Have you ever not been able to get a dish to work? (1 Viewer)

N6BY

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My 8.5' Birdview dish served me well for 4 1/2 years.

A couple of months ago I had to move the dish out of the way because we were having a patio installed. I bolted the pedestal base to a 4x4' sheet of plywood and it didn't take me long to get it realigned to the arc. All was well.

Then two things happened: 1) The patio was installed, and 2) We had a major windstorm that blew the dish way out of alignment. I didn't have the bolts locked down tight enough.

Now, no matter what I do, I cannot get the signal above about 2.5 dB for KU band (as seen by my TBS6983 running EBSPro). In the past I have been able to get the dish lined up to the arc without much trouble. I have spent a few hours now without success.

Here is what I have tried:
1) Switched RG6 cables.
2) Switched from an Invacom to an Inverto LNBF
3) A different receiver
4) Measured the dish for warp (it checked out OK with the string test)

The line of sight is clear. My yard sits high above the oak trees to the south.

I don't have another KU dish to try. I used to have a GeosatPro 1.2 meter dish that warped. I would get another, but I am reluctant to spend $179 on another dish that might warp.

Any suggestions?
 

N6BY

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The base is bolted on a 4 ft x 4 ft sheet of plywood held down by about 400 pounds of concrete blocks. Before the patio was installed and the windstorm, it worked fine on the plywood base.

So the base is not the problem. The problem is that I cannot get the signal above 2.5 dB for any transponder on any satellite. I have tried adjusting the aim for several hours without success.
 

primestar31

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Have you taken your receiver or sat meter right to the dish, and used a new short piece of coax with NO switches inline for a test?

I've never had a Birdview dish, but don't they have built-in HH motor drive? Perhaps your large windstorm torqued the mount in some way, so that declination or the mount itself is out of whack in some way that's not obvious?
 

N6BY

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I don't have any switches, and I did try a short coax run. It does have a built-in HH motor drive.

The problem is that I can't get a usable signal on any satellite, even with manual aiming and adjusting 1/10 of a degree at a time. Something is wrong and I can't figure out what it is.

Also, I have checked the focal distance and the skew. They are both good.

I am thinking about ordering one of these: C Band 120cm (4 feet) Prime focus dish antenna /satellite dish | eBay
 

primestar31

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Did you check to make sure the feedhorn is still centered, parallel to the dish surface, and at proper distance?

It just doesn't make sense. It would have to be something fairly obvious that's just being overlooked somehow.
 

N6BY

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The feedhorn is mounted on a 1/2" PVC sheet which cannot move. It's parallel to the dish surface.

I agree that this makes no sense at all. I have aimed dishes for many years without problems. The only time I ever had a problem like this was when the 1.2 meter GeosatPro dish warped.

I'm wondering if the wind damaged the dish in a way that I cannot see? I tested it with 2 taut wires and they touched. Maybe I need to try more wires in different places?
 

KE4EST

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Maybe I need to try more wires in different places?
This.
I had a dish with the same issue. About drove me to run to the bar and get drunk. Till I decided to check again for warp-age. Put strings a different place and aha!!
 
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N6BY

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This.
I had a dish with the same issue. About drove me to run to the bar and get drunk. Till I decided to check again for warp-age. Put strings a different place and aha!!
I'll unbolt the reflector tomorrow and see what it looks like on a flat surface.

Will probably need to find a new dish .......
 
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Cosmo Blatz

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Have you ever not been able to get a dish to work?

Yeah, this one. LOL!

dish1.jpg
 

primestar31

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This.
I had a dish with the same issue. About drove me to run to the bar and get drunk. Till I decided to check again for warp-age. Put strings a different place and aha!!

Yeah, I'd agree. The dish itself must be torqued somehow, if you are sure you ruled out everything else already. As for another dish, I'd really lean towards finding a restorable old-school dish, before I'd go for a China new one. There's still plenty out there, especially when you start looking for them. I find them on Facebook Marketplace for "come and take it away" prices all the time, though it tends to boom and bust at times.

Most old dishes are built better then the Chinese ones, you get the joy of saving a lot of money over a new purchase, and saving it from the scrapper along with the fun of rehabbing it.
 

N6BY

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I have an excess 8' Odem brand, solid perforated reflector with feed support arms that I will not be using. In good shape and stored at my shop. Yours free for the hauling. :)
Thanks! Will it work for KU band or are the holes too big? Also, it it one piece or sectioned?
 

N6BY

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I just got back from visiting Brian and picking up the dish. It was about 20' outside his office door but it blended in with the asphalt so well I didn't even see it on the way in! We chatted for a while and then he got the dish tied on to my truck's bed, on top of a wood frame that I brought to support the edges. When he was done it was so well secured that if you touched the dish the whole truck bed would move with it!


BrettTruckAndDish.jpg



After we got the dish loaded up we came back into the office and Brian gave me a quick demo of the OS Mio+ and blind scanning 99W. I like all the options it has for blind scanning, and it will be a perfect replacement for my U4 Quad with a broken remote. It has a very nice, metal remote which looks 'Brett proof'. (I managed to break my cheap plastic U4 Quad remote). Will order a Mio+ after I get the new dish setup.

BrianInOffice.jpg


With a very wide load on my truck I started to get really nervous when it was time to leave. But rush hour was near and I had to go. I had about a 25 minute drive (mostly freeway) ahead of me. My worst fear was that I would hit a car in the next lane and somehow cause a multi-car pileup. (I worry too much).

But I had no problems at all on the way home. I stayed in the right lane as much as possible and tended toward the right of center when there was a shoulder.

The dish is much lighter than the Birdview it will replace. From my driveway I was able to 'turtle-back' it into the backyard by myself. Wish I had a photo of me and the dish shell (the giant turtle with only 2 legs) but no one was here to take it.

Below is the dish and equipment on my new patio, not far from where I will set it up. It lies perfectly flat on the patio and appears to be in excellent shape. It's 1/8" holes serve to make it light enough to manage and it will still be fine for KU band.

NewAndOldDishes.jpg


The dish will be easy to bolt onto my existing Birdview H-H motor. Below is the dish's original motor (which Brian is keeping for future use).

AMCI_Motor.jpg


Anyway, I am very happy to have an excellent replacement for my warped Birdview dish. When I started this thread I never imagined that it would happen so quickly.

Again, thank you very much Brian. I will post photos when I get the dish mounted and working.
 

N6BY

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Today I removed the Birdview reflector from the motor base. I tested it with two tight wires at 90 degrees (in different places than before) and they were about 1/4" apart at center. 1/4" difference from a perfect parabola is too much for KU. At around 12 GHz the wavelength is about 1 inch. After reflection the 1/4" surface difference becomes 1/2" distance traveled to the LNBF. That's enough to cancel out a large portion of the signal reaching the LNBF.

The Birdview dish is quite sturdy. Its hard to imagine the force required to bend it. But I live on a hill which does get a lot of wind.

Before I moved the dish out of the way for the new patio it was in an area shielded by the house from the wind. But on October 23rd it was fully exposed to the wind. That's when there were extremely high winds in the central valley here and P.G.&E. turned off the power to thousands of Northern California customers as a precaution.

The Birdview dish has a radius of 8 1/2 feet, or a total surface area of 227 square feet. Wind produces a force per square foot of 0.00256 * wind speed squared. For a 50 MPH wind, the total force on the Birdview dish was 227*0.00256*50^2 or 1453 pounds!!! And the wind was gusty, so the force repeated over and over for several hours. I can now understand how that much force, repeated over and over, would bend a large piece of aluminum.

So the lesson I learned (the hard way) is to always keep the new dish in a wind protected area. I will move the dish base back to where it was before, protected from the wind. I just need to drill 4 new holes in the Birdview motor base mount and will be able to bolt on the new dish. I hope to have it done within a few days.
 
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