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Discussion Starter #1
I am trying to help a friend who is using a 75cm Starchoice elliptical dish to try to find non Starchoice satellites, using the Bell legacy lnb. I know that the arm which holds the lnb is pointing below all satellites, but how much? I guess that I am asking for the offset. Someone told me 23 degrees, can someone confirm that? TIA.
 

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I don't have the degree answer but if your friend is looking for FTA - (free signals) he/she will most likely be wanting to use a linear LNB and not Bell's circular LNB. The Bell circular LNB being used is pretty much only good for Bell and Dish Network satellites.
 

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Discussion Starter #3
Yes, we realize that we need to try different lnbs. Basically, we are just fooling around on nice days, trying to find out what is up there. Bell is a possibility some day, there is concern about line of sight. So, I am still looking for the degrees.
 

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Use dispointer . com and you will be in the ball park with their settiings for whatever you are trying to find.
 

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On a standard Shaw dish the eye of the LNB that is in line with the support arm is to be pointed at Anik F2 at 111.1. The eye that is offset will then pick up the signal from Anik F1R at 107.3. There is only a 4-degree separation between the satellites that Shaw uses.

Not sure if that's what you're asking or not........
 

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I think the offset is the 23 or maybe 21 degrees.
No matter, just use the elevation setting on the back mount of the dish for aiming.
Also ensure that a non oem LNB when mounted is able to point at the same focal point on the dish. Since the dish is wider than higher, your taget is quit small.

If the mount is the type that wraps around the neck of the LNB, then that's best as it preserves the focal point.
Using the the original quad with it's plastic insert to the rectangular tube can be a bear to adapt.

If you are 'scoping' thing out, try an Invacom LNB that has 2 circular and 2 linear outputs from the same LNB on a 33" or 1 M FTA pan (since they are light and cheap) with a motor.
Than once setup, you can scan the horizon and it takes care of elevation for you as it follows the arc.
 

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Discussion Starter #7
Thanks, but here is what I am asking. Let's pretend that the moon is a satellite that is transmitting a signal to earth and it is at 30 deg elevation compared to the horizon.. If I sight down the lnb arm like I'm using a rifle, and the moon is right in the sight, I know that I will actually be much too high to receive the moon's 'signal' because of the offset. So how high (compared to the horizon) should I aim the lnb arm ... 7 degrees (30-23), or what?
 

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Put a drywall square across the face of the dish with the arm out perpendicular.
Then measure the angle of the arm/lnb to that to find the offset.
Use either a protractor or using some good old fashion trigonometry.

Usually if you get with a couple of degree vertical, you will lock onto a signal.
Then peak up or down.
Or use a good compass, find the azimuth and work up/down.
Identify the satellite using whatever means.
I like old FTA receivers that can read many transponder ID's. or out of service Bell/dish receivers that also read sat id's.
Then check the elevation published for that bird and your location and compare against the elevation marking on the back mount of the dish and recalibrate if needed.
 

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I was able to pick up 82 & 91 separately in Red Deer, AB on a 30x33 circular *C dish. The elliptical version operates on the same theory. Set your elevation 7 degrees higher than you normally would for Bell-here in Red Deer it runs around 30 and start moving your dish until you pick up signal with your legacy LNB (rectangular feed?). Peek it and voila!
 

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while simply swapping an lnb will probably give you some signal, it probably won't get you the best signal. having the lnb pointing directly into the exact center of the dish ensures that it "sees" only signal reflected off the dish and not background noise from the wall or the ground behind the dish. you would also notice that the old lnb that was originally on the dish had a clamp around it's neck that allowed it to not only rotate for the best skew but you could slide the lnb nearer or farther from the dish to get it precisely in the correct focus. whenever i've converted a big old 30" round dish to a circular polarity lnb i've broken the grey plastic cover off the lnb and found that there was a pipe with the correct diameter to clamp onto the dish in place of the linear polarity lnb that was there.
the offset angle that you are looking for is something specific to each model of dish. it's also a trick we installers sometimes use to aim a dish. if you know the offset angle, you can subtract that from the elevation setting you are supposed to have and put a magnetic angle meter on the arm of the dish. you then set your elevation to this angle and you will find the satellite easily. it's often a great solution for masts that aren't plumb or the elevation scales on the dish that aren't accurate. even if you don't know what the offset angle is for your dish you can still take that angle meter and put it on the same model of dish that's already aimed properly and remember what that angle is. as long as you don't move more than about 50 miles away from there that angle will probably still be quite accurate
 

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Let me try and explain what I think without a picture...

Now, this is dishes in general, the starchoice dish the you have might actually have a lucky coincidence, but I wouldn't count on it:

The direction that the LNB arm points will be independent of the dish offset angle. The LNB arm is placed at an angle and a length to get the LNB out far enough from the dish, and up high enough from the bottom edge of the dish.

If the dish is "flatter" then the focal point moves out, making the LNB arm longer and placed at a shallower angle. The offset angle could be the same for both the "flatter" and the more concave dishes.

The antenna offset angle is a function of the actual shape of the dish, and while it will move the focal point lower away from the center of the dish, it will not have as much impact on distance from the dish; so you can see that many different LNB support arm angles and lengths are possible for a given dish offset.

Also, the type of LNB and mount can have a big influence - the square tube type like Bell dishes will have a shallower arm angle, because the LNB is sticking up higher - the round collar type mounts will have a steeper angle, because the end of the arm needs to be very close to the focal point.

The best way to eyeball it that I know is to look at the dish from the side, the face of the LNB will be at an angle to the dish - imagine a beam coming straight out of the face of the LNB and bouncing off the face of the dish and up - that is where the dish is "looking" and your offset angle.
 
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