[AMRadio] Antennas


Rob Atkinson ranchorobbo at gmail.com
Mon Jun 21 14:33:41 EDT 2010


One of the challenges of AM is that because the power is spread
amongst carrier and two sidebands the power transfer from the rig to
the sky has to be maximized in order to have quality QSOs as opposed
to "Sorry OM dinner bell, gotta go."

Ur Carolina Windom is too low, especially at the ends where  you are
loosing a lot of power to ground due to coupling.  It may seem to be
okay because if condx are good and/or you are operating cw or ssb you
may be told you are "booming in" by a polite operator but if at that
moment you could do an a/b with the antenna Bernie recommends I
guarantee you'd probably gain 10 dB.   Those C.W. antennas use baluns
(another power waster) so you will be far better off with a 1/2 wave
75 m. dipole fed in the center with open wire feed and a Johnson KW
matchbox or some other link coupled tuner, i.e. the antenna Bernie
described.   Get it up at least 50 feet and you will be amazed.
Don't get me wrong, it won't be a 75 meter dx antenna; it will still
be a cloud burner but the loss to ground will be way lower and with
100 to 200 watts carrier you will have a pretty strapping signal
unless condx are really bad (like they have been lately).
If you can go higher that's even better.

73

Rob
K5UJ

On Mon, Jun 21, 2010 at 7:56 AM, Brian - KF5CCN <bzwiener at sbcglobal.net> wrote:
> I have a Carolina Windom Dipole I use on AM and SSB, oriented with ends N/S at about a 30 deg. downward slope and ends 4 ft. above ground. I get good reception and coverage all around the compass. But on AM I seem to be week on AM toward Dallas and Oklahoma. I "boom in" on 75 meters in Dallas, OK, LA, MS, and other states.
> Is there a particular antenna and/or antenna configuration that is more effective on AM? I know RF is RF, but, I am still learning.
>
> Thanks and 73
> Brian/KF5CCN
>
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