[TowerTalk] how to do coax on ring rotor?

Wed Mar 27 13:09:13 EDT 2019

I took a bit different approach for my 7 KX0G rings (motor is on the 
rotating ring).  My objective was the coax and motor power cable would 
never touch the tower. I made a 30" long swing arm, mounted below the 
ring, which follows the ring via the cable pull thru its allowed 300+ 
deg rotation.  A 8" fixed arm support is on the ring to further insure 
the cables are well away from the Rohn 65 and ring and to never get an 
"over-center" cable path.  The service loop hangs below both arms. I use 
Buryflex coax and 16/3 for the 180 VDC motors.  There is a small cable 
service loop at the swing arm pivot to accommodate its motion.

This might work with the swing arm above the ring and the cables tied 
out on the boom a bit.  I don't think using the boom guy mast as the 
attach point would meet my goal of cables not touching the tower.

I also fabricated limit switches on the tower with IP65 rated 
microswitches.  Aiming due South isn't of much use here, so the 
sacrifice of a bit of travel is ok.

Grant KZ1W
Redmond, WA

All has worked well and checked out ok when inspected, the last 4 years.

On 3/27/2019 9:23 AM, Dick Green WC1M wrote:
> I have coax and SteppIR control cables, taped together, that loop above the boom because all three of my rings sit about a foot above a guy bracket. The guys and brackets could interfere with a loop below the rings.
> 
> There are some photos of the tower on my website, www.wc1m.com, which shows why below the rings won't work for my setup, but the photos can no longer be enlarged and it's hard to see the loops (and not all that easy to see them in the hi-res versions.) The site is hosted by the ISP I ditched years ago and I haven't done any maintenance since. Need to move the whole thing to a new host. One of the huge number of very time-consuming low-priority projects on my list.
> 
>  From memory (still lots of snow on the ground here), the coax is attached to the tower about 5 feet above the ring, drops straight down and loops back up to the top of the boom truss support, which is a 3-foot piece of galvanized pipe offset from the ring's boom cradle using a custom mounting plate made from roof truss plates. The key is that the boom and pipe are mounted away from the tower face, leaving enough room for a loop. From the top of the truss support, the coax goes straight down the pipe, to which it's taped, then snakes out along the boom to the feed point. Pretty sure I used Bury-Flex for the coax, which is quite flexible, but I might have used RG-213 because the runs from the stack match are only about 35 feet or so.
> 
> 73, Dick WC1M
> 
> -----Original Message-----
> From: Tim Duffy <k3lr at k3lr.com>
> Sent: Sunday, March 24, 2019 3:26 PM
> To: 'StellarCAT' <rxdesign at ssvecnet.com>; 'tower' <towertalk at contesting.com>
> Subject: Re: [TowerTalk] how to do coax on ring rotor?
> 
> HI Gary
> 
> Have the loop below the boom works very well here. You have to have a safe climber in place for the installation and it check out  360 degrees while someone in the shack (linked by radios) operates the control box. Take measures to insure the coax can never get caught by the guy attachment hardware. The key to this is coming off the boom about 3 feet away from the tower face.
> 
> 73
> Tim K3LR
> 
> 
> 
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of StellarCAT
> Sent: Sunday, March 24, 2019 1:56 PM
> To: Tim Duffy; 'tower'
> Subject: Re: [TowerTalk] how to do coax on ring rotor?
> 
> Thanks Tim ... as I wrote David direct -  it was a "DUH!" moment when I read his note - which was to use the truss support upright. I have been focusing too much on the actual antenna and the coax along the boom .... thinking loops around the tower and drapes etc.... I hadn't even considered the truss support. That should be pretty straight forward.
> 
> I do have a guy right below, within 3', so I'm reluctant to let it hang down directly from the boom .... although it looks like that is what you do Tim.
> 
> 
> Gary
> K9RX
> 
> 
> -----Original Message-----
> From: Tim Duffy
> Sent: Sunday, March 24, 2019 12:27 PM
> To: 'StellarCAT' ; 'tower'
> Subject: RE: [TowerTalk] how to do coax on ring rotor?
> 
> Hello Gary:
> 
> You can go to my website and see lots of photos of coax with ring rotors.
> There are 23 ring rotors here - so if you have questions after looking at
> the photos and videos - please email me and I will help
> 
> http://www.k3lr.com  look at contest photos and videos
> 
> 73
> Tim K3LR
> 
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> StellarCAT
> Sent: Sunday, March 24, 2019 12:00 PM
> To: tower
> Subject: [TowerTalk] how to do coax on ring rotor?
> 
> I’ve got two TIC ring rotors that are going up – hopefully this spring ...
> they’ll have 2 7 element 10’s on them ... (yeah, I know, 10M’s).... and I’m
> trying to figure out the best way to handle the coax coming off of the
> antennas. Both going up from the ring as well as going down. I need up
> because one of the rings will be mounted 4’ above a guy point so going down
> isn’t likely to be a solution.
> 
> Anyone done this already and gone through the trials and tribulations of
> getting it right?
> 
> You’re welcome to write direct to my ARRL email address or post here...
> 
> thanks – Gary, K9RX
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