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Radio Antennae

Discussion in 'Beginner Electronics' started by Mathussic, Aug 11, 2006.

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  1. Mathussic

    Mathussic Guest

    I have a clock radio that uses the electrical plug as the antennae.
    However, the reception in my bedroom is really bad during the summer
    months, but gets somewhat better in the winter months.

    Anyway, is there some type of connector plug that I can plug the radio
    in to get better reception?

    Any help appreciated,
    Chris
     
  2. default

    default Guest

    AM or FM, what frequency? Is there a connection on it for the
    antenna? Two or three wire cord?

    (some line cord antennas are a piece of steel crimped on the
    insulation of the power cord and attach to a screw on the back of the
    radio - you remove that and add a wire or dipole antenna to the screw)

    Are you able to have an external antenna where you live? Is it only
    some distant stations that give you problems?
     
  3. default

    default Guest

    Draping the wire around to improve the reception implies an FM VHF
    frequecy - should I assume that?

    With AM frequencies a large tuned loop antenna in close proximity to
    the internal ferrite antenna can dramatically improve reception.
    The external things - design and build a pre-tuner to capture the
    signal from a real antenna and then capacitively couple it into the
    power line with a "gimick" cap like some aluminum foil wraped around a
    portion of the cord.
    Locate the RF input and bring it to the outside of the case so you can
    add an antenna - probably want to disconnect the power cord antenna
    too - and take pains to make sure the installation is shock proof,
    since the chassis/common may not be isolated from the power line.
    Takes some knowledge to pull it off - ideally one wants a balanced
    input if it is VHF.
    There may not be much you can do about that without opening the case
    and adding an antenna - typically they receive one or more of the
    standard time broadcasts in the HF range - the building is probably
    inhibiting the signal. shock isn't an issue with battery power so
    that may be a good option - also check out the instructions, they may
    already have a solution.
     
  4. default

    default Guest

    On Fri, 11 Aug 2006 13:10:41 GMT, "Steve Saunders"

    I made one other assumption - that the radio is working properly. A
    power line spike caused by lightening may have wiped out the first
    amplification stage. Has the problem always been present?

    Will it work properly in a wood frame building?

    How far away is(are) the station(s) and what is in the way? VHF and
    high frequencies are line-of-sight. 20-30 miles may be all as good as
    it gets with no proper antenna - with a good antenna in a good
    location that same signal could be good for 100+ miles.

    Put it on a ground floor surrounded by tall buildings, hills, or other
    obstructions and you will need an antenna mounted where it can catch
    some of the signal.

    Not a concern with AM radio as a rule.

    It is likely a location problem - type of building or surroundings are
    attenuating the signal too much.
     
  5. Guest

    Not directly, really.

    Best bet is to crack open the radio, find out the antenna lead and then connect
    the antenna to that. (I'm guessing it'll be a wire wrapped around the power
    chord some place inside the radio, it's quite doubtful to me anyhow.. that
    they'll connect straight to the AC line)

    Chances are, if you do that, it'll only inprove FM reception. I've never heard
    of such a device used as the AM antenna.

    For "improved" AM reception (improved in quotes, because this may and probably
    will actually worsen it..)

    I've wrapped wire around the ferrite rod, grounded one end and then use the other end
    of the wire as an antenna. Theory being.. find a way to inject a signal into
    the ferrite.

    In practice: Improved reception at the cost of having some strange tuning,
    hearing strong shortwave stations all across the dial. Fortunately, this can
    easily be undone if it's a problem (and you're careful with the wires)

    These are cheap tricks I've used in other various places.. of course.. the best
    bet is to find a "real" radio. :) (I'd imagine if they did the antenna-via-powerline
    approach, they probably designed the radio circuitry as cheap as possible)

    Jamie
     
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