[TowerTalk] Rotor Loop Question

[Wayne Kline]

Hi Gedas


    I have  in the past with multi antennas on one  mast,   I grouped the coaxes together  ( the most I  had was three coaxes

RG 213 )  I  taped them in a loop and inserted  the  coax in a 1" id HD  tubing/hose  .   This prevented  the edges  from chaffing the coax

in the rotation .

  As for hardline   to coax    I   run them just  below the  rotor shelf  and then group the coax up one leg  into the  hose  cover .


Wayne   W3EA


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From: TowerTalk <towertalk-bounces at contesting.com> on behalf of Gedas <w8bya at mchsi.com>
Sent: Tuesday, November 15, 2016 6:58 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Rotor Loop Question

I am hoping to get a better idea on how to implement my rotor loop for one of my towers. The tower is a 70' aluminum universal that I use for my VHF & UHF antenna in addition to a short rotateable dipole for 40m. The stack consists of: a 17B2 at ~85', a 23 elem 70 cm yagi at ~81', a 5 elem 6m yagi at ~76', and the 40m dipole at ~71'. I am using new Davis BuryFlex (a low loss RG-8 type coax) for all my loops. I have 3 runs of 7/8" heliax going up the tower for 6m, 2m, and 70 cm, and use the BuryFlex for the 40m dipole. All 3 heliax ends currently stop about 1' below the very top of the tower plate. That top plate BTW is a square aluminum plate with sharp edges. I plan to use a sawzall to cut the corners off and file them smooth to help lessen the chances of damage to the coax loops if they touch that plate while rotating the mast.

Today I made my initial connections of the BuryFlex cables to the antennas and roughly taped all of them in place along the booms and down the mast. I have all 4 rotor loops tightly bundled together and held in place with electrical tape every foot or so. I formed the rotor loop with a length of about 5' and have it secured to the mast several inches below the 40m dipole then to the top of the tower about 6" down off the top.

Here is the issue.....that bundle of 4 coaxial cables seems to be so stiff & easy to get twisted up into a mess it just does not seem like it will work well when I raise the tower back up. The tower is currently tilted over via a home-brew mechanism I designed & built and can work on the loop in comfort so I can try different ideas. I am wondering:

1. What is the best length for the loop(s) to be? And what shape should the loop be? I define the loop to be the lowest place on the mast where the cables are taped to the first place the bundle is taped to the tower top.

2. Should I separate the bundle of cables so it is not a single stiff "clump" of cables ? I.e., maybe just let all the coax loops droop freely and not be bound to each other?

3. I am able to change where the ends of the heliax ends up near the tower top....how far off the top should the heliax end to make the best rotor loops?

Appreciate any thoughts and ideas you may have.

Gedas, W8BYA


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