Aiming Starband dish with skewable mount (1 Viewer)

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thisBUDsforyou

SatelliteGuys Guru
Dec 9, 2007
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I have a Starband dish (Channel Master 74E type) with skewable mount. Over the weekend I removed the factory LNB which is very heavy with a transmitter included and replaced it with a Sadoun KL2 dual linear LNB, attaching it to the LNB arm with a fabricated metal plate and stainless steel hose clamp. I had a lot of trouble finding G25 at 97W. I set the skew at +24, then started panning left and right, adjusting the elevation, panning again. This went on for a couple of hours, then I gave up on that approach. I had a compass several feet in front of the dish, pointed the dish as accurately as I could in the right compass direction, then started doing blind scans with my Mercury II at different elevations. I finally scanned in some transponders and some TV stations which turned out to be for SatMex 6 at 113W. This really surprised me because 113 and 97 are 16 degrees apart. I've pointed regular non-skewable dishes successfully a number of times now and have never been even close to that far off on compass direction. The other thing that puzzles me was how I was able to receive SatMex 6 which needs a skew of something like +40 here when I had the skew set at +24 for G25.

I fine tuned the elevation and azimuth to peak 113, then working from there knew I had to increase elevation by 8 degrees and move left 16 degrees to get G25 and I finally got it. G25 is at 39 elevation from here (Philadelphia area) but the elevation on the dish mount read 46, off by a good 7 degrees. And yes, the mast was plumb, it was mounted on the side of a rickety pallet used as part of my compost bin but I had used a coat hanger and turnbuckle to jack the mast with that heavy dish on it up to plumb in all directions. Maybe the non-factory jury-rigged LNB changed the needed elevation for the dish.

But my basic question for y'all is this: when you have a dish with a skewable mount, does that change the compass direction you point the LNB arm at? With the dish skewed, does that change the angle the signal comes in at?

Thanks much on any advice.
 
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Mr Tony

SatelliteGuys Pro
Supporting Founder
Nov 17, 2003
295
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Mankato, MN
But my basic question for y'all is this: when you have a dish with a skewable mount, does that change the compass direction you point the LNB arm at?
no
With the dish skewed, does that change the angle the signal comes in at?

no

If the dish can skew, buy all means do it. Gives more signal than if you just twist the LNB.

I have a StarChoice dish that is skewable and when I aimes the dish it was the same elevation as a non skewable dish
 

Anole

SatelliteGuys Master
Sep 22, 2005
11,819
12
L.A., Calif.
On a skewable dish, if you set the skew to zero, and point the dish south with your compass, it'll be right on.
Now, let's say you skew the dish over 90 degrees.
It's still pointing south.
But, which way is the LNB arm pointing?
The dish is supposed to still be pointing south, but you'll be fooled by the LNB arm.

Next thing to screw the pooch is the LNB mounting location.
If you didn't locate your LNB at exactly the same height as the original, then you've effectively messed with the elevation.
But what's worse, is that the skew mount was calibrated for the LNB being in the right place and now it isn't.
So, as in the example above (set skew to zero, point south, then skew the dish), you will no longer be pointing in the correct direction NOR have the correct elevation.
 

neftv

SatelliteGuys Pro
Dec 9, 2005
199
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PA USA
thisBUDsforyou,
I can't answer any of your questions but I am interested in how you mounted that LNB to the feed horn. I have the same dish. Is it possible for you to take some close up pictures of it showing exactly how you did it and the individual parts if possible, Thanks a bunch.
 

thisBUDsforyou

SatelliteGuys Guru
Dec 9, 2007
141
0
First off, thank you Anole! You are a great help on this board, and I've learned a lot from your posts.
On a skewable dish, if you set the skew to zero, and point the dish south with your compass, it'll be right on.
Now, let's say you skew the dish over 90 degrees.
It's still pointing south.
But, which way is the LNB arm pointing?
The dish is supposed to still be pointing south, but you'll be fooled by the LNB arm.
Yeah that's kinda what I thought given how much trouble I had. There must be some trick to getting compass direction right with this kind of dish when you skew it. Or maybe it's enough to know that when the satellite is way to your west you need to point it a fair bit east of where lining up the LNB arm with a compass would leave you to believe. I can't point the dish with zero skew and then change the skew because I had to fabricate the clips that hold the dish to the mount and once I tighten up on them they kinda get stuck and in order to change the skew I have to take the dish off the mast and bang on it a bit to get the clips to come loose.
Next thing to screw the pooch is the LNB mounting location.
If you didn't locate your LNB at exactly the same height as the original, then you've effectively messed with the elevation.
But what's worse, is that the skew mount was calibrated for the LNB being in the right place and now it isn't.
So, as in the example above (set skew to zero, point south, then skew the dish), you will no longer be pointing in the correct direction NOR have the correct elevation.
You're right, the LNB is probably not in the exact location that the original one was which changes the elevation scale but it seems I should be able to just adjust for that. Now I know, for example that for 39 elevation I need to raise the dish all the way to 46 on the elevation scale on the mount. As for the skew being off, this dish seems fairly forgiving - I was able to pull in SatMex 6 pretty well even though the skew wasn't even close to being right.

Bottom line this is a terrific dish. Once I finally found G25 I got very good signal quality and it locks on all those channels rock solid, even after passing through 2 switches and 150 feet of coax. The mount is real heavy and well made and I like that it has a jack bolt for fine adjustment on the elevation so you can adjust it just by giving the jack bolt a quick turn with a wrench, unlike other mounts where you loosen bolts on either side and risk having it slip way more than you wanted to when you get down to making fine adjustments.
 

Anole

SatelliteGuys Master
Sep 22, 2005
11,819
12
L.A., Calif.
Yea, I wasn't disparaging the dish.
I love the entire family of molded dishes.
That mount sounds great, too.

I'd say (others are welcome to comment) that if you don't need more than 10..15º of skew and your target bird is pretty hot, don't skew the dish.
Save yourself the headache.
That's assuming you are able to skew the LNB independently.

But, if you need a lot of skew (say, 20º or more?) , AND the signal is weak, then maybe skewing the dish is worthwhile.
You'd have to run some tests to see how much skew and how weak , as this is only a guess.

You certainly do gain performance by skewing the dish, but since doing so is a pain, avoiding it may be worth while.

A while back, someone posted a suggestion for seeing which way an offset dish was aimed.
If it's even close to accurate , it would help out.
The idea was to take a yard stick and rest it at the base of the dish where the LNB arm is attached, and across the top of the LNB.
I have thought about the idea, but not worked out in my mind that this is always true for all size/shape dishes, but my gut feel is that it's NOT true.
However, it's a heck of a lot closer than looking at the LNB arm, so if it helps, for now it might be worth a try.

As for getting your LNB in the right place, I used an idea first presented on this forum by Z4cCamaro.
See this thread for my interpretation of his idea, and a discussion with him of some variations.

There are tons of great ideas posted within threads on the forum, but it'll take some general exploring to find 'em all.
Linuxman and dual Sky Mexico LNBs on 87 / 97
http://www.satelliteguys.us/free-air-fta-discussion/99108-87w-97w-primestar-84e-multi-lnbf.html
Linuxman and dual LNBs on 123 / 129
http://www.satelliteguys.us/free-air-fta-discussion/97742-123w-129w-1-meter-primestar.html
 

thisBUDsforyou

SatelliteGuys Guru
Dec 9, 2007
141
0
thisBUDsforyou,
I can't answer any of your questions but I am interested in how you mounted that LNB to the feed horn. I have the same dish. Is it possible for you to take some close up pictures of it showing exactly how you did it and the individual parts if possible, Thanks a bunch.
Here ya go. In the second picture you can see that all I used was a metal plate I had lying around and a hose clamp which I bought at Home Despot for about a dollar. I drilled three holes in the metal plate, two to go in the holes in the LNB arm (I used the original Philips head screws) and one in the center to bolt the hose clamp to. The last two pictures show the original feed horn/ LNB assembly. In the fourth picture you can see my fabricated clips on the back of the dish.
 

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Anole

SatelliteGuys Master
Sep 22, 2005
11,819
12
L.A., Calif.
See how your Sadoun LNB sits higher than the original?
That makes your dish aim lower (mirror effect)
So, you had to increase the elevation to make up for the down-looking LNB.
Get that LNB neck down in the original half-moon curve at the end of your bracket, and it'll probably fix both problems.

Sometimes ya need to take the large diameter plastic off the neck of some LNBs, exposing the small diameter throat tube, and that may fit the half-moon better.
I don't have one here, but you can tell from inspection, what needs to be done.
Iceberg has posted on the subject a number of times.
Maybe you can find one of his pictures where he did that very thing (though, maybe on a different dish).

Or, if it works, leave it alone, 'cause you're done! - :up
 

thisBUDsforyou

SatelliteGuys Guru
Dec 9, 2007
141
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You're right of course. And if I did all that I'd be closer to the original design specs of the dish and probably would get a smidge more signal. But you know what? I'm lazy and it works the way it is.
 
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neftv

SatelliteGuys Pro
Dec 9, 2005
199
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PA USA
Here ya go. In the second picture you can see that all I used was a metal plate I had lying around and a hose clamp which I bought at Home Despot for about a dollar. I drilled three holes in the metal plate, two to go in the holes in the LNB arm (I used the original Philips head screws) and one in the center to bolt the hose clamp to. The last two pictures show the original feed horn/ LNB assembly. In the fourth picture you can see my fabricated clips on the back of the dish.

Wow thanks. question. Instead of having the center bracket that you drilled 3 holes is it possible to bolt the hose clamp with the original philips head screws the feed horn directly on the mount so it sits lower. The Pipe clamp is like an upside down U and bolted to the mount directly that way. Or are the phillips bolts mounting to close to each other to do that?
 

Mr Tony

SatelliteGuys Pro
Supporting Founder
Nov 17, 2003
295
43
Mankato, MN
Sometimes ya need to take the large diameter plastic off the neck of some LNBs, exposing the small diameter throat tube, and that may fit the half-moon better.
I don't have one here, but you can tell from inspection, what needs to be done.
Iceberg has posted on the subject a number of times.
Maybe you can find one of his pictures where he did that very thing (though, maybe on a different dish).

ta da ;) Cut the casing from behind the eye like the pic and that will fit right into the 25m slot on the dish
 

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Mr Tony

SatelliteGuys Pro
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Nov 17, 2003
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Mankato, MN
yep the LNB is sealed so even if its "naked" (no casing at all) its sealed tight.

While back I had a couple Dish dishes up (when I had a Dish sub) and the LNB's I used had no casing on them

last pic is a KU LNB that I gutted because it was bunk :)
 

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Anole

SatelliteGuys Master
Sep 22, 2005
11,819
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L.A., Calif.
pix of hardware

Thanks, Iceberg. Great pictures. And since a pix is worth a thousand words... ;)

This link on our forum shows several views of that -U- bracket discussed above.
It should be fairly cheap, and apparently comes in a size that fits a Primestar spacing pretty well.

And this picture is another thing you'll find in the hardware store.
I think it's part of a grounding clamp. (suggesting you get -two- of the brackets for your purchase)
Might cost more, but if you're only using one, then who really cares if it's 50¢ or $5 ?
As long as it gets the job done!
. . . and looks stylish . . . - :eek:

edit: giving credit where credit is due:
George, that ground clamp idea was pure genius.
I found the above ones at Lowes this morning for $1.67.
I modified it just a little, but now have two working halves to use and have a spare for more dishes.
The holes line up perfectly, and they are solid without being too thick like the original.
 
Last edited:

Tron

SatelliteGuys Master
May 6, 2005
6,599
33
Metro New Orleans, LA
There's another solution that you can try, use the original feedhorn with a C-120-flanged LNB. You would unbolt and remove the waveguide, transmit, and receive (since its a single-polarity rig) LNB, and replace that whole assembly with a C-120 flanged LNB such as a Primestar 'beer can' or Hughes.
 

thisBUDsforyou

SatelliteGuys Guru
Dec 9, 2007
141
0
Thanks guys. I'm planning eventually to mount this dish on the back wall of my garage for G10. Now I've got some thinking to do as to which of these great ideas I'm going to use for the permanent installation.
 

thisBUDsforyou

SatelliteGuys Guru
Dec 9, 2007
141
0
ta da ;) Cut the casing from behind the eye like the pic and that will fit right into the 25m slot on the dish
Boy that seems awfully violent. Before, I was thinkin' Sadoun ought to send me a check for the free advertising I was doing for their LNB. They'd want their money back if I take a hack saw to it and post pictures of that!:rolleyes:

Now an even more awful thought occurs to me. I have another Channel Master dish, a PrimeStar that's slightly larger than the Starband dish in this thread. I'm guessing it has the same 25 mm LNB throat. I was thinking of motorizing it with an Invacom quad LNB. I could do the same thing - cut the casing off .... off of my $56 LNB ???? Maybe not.
 

thisBUDsforyou

SatelliteGuys Guru
Dec 9, 2007
141
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Another thought - doesn't anybody make a LNB any more that has a 25 mm throat to begin with so you don't have to cut it?
 

Mr Tony

SatelliteGuys Pro
Supporting Founder
Nov 17, 2003
295
43
Mankato, MN
Boy that seems awfully violent. Before, I was thinkin' Sadoun ought to send me a check for the free advertising I was doing for their LNB. They'd want their money back if I take a hack saw to it and post pictures of that!:rolleyes:

Now an even more awful thought occurs to me. I have another Channel Master dish, a PrimeStar that's slightly larger than the Starband dish in this thread. I'm guessing it has the same 25 mm LNB throat. I was thinking of motorizing it with an Invacom quad LNB. I could do the same thing - cut the casing off .... off of my $56 LNB ???? Maybe not.

it doesnt hurt anything and if you need to put it back to a 40mm most LNB holders have the adapter for them...or the handy dandy duct tape always works too :)
 
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