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    Replacing the feed horn
    #1
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    I'm replacing the c/ku Chaparral corotor II feed horn with a new genuine one. Noticed that the scalar ring in wider/thicker then the 8 years old one from TEK2000 store, witch I believe was a used one to begin with (see screw marks):
    [Only registered and activated users can see links. ]
    My question is if there is any procedure &/or tools, to install the new scalar ring parallel and centered to the face of the dish.
    I'm thinking about a laser pointer (beam) !!
    Forgot to mention that last month we had 2 tornados in the area; 1 small branch slightly bent 2 holding arms and knocked
    off the feed horn assembly: cone cover on the ground, so I assume that the hole assembly is out of the alignment. The signal is a bit less then before. I also had to replace the servo.
    Any input is welcome.Thx.
    Last edited by lme; 10-26-2023 at 02:19 PM.
    Nihil sine Deo !
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    #2
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    For the scalar. 3 or 4 tape measures around the dish rim and a lot of patience. Or perhaps some el-cheapo fiberglass driveway marker poles from tractor supply with sharpie or printed paper markings taped to them. And patience.
    To get the feed pointing straight at the dish center. I used paint can tops that fit the feed tube. Punch a hole through the center dimples. Tape a few together. Measure and cut a 'glass pole or wooden dowel. Stick it through the holes. You'll be very close. Try to get max signal aiming the dish and then tune the lnbf in.

    Edit:
    Thanks guys. That was a pretty sucky description. A few rulers around the dish rim that extend to a reference point on the scalar. Perhaps big binder clips or gorilla tape to hold them in reference to the rim.. I like EB's method of long bolts and nuts on the dish face to give fine adjustments. On my button hook feed, my adjustment bolts are on the scalar.
    There's my spray paint can top jig I just dug out of the pile. I don't think it would fit inside of the Chaparral feed tube w/o interfering with the....."butterfly???....just inside it. But you're a smart guy. You'll figure it out.
    Brain fart. Why not find a flat disc of metal that would sit in the scalar center with a center hole drilled and use the can tops? Or since it 'tis the season. A couple of nut cans taped together with center holes and a dowel. The open end of the first one sitting inside of a scalar rib.

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    Last edited by ArloG; 10-26-2023 at 11:18 PM.
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    #3
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    Thx.
    Where can I read "I like EB's method of long bolts and nuts on the dish" ?
    Nihil sine Deo !
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    #4
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    I forget. It was recent. Not that hard to figure out. But. Do your feed mount poles extend from the dish face or rim?
    Look at my photo. My buttonhook feed is modded to allow scalar adjustment. It was a pic from when I first put it all together before alignment.
    The adjustment bolts and lock nuts would be duplicated on the dish face if that's where your poles are bolted.[Only registered and activated users can see links. ]
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    #5
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    The poles (4pcs), are bolted on the dish face.
    I think I found a way to check if the scalar ring is centered: a magnetic inclinometer with laser line on each end snapped
    on a big washer with same diameter as the feedhorn hole in the scalar. Holding this assembly with 1 hand and bending the scalar with the other hand. I already have 4 lines on the center plate of the dish: 1 set for polar axis and 1 set for the lower west sat (139w) as a service position. Each set are 2 perpendicular lines converging in the center of the center plate. As far as can remember when I got this 10' used dish, the name was StarTrak ?!?. Can't find any info on the web, but found ass'y instructions for a Perfect 10 dish, and the mesurrements look similar to my mesurrements.
    Mesurrements on 4 points from the rim to the outer ring of the scalar are equal.
    Tomorrow will try to install the new corotor II. Found an idea of an empiric tool to check if the feedhorn is centered:
    an oil filter cap (#5) will fit over the horn, and I enlarged the hole for the wrench in the cap to fit a pet laser pointer.
    Will check it tomorrow and confirm if the scalar is centered. Hope to have tomorrow another day of the indian summer !!
    Nihil sine Deo !
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    #6
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    The scalar ring helps hold the parabola of a mesh satellite dish.To see this, string the dish without the scalar ring installed, then install the scalar and string it again. Most likely, the strings will show a different dish shape with the scalar installed as compared to the scalar not installed.

    Almost all of the scalar rings that are shipped with a c band lnbf are of poor quality and design. More weight in metal = more production costs. LNBF's are for the most part, cheap items when compared to lnbs. A lnbf is usually made using the cheapest parts and cheapest methods available. There are of course a few exceptions.

    Here are two pictures of scalar rings for c band, The smaller one was shipped with a lnbf.
    [Only registered and activated users can see links. ]<---------------------->[Only registered and activated users can see links. ]

    Here are two pictures that show the difference in depth. Look at the depth markings on the lnbf:
    [Only registered and activated users can see links. ]<---------------------->[Only registered and activated users can see links. ]

    There is a noticeable weight difference between these two scalar rings. The scalar ring helps to hold the correct dish shape on most mesh satellite dishes. The better the scalar ring is mounted, the better the dish performance.
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    #7
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    The scalar needs to be mounted dead-center of the dish if possible. This can be hard to do when the dish is off the ground and aimed at a satellite.

    Washers can be installed at the top to lower the scalar. Washers can be installed at the bottom to raise the scalar, depending on how the feed arms are mounted. Any washers that are installed to raise or lower the scalar ring should be a temporary fix because they will reduce stability. Find out where things are supposed to be, then make or get someone to make the proper mounting arms for the dish. We cannot get dish parts anymore, so we have to make them!

    here is a scalar ring mounted to feed arms that have slots in them. These slots allow the scalar to slide so it can be centered. The arms should be an equal distance in degrees around the dish. The arms are not an equal distance on this dish.
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    String the dish at several angles to see if the shape has changed after installing a scalar ring.
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    #8
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    By mistake (or not !), the seller sent me a corotor 2 plus wideband.
    Can this be used for north american satellites ?
    He's insisting that should be no problems....
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    #9
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    The corotor 2 plus wideband will work, but it will not be as sensitive because it is designed to work over a longer frequency range.
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    #10
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    Quote Originally Posted by el bandido View Post
    The corotor 2 plus wideband will work, but it will not be as sensitive because it is designed to work over a longer frequency range.
    So it is not recommended to be used in this place...
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