial is a Bosch amplified window type, and appears to be working fine.

    Is this down to a lack of suppression somewhere, or a bad earth? Whatever the problem, it's becoming a pain in the proverbial.

    Hope someone can help please.

    Thanks in advance,

    Jock (& Rita).
     
  2. ivorantony

    ivorantony Funster

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    Personally I would ditch the window aerial and fit a decent roof aerial with good ground plane,
    If check back on my postings you will see that it took a lot effort for very little gain until I fitted the roof aerial now my reception on DAB/FM/AM is near faultless,
    If your radio worked ok before then a bad earth is the first thing to check,
    Good luck
     
  3. Jaws

    Jaws Funster Life Member

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    With the above

    An awful lot of the better LED bulb units have a regulator circuit on them.
    To say it is poor ( cheap ! ) is an understatement and I have tested some that sling out massive amounts of RF

    Usually the received signal is strong enough to obliterate the 'in house' interference but in your case you have that VERY broadband amplifier that is making matters far worse

    Either a roof or wing mounted proper aerial is really the only decent answer I am afraid, with a decent ground plane ( as in a large area of metal or even tin foil that has a wire running from it to a good earth )

    I appreciate the van you have means it will be difficult but there are ways around it.
     
  4. JockandRita

    JockandRita Funster Life Member

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    Thanks for the replies, Ivor and John respectively.

    I will go back and have a look at your previous postings Ivor.

    The radio has never worked any differently, since we've had the MH, but with a new Sony unit installed, reception and choice of stations is much better. Unfortunately, the interference is still there. There is evidence of a roof aerial having been fitted previously in the front roof shell, but from what I can gather from other Hymer "reception" threads, these were absolute rubbish, hence the Blaupunkt (not Bosch) window aerial fitted by a previous owner.

    Even the well respected audio fitter I bought the Sony unit off in Peterborough, struggled to locate a good mounting point (ground plane) for an external aerial.

    How do I get round it then John. I'm not that keen on drilling holes in my baby. :Sad:

    Cheers,

    Jock.
     
  5. JockandRita

    JockandRita Funster Life Member

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    Bump.

    Jock.
     
  6. Tootles

    Tootles Funster

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    My truck sat-nav plays hell with the radio. So much so we only use it now when stationary.

    You could try fitting a line suppressor to the radio main live feed, you can pick them up from any good car spares shop. Looks like a fuse holder.
     
    Last edited: Jun 24, 2014
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  7. ivorantony

    ivorantony Funster

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    With any reception problems their is no substitute for a good aerial,
    Over a period of a year I fitted two different screen aerials both from reputable manufactures with little effect, then fitted two quality conventional aerials under the bonnet bolted to the chassis, both feeding a splitter to the radio, that gave about a 20% improvement,
    Then took all my radio feeds from the separate leisure battery using shielded cable with inline choke/ suppressor that gave another 10 % improvement,
    Then run a co axel lead from my Status roof aerial to the radio with another improvement of about 20%. at this point I decided to stop messing about!
    In for a penny in for a pound so brought a new Sony DAB/FM/AM/DVD along with a top quality Kinetic DRA-6004 aerial with extra length leads,

    Up on the roof drilled down into the wardrobe fitted the aerial using adhesive back copper tape radiating out from the base of the aerial, one going right down to the bottom of the wardrobe, this was earthed to the chassis,

    I now have a radio fit for purpose:thumb: I have two daughters, one in Scotland and one in Worcester so travel regularly between them, I can now listed to the station I normally listed too almost anywhere in the country,
    My listening habits won't suit everybody but I like
    LBC/ Smooth/Classic/Heart/radio 2/3/4. These nearly without exception are listenable we're ever I have driven so far, I am delighted with the result,
    I used Dabonwheels for the aerial and leads, very quick delivery and good service,
    My motorhome is an A class with a composite construction so if yours has a metal roof it wouldn't need a copper tape ground plane and should perform ok:thumb:
     
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