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Re: [TowerTalk] 90 degree coax bend atop a crankup tower

To: towertalk <towertalk@contesting.com>
Subject: Re: [TowerTalk] 90 degree coax bend atop a crankup tower
From: Robert Harmon <k6uj@pacbell.net>
Date: Thu, 4 Jun 2015 09:17:32 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Peter,

I agree with Dave.  Heres what I use:  a 2" long radius (1 1/2" will work too 
for just a few cables) pvc 90 degree elbow, cut into into two pieces long ways 
along the sides, (I cut the bell end off first )use the piece open at the top 
like a trough, attach to the top with SS screws and you are good to go.  Easy 
to cut and cheap and holds the cables 
nicely.  Did I mention that it is cheap ?    hihihi 

http://www.homedepot.com/p/Carlon-2-in-90-Degree-Sch-40-PVC-Elbow-UA9AJB-CAR/202304075

73,
Bob
K6UJ






> On Jun 4, 2015, at 8:16 AM, David Robbins <k1ttt@verizon.net> wrote:
> 
> a sweep with a 6-12" radius would be much better than hanging over an edge 
> like that.  also think about adding a guy wire to the bundle to support the 
> weight instead of letting it be held by the cables.  The guy wire would also 
> be useful to limit swinging in the wind to prevent flexing at the bottom if 
> the cables blow around.
> 
> 
> Jun 4, 2015 11:10:11 AM, contesting@w2irt.net wrote:
> 
> Hello all,
> I’m using an old LM-470 crankup tower and have a question about best
> practices in cable routing. At the moment I don’t have my coax feeds bonded
> to the top of the tower. Feeds from all four antennas, after forming the
> rotor loop, are taped securely to a cable arm. They make a sharp 90° bend
> and then dangle by gravity through two more cable arms in their run to the
> antenna switchbox mounted at the base of the tower. That 90 degree bend
> cannot be good for the bundle of cables. It’s high-quality stuff that’s been
> up there for 9 hot summers and 10 freezing winters now, and I’m thinking of
> replacing it either this year or next, as money allows.
> 
> This picture shows how the cables are routed at present.
> https://db.tt/Hd3R7rrI.
> 
> 
> 
> Is there a preferred method of routing cables that doesn’t involve a sharp
> bend like that? I’m imagining there’s quite a nasty impedance bump going on
> here, not to mention the potential for physical damage to the dielectric in
> the heat and cold, etc. If I’m going to spend hundreds of dollars in new
> feedline, plus the costs of having it installed (I cannot climb, myself), I
> want to ensure it’s done to best engineering practices this time. I also
> think having the lines bonded at the top of the tower would be a Good Thing,
> as well, so maybe a way to incorporate that and a new sweep or something to
> get the cables headed downwards more gently?
> 
> Thanks in advance. 
> 
> 
> ---------------------------------------------
> GO FRC!
> Peter, W2IRT
> 
> 
> www.facebook.com/W2IRT
> 
> 
> 
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