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RFI, Losing signal on DAB car stereo

Discussion in 'DIY Help and Advice.' started by Wingchundub, Jan 9, 2018.

  1. Wingchundub

    Wingchundub Member

    Hi all,
    Had this issue a while, but finally got round to investigating.
    Everytime i plug in my double usb socket into cig lighter so i can power dash cam and if needed, phone.
    The dab signal goes.
    This only ever happens when using usb adaptor.
    I have tried ferrites on usb cables to no avail.
    I would like a double usb adaptor if one available that doesn't produces an rf interference, does anyone know of such an item?
    Or is there a modification i can do to adapter that would stop it, obviously apart from slinging it lol.
    Thanks
     
  2. steptoe

    steptoe TK Veteran

    its just the nature of cheap and nasty electronics with little or no RF shielding
    you could try a good quality usb charger, but I wouldnt hold out much hope
     
    Wingchundub likes this.
  3. Wingchundub

    Wingchundub Member

    It is a cheapo jobbie.
    Am currently looking to see if there are any decent usb sockets i can hardwire to cig lighter wires and disconnect cig lighter as not used anyway, bar usb adaptor.
     
  4. steptoe

    steptoe TK Veteran

    you could try putting an extra cig lighter further away from the DAB radio,
     
  5. Wingchundub

    Wingchundub Member

    Last edited: Jan 9, 2018
  6. steptoe

    steptoe TK Veteran

    worth a go at that sort of money,
    wrap it in foil tape that is earthed, might help a bit too,
     
  7. Wingchundub

    Wingchundub Member

    Where it will go is plastic housing, which it clips into, no metal contacts on switch surround or area where switch will be placed.
    If i wrap in foil to earth, i would require an area to attach that earth would i not?
    Confused.com lol
     
  8. steptoe

    steptoe TK Veteran

    the negative terminal on the usb thingie is earth,
    put a couple of wraps of foil tape round it, then a piece of stripped wire and tape more over it to make good contact, take that wire and join it to the negative terminal on the charger, or splice it into the black wire
    its perfectly safe, the whole body of your car is connected to the negative battery terminal,
     
    Wingchundub likes this.
  9. Wingchundub

    Wingchundub Member

    Cheers fella
     
  10. steptoe

    steptoe TK Veteran

    I dont know if it will help much or not tbh,
    but worth a try, it cant do any harm.
    its basically how co-ax works, an outer shield that stops interference entering the signal wire on the inside, youre sort of doing the opposite by trying to stop the interference escaping in the first place

    something like this
    http://cpc.farnell.com/3m/1181/tape-adhesive-copper-19mm/dp/PC01550

    cheaper alternative
    http://cpc.farnell.com/unbranded/foil30/aluminium-foil-tape-30-micron/dp/CBFOIL30

    or you could probably even try some tinfoil, :)
     
    Last edited by a moderator: Jan 16, 2018
    rs500nutter and Wingchundub like this.
  11. Wingchundub

    Wingchundub Member

    I've got some of sticky backed foil on roll, will give it a go and come back once arrived and fitted.
    Much apprecaited
     
    steptoe likes this.
  12. steptoe

    steptoe TK Veteran

    make sure you do a wrap first before attaching your earth wire, the adhesive isnt always conductive, especially with cheaper tapes, so you want to stick your earth to the actual foil side,
    :thumbsup:
     
  13. Wingchundub

    Wingchundub Member

    Update, still waiting for item to arrive, but i changed my mind on product.
    I didn't want to mess with dash, so went for one where i can simply remove original cig lighter, so can wrap it and put away, and put this directly in the dash hole, plus the green lighting roughly matches my original so keep that period look to the car

    https://www.ebay.co.uk/itm/Car-Char...var=552508149208&_trksid=p2057872.m2749.l2649
     
  14. Wingchundub

    Wingchundub Member

    Morning all,
    Part arrived and fitted.
    First install, the led remained on with ignition off, so i wired pos to ignition live and now no power when no ignition, which is what i wanted.
    BUT i still have the issue of rfi.
    What i noticed was, when i connected the socket directly to cig lighter wires, pos and neg, the interference was not there and i was happy.
    Then realising power will be constantly drawn when car not used, i disconnected from cig lighter pos to ignition live and obviously that has solved that, but since this, i now have the annoying interference and dab loses signal.
    So i can say it is definitely something to do with wiring to ignition live.
    I have not wrapped foil of any sort as yet.
    So where do i go from here?Thanks for your guidance, ,much appreciated 20180116_121701.jpg 20180116_135036.jpg
     
    Last edited: Jan 17, 2018 at 8:51 AM
  15. Wingchundub

    Wingchundub Member

    Also realised i already have copper foil, i bought few years back.
    here is what rear of port looks like.
    How do i wrap the copper foil?
    Sorry for repeated question, just also doing house renovation, so loads to do, just want this out of way, so less from the wife lol
    20180117_091008.jpg Screenshot_20180117-091337.jpg
     
  16. Wingchundub

    Wingchundub Member

    UPDATE:- ALL WORKING PERFECTLY

    So what i did do, was get igntion live directly from fusebox for usb adapter and also i decided to do the stereo there aswell after looking up on my fusebox for my olde girl.
    4 points to choose from, so used two of them.
    I was still getting breakup, thou i know now wiring is safer, plus usb shuts power off when ignition off, so a good thing.
    Then i noticed when i move the stereo toward the dash stereo hole back and forth, it would break up, getting closer to other wiring.
    So from the earthing point on A piller of the dab aerial attached to front windscreen, i applied copper tape wrapping cable all the way back to dab aerial port, leaving jsut connector piece which goes into stereo.
    BAM not one blip, crackle or loss of signal.
    Went out today in her for a little 30 min drive and perfect always.
    So was the dab aerial cable that was the issue.
    I did not have to apply additional earth to usb adaptor or cover it at all.
    so for anyone having dab loss of signal, i'd check the cabling as when it is close to other cabling, the interference will occur.
    Wrap in copper tape and jobs a goodun :)
     
    Last edited: Jan 19, 2018 at 3:34 PM
    steptoe likes this.
  17. Wingchundub

    Wingchundub Member

    Even added a ferrite as extra lol 26941890_10215478423661731_906360689_o.jpg
     

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