dish alignment (1 Viewer)

johnnynobody

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The glass is not half empty...
For a few hundred dollars, the Dr. HD 1000S and 500 combo models have spectrum analyzers that puts the XR-3 to shame. 30fps!

Need to look at a range of the spectrum, not a tiny slice.

And those meters probably have some cons also. I'll stick with the XR-3 for now.
 

johnnynobody

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You want to find solutions or keep swinging at the piñata?

I try to go the cheap route when possible. I'm not going to spend hundreds of dollars for test equipment that may or may not help and will likely collect dust more than anything else. ;) Besides, I need to spend some bucks for a canopy tent so I can assemble the new TEK without getting too roasted.....The UV blocking ones aren't cheap.
 

johnnynobody

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Something isn't set to the right settings, or assembled correctly. Take a LOT of photos of the dish & mount, and post them. Maybe we can catch it.

Here ya go:

The declination bolts measurements appear to be the same. I can't say that I trust the digital measurements for inclination/declination but it gives ballpark measurements. The digital and analog measurements for the pole check pretty much agree along with a bubble level. The analog inclinometer is difficult to read precisely. Before my feed centering rod broke, the feed center was maybe a couple inches off. I'll have to do the centering check the hard way unless I can come up with something like a laser to check feed centering - might have to try fabricating something.
 

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primestar31

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Just quickly scanning through your pics, it seems obvious that your feed scalar is NOT parallel to the dish, and is NOT pointing at the center. That alone might explain most of your issues. If those are not right, all your compensating with other adjustments is a total loss.
 
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johnnynobody

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Just quickly scanning through your pics, it seems obvious that your feed scalar is NOT parallel to the dish, and is NOT pointing at the center. That alone might explain most of your issues. If those are not right, all your compensating with other adjustments is a total loss.

You've got better eyes than me because it looks OK to me. I sure could use an accurate feed centering device to be sure. There was a laser pointer for feed alignment that was commercially available a long time ago but with the decline in consumer grade C-band usage..... I did come across an old thread where Titanium was looking into building a laser device but that it wasn't good business sense to continue the project. I don't know if I could build a cheap device that will get the job done...
 

primestar31

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I just use a torpedo laser level that shoots the laser out of the bottom. it's strapped onto a piece of perforated angle steel, and shoots through one of the holes, as the laser is on one end, and you need it in the center of the scalar. You then remove the lnbs temporarily, put the laser level on the backside of the scalar, and center it. Then shoot the laser down to the center plate, and line it all up. It cost me about $30 years ago.

Looks at pics 16, 17 and 18 closely...
 

a33

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About the mount angles:
Looks like you've set the axis at latitude=42 degrees, or would that be 40.8?? (What is the difference between the two photos?)

And the 46.10 is the {latitude + declination-offset} angle?

Didn't you use the angles that were given to you in this linked post? :

The 42 would have to be 42.65,
the 46.10 would have to be 48.50 (= 90 - 41.50). (I would measure that at dish face, preferably?)

So I'm not sure how you did set it up. Or have you moved to another location?

greetz,
A33
 
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johnnynobody

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dishpointer.com says the elevation should be 41.6 for 103.0W which would be my "true south" sat at azimuth 179.0 true. My home longitude is 103.633W. KTI manual says to set elevation to 42.7 for true south. I set the declination for 5.9 per the KTI manual. 103.0W would be slightly east for me. I must be doing something wrong because the antenna is pointing west of true south for 103.0W instead of east. When I try to search east of center I can't get anything for 103.0W. I'll have to see if I can find a friend to check my initial true south setup.
 

Brct203

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dishpointer.com says the elevation should be 41.6 for 103.0W which would be my "true south" sat at azimuth 179.0 true. My home longitude is 103.633W. KTI manual says to set elevation to 42.7 for true south. I set the declination for 5.9 per the KTI manual. 103.0W would be slightly east for me. I must be doing something wrong because the antenna is pointing west of true south for 103.0W instead of east. When I try to search east of center I can't get anything for 103.0W. I'll have to see if I can find a friend to check my initial true south setup.
That is indeed strange.. Either your true geographic south is not where you think it is (you might want to verify what the compass is saying with landmarks you can see and google maps). DO NOT rely on the compass in a phone. Or maybe the geometry of the dish is off. Did you do a string test? Also you might want to verify the centering of the feed with a tape measure, not just visually.
 

Titanium

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Use the sun to determine exact true South. ESRL Global Monitoring Laboratory - Global Radiation and Aerosols

If the dish is aimed at true South and 103w is found further to the west, the feedhorn may not be centered.

Use the pole shadow to determine reflector aiming. Align the dish with the true South shadow and observe if the feedhorn is centered on the AZ axis of the reflector.
 
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johnnynobody

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That is indeed strange.. Either your true geographic south is not where you think it is (you might want to verify what the compass is saying with landmarks you can see and google maps). DO NOT rely on the compass in a phone. Or maybe the geometry of the dish is off. Did you do a string test? Also you might want to verify the centering of the feed with a tape measure, not just visually.

I use the longitude readout from GPS to determine true south. I walk about 20 feet in front of the dish a set a stake where the longitude is the same as the dish location - that should be my true south reference. I tried the compass in a phone but found that wasn't very accurate so I don't use any of those apps. I did a string test just a few days ago and that turned out OK. I'm not sure about feed centering though. There doesn't seem to be an easy and accurate and inexpensive way to set it. I'm trying to fabricate a laser pointing solution - see the images of my first attempt. I don't think a tape measure is a very accurate way to center the feed but I'll probably give that a try.
 

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Titanium

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To determine if the feedhorn is centered, measure from several points around the reflector rim to the center of the feedhorn opening. If all measurements are equal, the feedhorn is centered. The simplest way to measure for centering is to punch a hole in the center of a throat cap, knot a string and pass through the hole. Insert the cap into the feedhorn throat. Use the length of the string to measure around the rim of the dish instead of fighting a measuring tape.

A laser pointer device will not determine if the feedhorn is centered on the reflector. The pointer device assists in making sure the feedhorn and scalar are pointed into the center of the reflector.
 

phlatwound

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To determine if the feedhorn is centered, measure from several points around the reflector rim to the center of the feedhorn opening. If all measurements are equal, the feedhorn is centered. The simplest way to measure for centering is to punch a hole in the center of a throat cap, knot a string and pass through the hole. Insert the cap into the feedhorn throat. Use the length of the string to measure around the rim of the dish instead of fighting a measuring tape...

Nice tip there Mr Ti...I will be using that one in the future. :hatsoff
 
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johnnynobody

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To determine if the feedhorn is centered, measure from several points around the reflector rim to the center of the feedhorn opening. If all measurements are equal, the feedhorn is centered. The simplest way to measure for centering is to punch a hole in the center of a throat cap, knot a string and pass through the hole. Insert the cap into the feedhorn throat. Use the length of the string to measure around the rim of the dish instead of fighting a measuring tape.

A laser pointer device will not determine if the feedhorn is centered on the reflector. The pointer device assists in making sure the feedhorn and scalar are pointed into the center of the reflector.

I was under the impression that if the laser dot hit the center of the base plate that meant that you're good to go. Anyway, I did the check as you suggessted to eight rim locations and the distances are with 1/4 inch of each other. I don't know if I can get it any closer or if it's worth the effort to get it closer.

I missed solar noon for today. Hopefully it won't be cloudy at solar noon tomorrow.
 
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johnnynobody

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Something looks a little funky?
The photo of your dish pointing straight up. Is your skew 0 reference on the lnb straight up too?

No. I adjusted the skew for maximum level and that's where it landed.
 

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johnnynobody

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That is indeed strange.. Either your true geographic south is not where you think it is (you might want to verify what the compass is saying with landmarks you can see and google maps). DO NOT rely on the compass in a phone. Or maybe the geometry of the dish is off. Did you do a string test? Also you might want to verify the centering of the feed with a tape measure, not just visually.

Attached are images of the string test. As you can see it's "perfect". See my reply to Titanium below about the feed centering.
 

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