I stretched strings N/S and E/W on my brand new dish. There is a 1/4" gap where the strings cross. Does this mean the dish is warped and if so how will this affect signal quality? Thanks.
Is my 90cm Geosatpro warped?
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Diy:
Is it installed? If not, assemble it and restring it. If it's assembled, try loosing all the fasteners and restring it. Could be the brackets or lack there of that's causing your problem.
If, after all your tests, you still suspect it being warped, go ahead and install it anyway and see what happens with signal strength and quality.
Believe it or not, the hot summer sun may actually be hot enough to "stress relieve" it back to it's proper shape. Used to know a welder who was a genius at straightening metal objects with the proper amount of heat applied to a specific location. He held a college degree in metallurgy and had a tremendous understanding of relieving stress in metal weldments.
Harold
Yes, it's already installed and I did not check for warping before I installed it. I did not overtighten the 4 bolts that hold the dish to the bracket. Just until very snug. Do you think I should tighten them until the nut stops?
I'd loosen the fasteners and see if it changes the string gap. If it's motorized, see if the string gap varies as the dish rotates East to West. Could the feed support be causing the warpage?
This is a tough one. The dish could have been malformed during manufacturing or damaged before you got it.
Harold
Signal Level & Quality
Here's my signal level and quality from the strongest transponder on each satellite. The skies were clear with no wind when I checked them. BTW, I'm using the Mercury II receiver and 85W is my true south satellite although I set up 87W as my true south sat for the motor.
I think some of them are pretty bad. Would the low quality result from a warped dish or misalignment or both?
Here's my signal level and quality from the strongest transponder on each satellite. The skies were clear with no wind when I checked them. BTW, I'm using the Mercury II receiver and 85W is my true south satellite although I set up 87W as my true south sat for the motor.
I think some of them are pretty bad. Would the low quality result from a warped dish or misalignment or both?
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Always check for warping that can occur during shipping. I have attached a PDF for correcting a warped reflector. A quarter inch gap on the string test will result in signal loss!
Thanks for the PDF file Brian. Can it be that simple? You got me scratching my head! I'm glad I don't currently have a warped dish to try this with, but I assure you, I will give it a try, if ever I need to.
Al
Al
OK I unmounted the dish and brought it inside and did the string test again. The strings touch each other where they intersect so it looks like the dish is NOT warped.
However when I put it back on the bracket with the nuts just barely screwed on to keep the dish from falling off the strings once again have a 1/4" gap where they intersect. I tightened the nuts down all the way but the quarter inch gap remains.
It looks like the dish is being warped when mounted and I'm still trying to figure it out.
Perhaps the bracket is warped............ any clues?
However when I put it back on the bracket with the nuts just barely screwed on to keep the dish from falling off the strings once again have a 1/4" gap where they intersect. I tightened the nuts down all the way but the quarter inch gap remains.
It looks like the dish is being warped when mounted and I'm still trying to figure it out.
Perhaps the bracket is warped............ any clues?
Diy:
If your brackets are oriented properly (my Fortec's have a specific orientation), then they must be malformed. Maybe you could leave them assembled to the strut and lay them on a flat surface to detect any missalignment and bend them correctly.
Did you measure with the dish pointing south or rotated to the East or West? It could be the feed support or a heavy LNBF that's causing the warpage as the dish rotates. It that's the case, you could use guy wires to help steady the support.
This is interesting, in that it illustrates how important every component of the dish is to it's overall performance. Even the lowly mounting bracket can distract from performance. It's been mentioned that the Fortec bracket angle markings are inaccurate. However, that's why it's important to make all angular adjustments using the signal meter to indicate the optimum setting.
Harold
I agree with caddata. Sounds like the Elevation Bracket is bent.
Was the Assembly Parts Box crushed in shipment or any indication that the 4 mounting points on the Elevation Bracket are twisted or skewed? The Elevation Bracket mounting points should lay perfectly flat on the back of the reflector and be aligned with the bolt holes.
Was the Assembly Parts Box crushed in shipment or any indication that the 4 mounting points on the Elevation Bracket are twisted or skewed? The Elevation Bracket mounting points should lay perfectly flat on the back of the reflector and be aligned with the bolt holes.
The assembly parts box was not crushed. I took the dish and bracket down and examined them. The bracket is shaped to fit the curvature of the dish and the four mounting points are flat. They don't seem to be twisted or skewed. With the dish face down I placed the bracket over the four holes. Everything lines up good and the bracket seems to fit well. So there's nothing wrong with the bracket that I can tell.
I did the string test again using several different variables. It was interesting to see that orienting one string over the other made a difference.
With the dish on the soft surface of a bed the string test showed a 1/4" gap either way the strings were oriented -- top-to-bottom string over the side-to-side string or side-to-side string over the top-to-bottom string.
With the dish on the solid surface of a table the test showed a 1/4" gap only in one string orientation -- top-to-bottom string over side-to-side string. The strings gently touched each other when the side-to-side string was over the top-to-bottom string.
I placed the dish face down on the dining room wooden table. It lies flat except the edge of one side seems to have about an 1/8" gap in a span of about 10 inches. Thinking that the wooden table may not be flat I gradually rotated the dish 360 degrees but the gap seemed to remain in the same 10" span as the dish was turned.
I flexed the dish by hold it like a steering wheel and thrusting it forward. I redid the above tests and did not notice any difference.
I turned the dish over with the reflector side facing up and picked it up about one foot off the table. I could see the dish bow as I raised it up. So this means the dish also bows when place on the soft surface of a bed -- thus the negative string test on the bed.
This also means that when the dish is mounted on the bracket on the pole it would also bow -- thus the negative string test when mounted.
I'm beginning to think that the dish is not warped but that the slight gap in the center of the 10" span on the edge of one of the sides is bent as a result of manufacturing.
Has anyone else done the string test with the dish mounted? What were your results?
I did the string test again using several different variables. It was interesting to see that orienting one string over the other made a difference.
With the dish on the soft surface of a bed the string test showed a 1/4" gap either way the strings were oriented -- top-to-bottom string over the side-to-side string or side-to-side string over the top-to-bottom string.
With the dish on the solid surface of a table the test showed a 1/4" gap only in one string orientation -- top-to-bottom string over side-to-side string. The strings gently touched each other when the side-to-side string was over the top-to-bottom string.
I placed the dish face down on the dining room wooden table. It lies flat except the edge of one side seems to have about an 1/8" gap in a span of about 10 inches. Thinking that the wooden table may not be flat I gradually rotated the dish 360 degrees but the gap seemed to remain in the same 10" span as the dish was turned.
I flexed the dish by hold it like a steering wheel and thrusting it forward. I redid the above tests and did not notice any difference.
I turned the dish over with the reflector side facing up and picked it up about one foot off the table. I could see the dish bow as I raised it up. So this means the dish also bows when place on the soft surface of a bed -- thus the negative string test on the bed.
This also means that when the dish is mounted on the bracket on the pole it would also bow -- thus the negative string test when mounted.
I'm beginning to think that the dish is not warped but that the slight gap in the center of the 10" span on the edge of one of the sides is bent as a result of manufacturing.
Has anyone else done the string test with the dish mounted? What were your results?
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Satellite AV ships several thousand of these dishes each month. We can assure you that this is not a manufacturing issue.
If all edges of the dish are not laying perfectly flat on a perfectly flat surface, the reflector parabola has been compromised. Sounds like the dish may have taken a hit during shipping resulting in one area being damaged.
If the dish has been delivered in the last 20 days and you have kept the packaging, we will be happy to facilitate a claim with FedEx.
Please contact our technical support department to facilitate this.
If all edges of the dish are not laying perfectly flat on a perfectly flat surface, the reflector parabola has been compromised. Sounds like the dish may have taken a hit during shipping resulting in one area being damaged.
If the dish has been delivered in the last 20 days and you have kept the packaging, we will be happy to facilitate a claim with FedEx.
Please contact our technical support department to facilitate this.
I have the Geosatpro 90 cm with the same problem. I worked around it by just finger tightening the bracket bolts to the dish. I have to snug them up from time to time but it works fine that way. If I put a wrench on them it warps the dish. The Bracket seems to fit the dish fine, not sure really what makes it go out of shape like that. I do know it is a very light, flimsy dish, mine weighs about 13 lbs as compared to my 100 cm wingard which is 29 lbs. I have had several dishes go out of shape when tightening up the bracket bolts, I thought it was pretty common? I've been thinking lately of trying a starchoice or primestar dish, it seems to me their ribbed design would maintain the parabola shape a lot better.
When we were looking for a manufacturer for our dishes, we tested many units and picked our partner based on the production accuracy, gauge of metal and excellent finish. The GEOSATpro 90cm is one of the heaviest metal dishes available with the reflector thickness measuring 0.7mm! Compare to some of the other popular dishes and you will see a noticeable difference in the thickness of the metal on both the reflector and the brackets. I agree with your observation that it is light-weight compared to a composite formed dish, but not comparing to other metal dishes!
While we take great care in designing a custom shipping carton to prevent shipping damage, the shipping gorillas sometimes take their toll on the merchandise! SatelliteAV stands behind our equipment 100%. If an item is damaged in shipment and you keep all packaging and notify us within 20 days of receipt, we will handle the shipping claim and advance ship the replacement item.
While we take great care in designing a custom shipping carton to prevent shipping damage, the shipping gorillas sometimes take their toll on the merchandise! SatelliteAV stands behind our equipment 100%. If an item is damaged in shipment and you keep all packaging and notify us within 20 days of receipt, we will handle the shipping claim and advance ship the replacement item.
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