I have a single 8-wire cable run of about 350 feet, and I've not have any
false/missing pulse problems with an M2 OR2800PX turning a 16 sq ft antenna.
But read on.
After deciding that the M2 OR2800PX was otherwise the best rotor for my
application, I did some research and found that the false/missing pulse
problem definitely exists. Some have said it affects only the older AC
models, but that's not true: it's been verified in the DC models as well.
One ham I consulted was able to tune out the noise with capacitance, but
that may be hit or miss depending on the cable length/inductance. The only
consistently successful solution seemed to be using two separate cables, as
Frank recommends. Quite a few Orion users have had success using a separate
small diameter coax run for the pulses.
But the best information I got on this problem came from Green Heron
Engineering. Lucky for me, I had already decided to buy a Green Heron
controller instead of the stock controller. I had witnessed several Orion
controller failures over the years at multis, in one case with very bad
consequences for the feedline of a large array being turned with a prop
pitch that freewheeled. Having had great success with Green Heron
controllers on my three TIC rings, and considering that M2 has the
enlightened policy of offering the rotor optionally without the controller,
it was more or less a no-brainer to get the GH controller.
Here's what Jeff of Green Heron told me about the Orion M2 OR2800PX (and I
hope he doesn't mind being quoted):
" You will not have counting problems with an Orion when using an RT-21. I
have firsthand experience with Orions and I have 4 of them up here,
including a really old OR 2300. They are the ultimate in reliability when
used with the GH controller."
and
"There may actually be three failure modes.
I agree it's not RF, it may be three separate things.
Thing 1. For large antennas, the Orion stops counting pulses too
soon...while the antenna is still moving. I've proven this on a number of
occasions.
Thing 2. There's no margin in the bias design.....slight cable leakage
(between the pulse leads OR from motor to pulse) of even as little a Meg
Ohm, will cause miscounts.
The GH Controller fixes both of these. I can run our controller on
non-shielded cables running 500-600 feet with as little as 200k leakage, and
it works fine......I have the dead groundhog here to prove it...(well, at
least a picture of the dead ground hog to prove where the cable leakage came
from.)
Thing 3. -... (on tuning out the noise with capacitance) I haven't seen
where tuning the capacitance can work....but I didn't try that. OR maybe
sometimes they get lost in software somehow...haven't been able to prove a
third cause. A 4.7 uF tantalum should destroy the edges of the pulse, maybe
he's fine tuning the inductive coupling of his specific line length. In any
event, I don't think he'd see the same thing with our controller.....
I have shipped maybe 40 controllers to guys with counting problems with the
same full money back guarantee if it didn't fix it. None have come
back!!!! We use the same scheme for Prop Pitches where the motor pulses are
4X the current as in an M2 rotor. They never miss pulses counts there
either. Even on 600' runs of non-shielded cable with the pulse wires in
with the motor wires.
Maybe our Pulses aren't as square.....Another Orion Symptom is receiver
noise that we seem not to suffer from. I really don't know why this might
be. We know this is also true of the Prop Pitch systems between the M2 and
the GHE controller.....receive noise goes away!
Some guys have never had pulse problems. I suspect for smaller antennas
where #1 isn't a problem. As long as your cable is tight and at least 1 Meg
or higher between conductors in terms of leakage (no water in the cable),
then it works fine."
My understanding is that M2 has fixed a lot of problems with the rotor and
the controller, and I confirmed this when inspecting my rotor (one problem
they fixed was that the bolt pulling up the drive shaft would break, and
with the shaft dropped down the limit switch arm would destroy the limit
switches! Can't happen with the new model.) I've heard that they've fixed
some hardware issues and firmware bugs in the controller, too. But I wasn't
able to confirm that they've fixed the missing pulse problem.
My advice: if it's not too late, buy the rotor without the controller (or
return the controller for a refund) and buy a Green Heron controller (I have
no connection to or interest in GHE, etc., etc., just a very satisfied
customer.)
Of course, YMMV.
73, Dick WC1M
> -----Original Message-----
> From: donovanf@starpower.net [mailto:donovanf@starpower.net]
> Sent: Sunday, April 05, 2009 5:58 PM
> To: towertalk@contesting.com
> Cc: W5WZ@arrl.net
> Subject: Re: [TowerTalk] Need rotator cable - 350 ft of 2-12 & 2-18 for M2
> Orion 2800
>
> Scott,
>
> You will have problems with inaccurate rotator position indication if you
use
> 4 wire cable on the Orion 2800 rotator. Noise from the motor causes the
> position indicator to read false pulses if the two small wires are in the
> same cable as the large motor wires.
>
> I use two separate cables on my Orion rotators. The position indicator
has
> been completely trouble-free, despite the 500 foot cable lengths.
>
> 73
> Frank
> W3LPL
>
>
>
>
>
> ---- Original message ----
> >Date: Sun, 5 Apr 2009 13:55:21 -0500
> >From: "Scott Dickson, W5WZ" <W5WZ@arrl.net>
> >Subject: [TowerTalk] Need rotator cable - 350 ft of 2-12 & 2-18 for M2
Orion
> 2800
> >To: <towertalk@contesting.com>
> >
> >I need 350 ft of rotator cable for the M2 Orion 2800. For this length,
the
> >manual recommends minimum of 2-12 and 2-18. The Wireman is the only
source
> >I've been able to locate.
> >
> >Are there others?
> >
> >--Scott, W5WZ
> >
> >
> >_______________________________________________
> >
> >
> >
> >_______________________________________________
> >TowerTalk mailing list
> >TowerTalk@contesting.com
> >http://lists.contesting.com/mailman/listinfo/towertalk
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