[TowerTalk] Alliance HD73 Rotator calibrate and mast bolt size?

[Gene Bigham]

I brought the rotator down, have examined it and taken it apart, off the
tower it rotates 360 degrees and shows that on the control meter.   I have
lubed the gears with white lithium grease which is what this rotator had
many yu
----- Original Message ----- 
From: "Gene Bigham" <jbigham2 at kc.rr.com>
To: <wc1m at msn.com>; <towertalk at contesting.com>
Sent: Thursday, June 23, 2005 3:42 PM
Subject: Re: [TowerTalk] Alliance HD73 Rotator calibrate and mast bolt size?


> After talking with Norm at RotorNorm, it has been determined the rotator
> took a wind torque hit which has damaged the gear train.  This means
taking
> the tower back down disassembly of rotator, antenna, mast.  Correction of
> damaged rotator, reassembly, and putting tower back up.
> I have a local ham who does this sort of thing coming over this evening to
> take a look at what needs done.  I am partly disabled so can't do this
sort
> of thing like I used to and need additional help.
> Thanks for the comment, but the coax loop is in no strain I made sure I
had
> an ample turn loop.  It is definitely the innards of the rotator.  Too bad
I
> have had this rotator for probably 15 years or so.
> Best Regards
> KB0GU
>
>
> ----- Original Message ----- 
> From: "Dick Green WC1M" <wc1m at msn.com>
> To: "'Gene Bigham'" <jbigham2 at kc.rr.com>; <towertalk at contesting.com>
> Sent: Thursday, June 23, 2005 12:30 PM
> Subject: RE: [TowerTalk] Alliance HD73 Rotator calibrate and mast bolt
size?
>
>
> Sounds like the antenna has slipped on the mast, the mast has slipped in
the
> rotor jaws, or the lower rotor jaws have slipped on the pipe -- or any
> combination of the three! If you expect winds like that in the future, you
> might consider using bolts to pin the antenna to the mast, the mast to the
> rotor and the rotor to the pipe. This will require some drilling. There's
> probably a hole for this in the A3S boom-to-mast bracket. Can't recall
> offhand, but I think there are holes for pinning in the HD-73 upper and
> lower mast clamps.
>
> You need to calibrate the controller before you have the antenna (or
rotor)
> moved back to the correct heading. In other words, you have to know where
> the rotor "thinks" the antenna is pointing before moving the antenna to
that
> heading. The symptoms you describe indicate that the controller is still
not
> properly calibrated. I'm speculating here, but the symptoms also suggest
> that the reason you can't calibrate the controller is that the coax loop
has
> reached the end of its travel! My guess is that this is happening when you
> move the antenna to the west and could explain why the rotor slows down
near
> the end of travel. To see if this is the case, rotate the antenna to
within
> 10 degrees or so of where it slows down at the west end then go outside
and
> see if the coax is stretched near its limit. If not, then rotate the
antenna
> all the way until it stops at the east end and see if the coax is
stretched
> near its limit.
>
> If you find that the coax is the reason for the stop in travel, and it's
> only happening at one end (probably the west side), then simply rotate the
> antenna until it reaches the rotor's mechanical stop at the opposite end
of
> travel (probably the east end.) When you do this, make absolutely sure the
> rotor is stopping because it's at a mechanical stop and not because it's
> yanking on the coax. Then have your tower climber loosen the rotor clamps
> and turn the mast due south. This should relieve the tension on the coax
> when the rotor reaches the other end. Recalibrate the meter as detailed
> below.
>
> If the coax is not stretched to its limit at either end, then my theory is
> wrong and the most likely explanation is that you have miscalibrated the
> controller -- probably turning the meter adjustment screw too far from
where
> it should be. In that case, follow the meter calibration steps below.
>
> METER CALIBRATION: (Do this only when you are sure the coax loop is not
> limiting rotor travel!) 1.) Rotate the antenna until it reaches the end of
> its travel on the west side. 2) Adjust the small screw below the center of
> the meter to make the needle point due south on the west side. 3) Rotate
the
> antenna all the way to the east end. 4) Use the calibrate knob to set the
> needle to due south. 5) Leave the rotor pointing due south and have your
> antenna guy move the antenna due south by loosening the rotor clamps and
> rotating the mast.
>
> If none of the above helps, then there is another possibility. The HD-73
> uses a simple friction braking system. In high winds, the brake can slip.
> This is not a huge problem if the rotor doesn't turn too far -- it's just
as
> if you had moved the rotor with the controller. But I don't know what
> happens if the rotor turns to one of the stops and high winds continue to
> push the rotor against the stop. It's possible there would be enough
> internal damage to cause the symptoms your are seeing.
>
> Hope this helps.
>
> 73, Dick WC1M
>
> > -----Original Message-----
> > From: Gene Bigham [mailto:jbigham2 at kc.rr.com]
> > Sent: Wednesday, June 22, 2005 7:05 PM
> > To: towertalk at contesting.com
> > Subject: [TowerTalk] Alliance HD73 Rotator calibrate and mast
> > bolt size?
> >
> >
> > The recent round of 80 to 90 MPH straight line winds in our
> > area has caused a misalignment of my rotator direction
> > indicator and the actual antenna position.
> >
> > First, the indicator is centered on North and can go on the
> > meter to the (left) South of West and on the (right) South of East.
> >
> > Right now playing with the calibrate knob and turning the
> > antenna, the azimuth indicator needle will travel to and show
> > South (of East) but the antenna and rotator stop at about the
> > 130 to 140 degree position and remain there, tracking of the
> > sweep of the indicator needle seems linear from North to the
> > stop point.  But the antenna will not advance past 130 or so
> > to due South 180 degrees.
> >
> > On the other side of the indicator when I rotate back past
> > North toward South (of West) the indicator arrives at South
> > with a deceleration of the degrees traveled compared to the
> > indicator as the antenna moves past north to north west then
> > west, and finally ends up at south west say 210 to 220 and
> > stops shy of South.
> >
> > I initially tried to use the calibrate button to adjust this
> > but the above results are the best I can get.
> >
> > This is Alliance Model HD 73 and has been pretty bullet proof
> > until now.
> >
> > The rotator initially torques on top of my Aluma tower top
> > section in heavy wind storms until my antenna guy put a
> > couple of self tapping large screws through the top plate and
> > against the lower bell housing of the rotator to limit the
> > rotation of the rotator on its mounting pipe.  This rotator
> > sits on top of the top plate using a lower pipe mount, the
> > bottom of the bell housing just sets on the top plate while
> > the pipe goes down into the tower and is secured to the tower
> > legs using U bolts to all three tower legs.
> >
> > There are two options I am thinking about to correct the alignment.
> >
> > First, place the indicator and rotator as far to the South
> > (of West) position and then loosening the mast clamp and
> > manually align the antenna to true south since the
> > correspondence of degrees measured to degrees turned is
> > different on this side of the rotation.
> >
> > Or Second, place the indicator and rotator as far to the
> > South (of East) position and align the antenna to true south
> > loosening the mast clamp.
> >
> > Which way am I safe to presume will correct full range of
> > rotation and more accurate correspondence to the measurement
> > scale?  I can get someone to turn the antenna in the rotator
> > to true South when the indicator is in either the South (of
> > East) or (West) position.
> >
> > Anyone familiar enough with this rotator to assist?
> >
> > The antenna is A3S so precise pointing is not absolutely
> > required, rather ballpark pointing.  At this point I cannot
> > cover the last 30 to 60 degrees across the south stops.
> >
> > And if you know the bolt size on the bolt heads securing the
> > mast pipe I can send my painter friend up his ladder against
> > the tower, as climbing this small tower is impossible, with
> > the correct socket!  So he can loosen then move and tighten
> > the antenna into place.
> >
> > If I am incorrect in this entire diatribe please let me know
> > your ideas.  I plan to attempt this move tomorrow evening.
> >
>
> _______________________________________________
>
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>
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