At 14:10 9/11/98 -0400, you wrote:
>
>All antennas that are non-symmetrical or non-symmetrically installed with
>respect to the environment around them, and less than perfectly grounded at
>the feedpoint, have this problem to a greater or lesser extent. Even if the
>feedline isn't conducting noise from the shack to the antenna, it may be
>contributing unwanted signals and sky-wave or ground wave propagated noise
>that deteriorates directivity.
>
>The Pennant.............
Tom,
I agree with your statements, but I'm not all that comfortable with the
theory behind the observations yet. Rather than clutter up the reflector
with theory at this time, lets just all agree that it is imperative that
most, if not all, RX antennas have extreme common mode feedline isolation.
Maybe we can take up the theory part of the discussion when we/I have more
emperical data.
Hindsight is always 20/20, and I think I now know why some of my RX
antennas at other QTH's have not preformed as well as I thought they
should. I should have tumbled onto this problem years ago and feel kinda
foolish now. Oh well!
The Amidon catalog does not seem to have a 73 material binocular core of
the dimensions that you used. Do you have a part number and/or vendor for
the cores you like? I may just glue two shorter core together if I can't
buy them that length. I've done that in the past for solid state amps and
it seems to work OK in that application.
73,
Larry - W7IUV
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|