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How to get power to my aerial amplifier

Discussion in 'Electronics' started by nigelcorby, Jan 11, 2016.

  1. nigelcorby

    nigelcorby New Member

    Jan 11, 2016
    Mercedes ML320 CDi
    I have a 2006 ML320CDi with an Audio 20 head unit and CD changer. No bluetooth or aux input.
    On the back it has two coax connectors for the aerial(s) one black and one mustard yellow colour.

    I've fitted a replacement head unit from Kenwood which obviously has a standard aerial connector and I used a single Fakra to Din adapter.
    All works fine except I get a very weak FM signal.
    This leads me to suspect I'm not getting power to the aerial amp any longer so my question is how do I do that now that I'm using a non standard head unit?

    So far I've learned from another forum that the yellow Fakra is probably for a diversity aerial connection on my particular model/year of car.

    I did a little test and removed the mustard coloured coax connector with the original head unit attached and got similar results (very weak aerial signal). so this leads me to suspect that that cable has phantom power on it for the amplifier.
    Anyone know if this is correct or is the power supplied by a separate wire on the main connector? If so which one?

    I have a limited time to solve this before going on a lengthy trip so any input would be most welcome

  2. markmifsud

    markmifsud Hardcore MB Enthusiast

    Nov 17, 2008
    Bromley, London
    CLK320 CAB (A208) 02
    you need to look at the original H/U and look for a connection coming out from the unit that powers up to 12v when the radio is powered up, as opposed to becoming live feeding the radio. Once you have located that, then you have the correct wire that needs to be fed 12v from your Kenwood to power the active antenna.

    A quick google suggests it could be connector block 2 (block 1 is the speaker connections) pin 3

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