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
________________________________
From: TowerTalk <towertalk-bounces@contesting.com> on behalf of Gedas
<w8bya@mchsi.com>
Sent: Tuesday, November 15, 2016 6:58 PM
To: towertalk@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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