Steve,
You have a complicated situation here. Let me try to simplify it.
First, the antenna at the top:
I use a HiGain HG-52SS crankup and use coax arms to stand the coax off the
tower on the way up the tower to the mast. I leave a loop of coax at the top
of the tower to wrap around the mast (enough so that the mast has more than
360 DEG rotation capability). Ok, even with two coaxes doing this, it should
be Ok. I actually have two antennas on my mast with two coaxes...similar to
your arrangement. If you must use the switchbox (it is another point of
failure, but lowers the cost of coax. I'd say use two full runs of coax),
mount it at the tower base and switch there.
Ok, now for the ring rotor:
The coax needs to come up from below the ring rotor and droop down then up to
the antenna (I know, two feedlines. Both need to do this.) See my photos of
several ring rotor installations on my big tower at
http://www.erols.com/n3rr).
So, how do you do this on a crankup tower? I'd suggest that you use coax arms
at every tower section (mentioned above) including one that is attached to
the top of the section just below the ringrotor mounting plate (I'm assuming
you are using the standard TIC crankup tower insert like that shown on my
commercial site: http://www.erols.com/n3rr/n3ringrotor/index.htm).
That being the case, starting at the tower base: the coax bundle (which
contains four coaxes: two for the top antenna and two for the antenna mounted
on the ring rotor) attaches first to the coax arm on the fixed tower section,
droops about 2 ft, then goes upward to the first coax arm (no ring rotor
yet), droops about 2 ft, then goes upward to the next coax arm (no ring rotor
yet), droops two ft, THEN slopes gently upward to a point UNDER and INSIDE
the ring and RIGIDLY attaches to the coax arm that is under the ringrotor.
Then the coax is attached to the full length of the coax arm (instead of
going up to the next coax arm) and through the ring and attached to the tower
section with the ringrotor.
Then: 1) the two coaxes to the top beam go through the ring with little or no
droop and up to the coax arm at the top of the tower to the antenna at the
top. The angle to the top coax arm need sto be adjusted to allow the
ring/antenna to rotate without getting close to this coax bundle (two
coaxes); and 2) the two coaxes to the antenna on the ringrotor go down the
tower (back through the ring) (remember, these have been rigidly attached to
the tower at the coax arm at the ringrotor) to a rotation loop of, say, 4
feet (for 24 inch face towers) then up to the feedpoints on the antenna. The
rotation loop for the antenna on the ring should be 4 ft down and 4 ft up and
be able to miss the tower as the tower is lowered. This is adjusted by
attaching the coax to the antenna boom at the correct point.
Further, both coax pairs ought to be taped together in pairs every few feet
all the way up and especially at the various rotation loops.
Whewww...does that make sense? I am visuallizing as I am typing and I think
I stated it correctly. If your tower has fewer or more sections than I
assumed above, modify my text accordingly. I troed calling you just a few
minutes ago, but RNA (ring-no-answer).
I copied this to the list because we at TIC ( I am an authorized independent
representative) are promoting the concept of ring rotors on crankups,
especially since the sunspots are back and lower antennas (add a 10M beam to
your crankup) wil work better now.
Questions anyone?
Bill, N3RR
k2we@juno.com wrote:
> I have a question for you pro's out there... Is there a better way to do
> this???
>
> I have a Tri-EX LM-470D 70' motorized crank up... I have a Tic-Ring 1022
> ring rotor mounted on the top of the 3rd section. With the tower fully
> extended (70') The ring rotor is at about 52'.. I have a Force 12 model
> 4BA mounted on the ring rotor... It's a 12 element yagi for 10/12 & 15/17
> meters... It has 2 seperate feed lines..I use a remote coax switch which
> is located at the top of the tower...The 2 feed lines go down from the
> remote switch to the 4BA..
> I have a 6' piece of mast running horizontial fastened to the tower just
> below the thrust bearing... I use this to suspend the coax running down
> to the 4BA on the ring rotor..Every once in a while, the coax gets caught
> in the ring rotor. Of course, when I go to turn the ring rotor, I tear
> the coax...
>
> Question.... Is there a better way to run the coax down to the ring
> rotor?? Should I relocate the remote coax switch down to the ring rotor
> level??? What am I doing wrong???
>
> By the way, I have a Force 12 Magnum 520/340 at the top of the tower...
> It too has 2 feedlines...Is it better to run them down to the coax swich
> or will I have the same problem???
>
> I'd love to hear from any other Ring Rotor users where it's installed on
> a crank-up tower...How have you siolved the coax problem??? I've been
> installing towers and antennas for 30 + years.. I'm just a bit puzzled...
>
> By the way, I'm using an 18' piece of 1/2" wall, aluminum mast. I have 6'
> below the bearing with the remaining 12' above the bearing...I was able
> to purchase the mast from a local reynolds aluminum distributor on Long
> Island for $85 .. I was amazed to find they come in lengths up to
> 36'!!!.. Before this installation, it held a 4 element mosley 2 meter
> yagi on a 36' boom and a Cushcraft 2 element 40 meter beam.. It's held up
> very well in the worst winds for almost 8 years...
>
> I'd love to find out if there is a better way to route the coax to the
> beam on the Ring Rotor.... I'd entertain a phone call at 914-693-3669
> after 9PM EDST
>
> Thanks in advance.....
> 73.. Steve/K2WE
>
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