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Re: Feed line routings



Alan,

at the Delfi-C3 groundstation we used to follow the "loose school" 
approach, but since our permanent ground station is at 85m ASL it 
suffers from a high wind load, thereby swinging the antenna cables back 
and forth. So at our last antenna upgrade we went for the "tight school" 
approach, whereby the feedline leaves the cross mast about half way to 
the back of the antennas, thereby not having the feedlines parallel to 
the boom which could distort the antenna pattern. The groundstation is 
in more or less continuous unattended operation, so secure cable routing 
is a must here.

Pictures of this can be found at the following url:

http://www.delfic3.nl/forum/showthread.php?t=386

and

http://www.delfic3.nl/forum/attachment.php?attachmentid=1033&d=1147000524


For the feedline around the rotator we use aircell7, combined with RG-58 
for carrying 12VDC to the polarization switching relays.

73

Wouter Jan Ubbels PE4WJ
Delfi-C3 project
www.delfic3.nl
>
> Message: 2
> Date: Sun, 14 May 2006 21:45:08 -0000
> From: "Alan P. Biddle" <APBIDDLE@mailaps.org>
> Subject: [amsat-bb] Feed line routings?
>
> Howdy,
>
> I have been wondering about the best, or at least the most common, way to
> route feed lines to a typical AZ-EL system.  One school, the "tight school,"
> routes the cables directly along the support, around the rotators, down the
> cross mast, and then out to the antennas, with or without supports except
> for strain relief.  The "loose school" goes from some point on the support
> below the rotators directly out to the antennas, with some strain relief.
> My impression from various pictures in The Amsat Journal and QST is that the
> first is more common with relatively permanent stations, and the latter with
> Field Day, DXpedition, HOA-mandated low profile, or other similar temporary
> systems.  The first has the drawback of flexing and chafing over smaller
> turn radii, and the second a lot more motion due to winds, and more chances
> to catch on something.  By the time you have antennas for modes V, U, L, and
> S, plus the preamp power and circularity switching some require, it gets
> rather crowded if you do it "tightly," and lots of relatively free cables
> flapping around if you do it "loosely."
>
> I am in the process of refurbishing my somewhat congested roof tower system,
> which just sort of grew that way over 20 years.  Does anybody had any strong
> thoughts on this?  Hey, it's a slow Sunday afternoon, and I have to finish
> my shopping list for Dayton.  ;)
>
>
> Alan
> WA4SCA
> - ----
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