My two Prosistel rings are just above each set of guys. Because of that, I
cannot let the coax hang below the antenna or use any sort of swing arm below
the antenna/ring.
Instead what I did was to bring the 3 coax lines (from each antenna) up the
short piece of "mast" that also holds the boom truss. Then I allow the coax
to hang about halfway from the top of the "mast," then back up to the tower.
Before final attachment, I had my wife rotate (at the control box) the antenna
a full 360 degrees and back.
YMMV.
Tom, N2SR
On Sunday, November 11, 2018, 10:40:36 AM EST, Grant Saviers
<grants2@pacbell.net> wrote:
A swing arm follower is another way to keep cables away from the tower. I
have 30" long arms about 18" below my Rohn 65 ring rotators to a stub on the
ring and they allow coax and motor leads to follow and not touch tower or ring.
The actual flex point is then at the hinge of the follower, and this works for
the 270+ deg rotation of the seven rings. With a follower mounted just above a
tower top the follower rotation limit would only be the mast diameter so with
some coax slack some over-travel would likely work.
Grant KZ1W
On 11/11/2018 6:13 AM, Joe Subich, W4TV wrote:
>
> On 2018-11-11 8:44 AM, N4ZR wrote:
> > I've never understood typical ham practice of a hanging loop.
>
> Two or three turns laying on the top plate works where one has a
> top plate, the turns are supported so they can't shift and catch
> on a "corner" of the plate, and there is no snow or ice to freeze
> the loops.
>
> Where one has no top plate (a "pointy top" tower, or mast mounted
> rotator) or there is snow/ice, the chance of tearing the cables
> (or cutting the jacket) is much higher in the "two or three turn"
> approach.
>
>>> In broadcast we do it all the time with Heliax on live trucks.
>
> In every live truck I ever built (several hundred), the *entire*
> feedline up the mast was part of the "rotator loop" - that was a
> dozen or more three to four foot diameter turns all the way down
> a 40 to 60 foot mast. It also resulted in the feedline being
> almost twice as long as would have been needed to if it went
> straight up the side of the mast.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2018-11-11 8:44 AM, N4ZR wrote:
>> I've never understood typical ham practice of a hanging loop. What
>> Chuck describes is mechanically much superior.
>>
>> 73, Pete N4ZR
>> Check out the Reverse Beacon Network
>> at <http://reversebeacon.net>, now
>> spotting RTTY activity worldwide.
>> For spots, please use your favorite
>> "retail" DX cluster.
>>
>> On 11/11/2018 8:24 AM, Chuck Tifft via TowerTalk wrote:
>>> No need to transition. I just use about 2 to 3 turns of the LMR in
>>> about a 12" diameter coil basically laying on the top of the tower.
>>> That leaves plenty to absorb 360 degrees of rotation. In broadcast
>>> we do it all the time with Heliax on live trucks.
>>>
>>> Chuck W6RD
>>>
>>>
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