Hello Andy,
you will get the best current distribution (and thus largest radiation
resistance) if you keep the capacitance of the upgoing wire as small as
possible (and the capacitance of the topload a large as possible).
This will be achieved by a single upgoing wire at a as large as possible
distance from the mast and other objects.
Putting a part of the loading coil at the top of the upgoing wire might also
help. You could make a loading coil by winding some wire around the PVC mast
at the top.
73, Rik ON7YD - OR7T
________________________________________
Van: [email protected] [[email protected]]
namens Andy - KU4XR [[email protected]]
Verzonden: woensdag 21 juli 2010 4:52
Aan: 600 meter group; [email protected]; [email protected]
Onderwerp: LF: Best way to connect feedline - advice appreciated
Hello all:
I will soon be finishing my re-construction of my lowFER antenna
to be used at 185 KHz. I will be using a different top hat design
from my previous antenna. I am not sure what would be the best way
to connect the feedline to the top hat, and down to the transmitter.
Photos of the new top hat are at:
http://ku4xr.webs.com/apps/photos/album?albumid=9558802
There are 24 horizontal wires, and 8 diagonal wires ( tensioners )
so 32 wires total in the top hat. The cross arms are 10 feet ( 3.3 m )
in length, and are grey electrical PVC ( UV resistant ).The vertical
pipe for the tensioning wires is 3 feet ( 1 m ).
The mast will be grey PVC, and a wooden " A " frame mounted against
the side of my aluminum sided mobile home,
(I know !! Not Good, but the best I can do)...
The loading coil ( Variometer ) is just inside the window at the
operating position...... Possibilities :::
#1 : A single wire, straight down the mast.
#2 : A single wire offset by about 1 foot, or more ?? to help
lessen the coupling effect.
#3 : Maybe a 2 wire downlead, spaced a given distance apart, and
offset from the mast also at a given distance, then tied together
for a single wire coming into the window at the loading coil.
Any ideas will be appreciated. This antenna will no longer be a
" one man job " it is going to be heavy, and will have to be guyed.
So, once my help is gone, I won't be able to raise, and lower this
antenna by myself like my previous one, so I need to do everything
the best possible while it is on the ground, and hope for the best
when it goes up in the air.
The top hat will be at 36 feet ( 12 m ) AGL, and the APEX will be
at 39 feet ( 13 m ) AGL.
Again, thank you for any suggestions, I'll consider all of them, and
then do the best I can do with the recomendations. Thank you for your
time, and 73 to all :
Andy - KU4XR - EM75xr - Friendsville, TN. USA
LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
*** Temporarily OFF, while constructing a new antenna ***
Coordinates: N: 35º 43' 54" - W: 84º 3' 16"
http://www.myspace.com/beaconxr
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