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Antenna power injector and splitter

Discussion in 'Electronic Basics' started by Captain Dondo, Apr 5, 2007.

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  1. I have a couple of Winegard powered antennas. The power injector has
    developed an intermittent failure, so I took it apart to see what was
    going on.

    It looks like there is an invisible break in the circuit somewhere. I
    could try to fix it, or I could build a new one and address some other


    The injector consists of two RF jacks, one for the TV and one for the

    The power portion of the injector looks really simple. It's a transformer
    with a diode, a cap, and a resistor in series going to the antenna jack.

    There is a 'mystery component' that connects the TV jack to the antenna
    jack. It must be some sort of isolator so that the power doesn't get to
    the antenna. Physically it looks like a tiny 1/2 length 1/8 watt
    resistor. I'm guessing it's a capacitor that would pass the
    RF frequency but not the DC power. It's too tiny to make out any
    lettering or marking.

    Anyone know what value/type this cap would be?

    Second, I have two antennas and two TVs. Right now, I have both antennas
    going to a splitter in reverse, combining the two signals, then through an
    amp, then back to a splitter. (The two antennas in parallel work well
    because of my fairly unique location.)

    There is also a ground block.

    All that makes for a bit of a mess, and I have problems with the splitters
    and signal strength, as the amp I have now is after the ground block and
    the first splitter.

    I'd like to power the antennas and deal with the amplified signal. The
    powered antennas provide 20 dB boost, which overpowers the tuners. I need
    about 6-12 dB boost, so I'd like to have attenuation capability.

    I'd like to eliminate all of that, and build a single box that would allow

    1. Power injection to the antennas
    2. Combine 2 antenna signals
    3. split two TV singals
    4. Provide a ground block
    5. Provide attenuation if necessary.

    I've googled a bit but most of the hits are for wifi and gps, which
    doesn't really apply.....
  2. jasen

    jasen Guest

    dunno about that one, but ceramics are good at RF,
    anything around 10nF should work fine.
    (I see one like that in a different power injector)
    start with a weatherproof alloy box...

    a regular splitter will pass power all ways.

  3. V Sat, 07 Apr 2007 08:31:45 +0000, jasen napsal(a):
    Do you know what's in one of those?

    The only thing I've seen is a guide on how to wrap some wire around one of
    those torroid magnets. It sounds like it would work - but the cheapie
    splitters I see don't have magnets.

    How do they split?
  4. jasen

    jasen Guest

    the two I've looked inside the the centre conductor passing through some
    ferrite bead transfromers and a capacitor from one of the intermediate
    connections to ground, hmm, I guess passing too much current through one of
    these could saturate the core....

    probably what went wrong with the one I injector I built built a couple of
    decades ago (phillips OM350 datasheet)
    poorly I expect.

    Do they have resistors?

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