Hughes Net Dish

[wvman]

I just happened to spot this dish at a local quick stop store and I was wondering if it could be used as a prime focus Ku Dish? It measures 38.75 inches across, but it's only 2.75 inches deep. I did the math and came up with a focal distance of 34.14 inches. It was previously used as a WV lottery dish.

I have an old Unimesh dish with tri-leg feed mounts that could easily be modified to make a prime focus feed mount. It has a round raised place in the center of the dish so focusing it woudn't be much of a problem. What do you think?



Here is the mount and feed arm assembly.

 

[primestar31]

Yep, it'll work fine. Just replace the transmit/receive stuff with a regular KU lnb.

 

[wvman]

Yep, it'll work fine. Just replace the transmit/receive stuff with a regular KU lnb.

None of the electronics out front of the dish was there, just the bare feed legs as pictured. It was originally set up as an offset feed, but without the original LNBF's, I have no way of knowing how to mount the new Ku LNB to get it at the right distance and angle.

I figured since it was round instead of eliptical, I could use it as a prime focus instead of an offset dish. Would it experience problems from adjacent satellites since it's so shallow?

 

[primestar31]

None of the electronics out front of the dish was there, just the bare feed legs as pictured. It was originally set up as an offset feed, but without the original LNBF's, I have no way of knowing how to mount the new Ku LNB to get it at the right distance and angle.

I figured since it was round instead of eliptical, I could use it as a prime focus instead of an offset dish. Would it experience problems from adjacent satellites since it's so shallow?

Don't try using it as prime focus, because there's not enough area there to do that. Just aim it at a known satellite, and use some EMT hangers, nuts and long bolts from Lowes or Home Depot. That way you can adjust them up and down until they seem to work well.

Or you could just find a person that has one of these already, and knock on the door and ask him if you can take some measurements from his dish and lnb setup.

There's also offset dish calculators out there that can help, but I've always found them fairly complicated, if you have another way to get the info.

 

[wvman]

Don't try using it as prime focus, because there's not enough area there to do that. Just aim it at a known satellite, and use some EMT hangers, nuts and long bolts from Lowes or Home Depot. That way you can adjust them up and down until they seem to work well.

Or you could just find a person that has one of these already, and knock on the door and ask him if you can take some measurements from his dish and lnb setup.

There's also offset dish calculators out there that can help, but I've always found them fairly complicated, if you have another way to get the info.

Is the off set angles for these dishes figured into the elevation marks on the mount?

 

[primestar31]

Is the off set angles for these dishes figured into the elevation marks on the mount?

Normally, yes. I don't know about that particular HN dish, BUT, it's very likely to be somewhere in the range of 22 to 27degrees of offset.

Check this thread, (post 7) as the dish looks like yours: Hughes HN7000S Dish Alignment Help

 

[a33]

Is the off set angles for these dishes figured into the elevation marks on the mount?

Yes, if you install the dish face exactly plumb/vertical, the elevation scale reading should be the offset angle (assuming the scale is precise; it usually is not very precise, however...)
Otherwise for the offset calculation, you'd need hight and width of flat effective reflective dish area. The 'water-method' could help there. But this only applies when the dish is purely paraboloid (parabolic in three dimensions).
When the dish is meant for multifeed (parabolic vertically, and circular (spherical) horizontally), you'd need the deepest point measures. To find the exact spot of deepest point I find very hard, however. Might be somewhere in the middle between the mount bolts; but even with a marble (or tracker ball of computer mouse) I did not get very precise measurements for that.
I've been thinking of a way to measure and calculate multifeed dishes, but that is still in the concept phase.....

Does the dish have a non-flat face? Or why is it round (rim of defferent hights?), when it is supposedly an offset dish?

Don't use Parabola calculator 2.0 for offset focal point calculations; it gives incorrect results.
Parabola6 is good, however uses only 'depth at the middle'-measurements.
My own calculator uses triangle top of dish -- middle of dish -- bottom of dish measurements as inputs in method D (with offset angle already known), I find that easier and more accurate than method E (the Parabola6-method).
See attached picture to get an impression of the 7 methods (with different inputs needed) for parabolic satellite dish calculations, that I use in my calculator. (Method D is my favorite. Method F is very good for quick and dirty, when the feedhorn position is already known.)



Greetz,
A33

 

[wvman]

Yes, if you install the dish face exactly plumb/vertical, the elevation scale reading should be the offset angle (assuming the scale is precise; it usually is not very precise, however...)
Otherwise for the offset calculation, you'd need hight and width of flat effective reflective dish area. The 'water-method' could help there. But this only applies when the dish is purely paraboloid (parabolic in three dimensions).
When the dish is meant for multifeed (parabolic vertically, and circular (spherical) horizontally), you'd need the deepest point measures. To find the exact spot of deepest point I find very hard, however. Might be somewhere in the middle between the mount bolts; but even with a marble (or tracker ball of computer mouse) I did not get very precise measurements for that.
I've been thinking of a way to measure and calculate multifeed dishes, but that is still in the concept phase.....

Does the dish have a non-flat face? Or why is it round (rim of defferent hights?), when it is supposedly an offset dish?

Don't use Parabola calculator 2.0 for offset focal point calculations; it gives incorrect results.
Parabola6 is good, however uses only 'depth at the middle'-measurements.
My own calculator uses triangle top of dish -- middle of dish -- bottom of dish measurements as inputs in method D (with offset angle already known), I find that easier and more accurate that method E (the Parabola6-method).
See attached picture to get an impression of the 7 methods (with different inputs needed) for parabolic satellite dish calculations, that I use in my calculator. (Method D is my favorite. Method F is very good for quick and dirty.)

View attachment 136832

Greetz,
A33

Using a drywall square, I laid it across the surface of the dish in 4 positions 90 Degrees apart. I went to the 8 inch mark on the square and measured to the dish surface. I did that in 4 different places, then I moved to the 16 inch mark and repeated the process, and did the same with the center. Each of the distances from the square to the dish at each point was the same all the way around.

It indicated that the dish is not eliptical in shape. That's why I was wondering if it could be used as a prime focus dish rather than an offset. Other than being 2.75 inches deep and 38.75 diameter, it's design appears to be no different than a standard C-Band design. Having said that, the mount does NOT attach to the dish in the middle, which would make it difficult to motorize, but I'm not interested in doing that anyway,

 

[wvman]

Normally, yes. I don't know about that particular HN dish, BUT, it's very likely to be somewhere in the range of 22 to 27degrees of offset.

Check this thread, (post 7) as the dish looks like yours: Hughes HN7000S Dish Alignment Help

I have the original feed supports on the dish now, but since none of the electronics were on the dish, I have no way to figure out where the LNBF needs to mount on the center feed support or where the focal point is in the new LNBF. I looked that dish up on DSL Reports and it showed all the electronics on it and the feed throat is much further down the feed bracket than I expected it to be.

There are two tags on the back of the reflector, but the writing is long gone. I may have to do some trial and error to find the sweet spot.

 

[wvman]

Yes, if you install the dish face exactly plumb/vertical, the elevation scale reading should be the offset angle (assuming the scale is precise; it usually is not very precise, however...)
Otherwise for the offset calculation, you'd need hight and width of flat effective reflective dish area. The 'water-method' could help there. But this only applies when the dish is purely paraboloid (parabolic in three dimensions).
When the dish is meant for multifeed (parabolic vertically, and circular (spherical) horizontally), you'd need the deepest point measures. To find the exact spot of deepest point I find very hard, however. Might be somewhere in the middle between the mount bolts; but even with a marble (or tracker ball of computer mouse) I did not get very precise measurements for that.
I've been thinking of a way to measure and calculate multifeed dishes, but that is still in the concept phase.....

Does the dish have a non-flat face? Or why is it round (rim of defferent hights?), when it is supposedly an offset dish?

Don't use Parabola calculator 2.0 for offset focal point calculations; it gives incorrect results.
Parabola6 is good, however uses only 'depth at the middle'-measurements.
My own calculator uses triangle top of dish -- middle of dish -- bottom of dish measurements as inputs in method D (with offset angle already known), I find that easier and more accurate than method E (the Parabola6-method).
See attached picture to get an impression of the 7 methods (with different inputs needed) for parabolic satellite dish calculations, that I use in my calculator. (Method D is my favorite. Method F is very good for quick and dirty, when the feedhorn position is already known.)

View attachment 136832

Greetz,
A33

I spent considerable time straightening the feed supports. Whomever it was that took it down didn't take much care to avoid damage to the supports or refelector. Luckily, the damage was confined to the feed supports and not the dish. Here's a photo of where I'm at on it at this point.


Spent considerable time straightening the feed arms and used the plastic trim piece to secure the LNBF to the feed arm. I think once I get it outside and on a pole, it should be relatively simple to locate the focal point and get a signal. (Hopefully) Weather here is horrible, so that will be a project for another day.

Once I get the sweet spot located, I can bolt the plastic piece to the arm and remove the hose clamp and do the fine adjustments.

 

[comfortably_numb]

I spent considerable time straightening the feed supports. Whomever it was that took it down didn't take much care to avoid damage to the supports or refelector. Luckily, the damage was confined to the feed supports and not the dish. Here's a photo of where I'm at on it at this point.
View attachment 136844

Spent considerable time straightening the feed arms and used the plastic trim piece to secure the LNBF to the feed arm. I think once I get it outside and on a pole, it should be relatively simple to locate the focal point and get a signal. (Hopefully) Weather here is horrible, so that will be a project for another day.

Will be curious to hear your results

 

[wvman]

Will be curious to hear your results

I'll post them when I finish this project.

 

[primestar31]

I'll post them when I finish this project.

Fine tune the lnb on a WEAK signal, not a strong one! Also for obvious reasons, do NOT use a PLL type lnb to do this. You need one that doesn't track and hold onto signals pretty much no matter what, like a pll one would.

 

[wave catcher]

I'll post them when I finish this project.

I have 2 of dishes like that. Use the old LNB to position the new one then fine tune it on a known signal. They are made for only 1 LNB and make a great FTA dish.

 

[comfortably_numb]

I have 2 of dishes like that. Use the old LNB to position the new one then fine tune it on a known signal. They are made for only 1 LNB and make a great FTA dish.

He said he doesn't have the old LNB...

 

[wave catcher]

He said he doesn't have the old LNB...

I have one of those Hughes Net dishes, it works very well, good quality dish. But you must find the exact focus point and offset angle. Use 8 little square mirrors, one inch square or aluminum foil squares Attach mirrors to the dish in cross pattern (vertical and horizontal) but not near the middle with 2 mirrors on each leg of the cross. Point dish at the sun, use a piece of card stock paper moving it in and out to see the best focus point, and move dish left, right, up, down, to see where the reflected lights converge in the tightest pattern. Set LNB at that point. Also make sure LNB is pointing straight at the center of the dish. This cannot be done indoors with some bright light, this only works using the sun.

 

[wvman]

I have one of those Hughes Net dishes, it works very well, good quality dish. But you must find the exact focus point and offset angle. Use 8 little square mirrors, one inch square or aluminum foil squares Attach mirrors to the dish in cross pattern (vertical and horizontal) but not near the middle with 2 mirrors on each leg of the cross. Point dish at the sun, use a piece of card stock paper moving it in and out to see the best focus point, and move dish left, right, up, down, to see where the reflected lights converge in the tightest pattern. Set LNB at that point. Also make sure LNB is pointing straight at the center of the dish. This cannot be done indoors with some bright light, this only works using the sun.

Sounds like a good idea. I can see where that would work really well. We get so much rain here in the spring, it might take an act of God to use that method.

 

[wvman]

He said he doesn't have the old LNB...

True, all I got was the bare dish. I guess the lottery commission installer took all the electronics when they changed out the dish.

 

[wvman]

Fine tune the lnb on a WEAK signal, not a strong one! Also for obvious reasons, do NOT use a PLL type lnb to do this. You need one that doesn't track and hold onto signals pretty much no matter what, like a pll one would.

Here's the LNBF I have for it. "Geosatpro SL1-PLL Standard Ku LNB." Ordered it from Hypermegasat. If there's a better choice for tuning it, I'm up for suggestions. I need to look to see what the Lo Frequency is to set it properly at the receiver. I'm going to try and use this meter to locate the signal and fine tune it.


It processes the raw signal, but it won't decode the video or audio. I've used it to peak the signal on several FTA dishes. So far, it's worked well on C-Band and Ku. I used it a lot when I was installing Dish & DirecTV.

 

[a33]

We get so much rain here in the spring, it might take an act of God to use that method.

Measuring and putting the data into a calculator will be as good, assuming that it realy is a parabolic mirror. Can be done anywhere.
If it's not a parabolic form, then the mirror method might be best.

BTW. An LNB on an offset dish should be aimed lower than the middle of the dish, somewhere between the deepest point of the dish and the half-subtended angle point for the LNB (G-spot). Deepest point has highest beam density I believe I read, and G-spot has least spil-over; so somewhere between those two seems to be a good compromise.

greetz,
A33