Installation Questions

[Pviscomi]

I have had a motorized dish for over a year now. It is working well. Lately, I have been scanning other sats just playing around and I noticed that the eastern side my dish is too low, possible being impaired by the roof itself. So I was thinking of raising it without using a tripod. I already have the tallest mount, so I have been thinking of making my own. Anybody ever done that? Any ideas, hints help would be more than welcome. Also, I was reading the info on the mounts and one line caught my eye:"Make sure the slanted roof is facing South." My roof slant faces east. So what are the implications of that? Thanks

[pmb1010]

I think that is the suggestion, because of the length of the support brackets. If you put this on the other side of the roof (ie: north side) the brackets would to be long enough to make the pipe vertical.

And that is the key. Whatever you do, the bottom line is the pipe that the motor mounts to must be plumb in all directions.

Other than that, anything sturdy that can hold up to wind load of a 30 inch disk will suffice.

[wejones]

While I agree that it makes alignment MUCH MUCH easier, it isn't necessary that the pole be plumb. There used to be a fellow on the web who had demonstrated how to align a polar mount on a pole that was sloping something like 40 deg. I didn't beleive it at the time, so I made a little wooden model of a dish on a polar mount intending to prove that it wasn't possible, but I ended up proving that it WAS possible. A non-plumb pole sure makes it hard, however, so it's highly recommended to make sure that the pole is plumb. Re the slope of the roof, I think that would only affect how high the pole needed to be, so as not to bump into the roof.

[pmb1010]

I thought about this for a while.
I can see if you were at the equator, and the pole was tilted parallel to the equator, shifting side to side it would still track the arc.

but if it was north or south tilted, I dont see how you could compensate for that...

[wejones]

I thought about this for a while.
I can see if you were at the equator, and the pole was tilted parallel to the equator, shifting side to side it would still track the arc.

but if it was north or south tilted, I dont see how you could compensate for that...

Yeah, I thought pretty much along the same line. I could easily see how you could make up for tilt to your south or north, just by increasing or decreasing the motor elevation, but it wasn't obvious how to compensate for tilt say to the southwest or something. However basically, all you're trying to do is get the motor's axis to be nearly pointing toward the north star. It turns out that by a combination of changes to the motor elevation and rotating the whole mount on the pole, that you can always bring the aim of the motor's rotation axis back toward the north star. If for example, the tilt is to the southwest, the axis would be pointing a bit high and west. If you rotate the mount clockwise on the pole, it will bring the axis back to pointing north, but it will be too high or low, but if you then alter the elevation to correct that, it will be the right elevation, but not pointing north anymore. But after a few back and forth adjustments, you can hone in on the proper aim. A fellow, who's name I forget used to sell a gadget called Arc-Set or something (I have one, but I'm too lazy to go look), which is a magnetic adjustable triple level, ie 3 levels in one. With a big dish with good surfaces related to the motor axis, dish aim, and a compass for true south, you could quickly align a dish even on a tilted pole. I did it on my tree mounted dish several months ago, although it's alignment didn't last long, since the tree was still growing. But basically, just hold the one level on a surface parallel to the motor axis, and change the elevation and rotate on pole until the level indicates right while aiming north.
On a small dish, it would be harder to do, and USALS wouldn't work unless you reset the motor's zero, but you could get it to track.

[rainman]

sounds like alot of trouble when its not that hard to set your pole plumb in the beginning.

[wejones]

sounds like alot of trouble when its not that hard to set your pole plumb in the beginning.

Yep. I think the only time I'd consider it worth the trouble is if you already had a pole set in concrete, and it somehow got tilted. That Arc-Set thing makes it easy though, at least for a big dish. The fellow (I think he called his company Gormet Entertainment or something like that) set the three levels specifically for your latitude so that you just go outside and make a few adjustments to get the levels on the mark, and you're in alignment. People used to swear by it on the web. I didn't buy mine from him, but instead got one used, so it wasn't set properly for my location, but I calibrated mine using my already aligned dish, then took it over to another dish, and dialed it right in. All I had to do was rotate on pole for true south to get reception.

But yes, it's much easier to make the pole plumb in the first place.

[pmb1010]

ARC-SETs


An ARC-SET is a truly miraculous device! It will put any "Polar" mounted, parabolic Dish, precisely onto the ARC, in a matter of minutes, without reliance on a compass, and without the post having to be plumb! It is an exacting Analog Computer, using ever-present gravity and a single Satellite's signal strength, to get you home in time for dinner. It is sufficiently accurate for unforgiving Ku-Band birds! The ARC-SET is used as follows:
Place your ARC-SET on the Axis of your Mount, and adjust the elevation setting of your Mount to center that bubble marked AXIS. The Axis is the line between the pivot points on which your Dish will be turning as it is actuated through the Satellites. Where you physically put your ARC-SET depends on the variety and design of mount mechanisms which you encounter. The AXIS inclination is the same for all "Polar" Mounts, even under spoon dishes. On some totally enclosed horizon-to-horizon drives, the Axis is buried inaccessibly inside the machanism, but you can expose the semi-circular gear and use your ARC-SET's ends (which are exactly perpendicular to its magnetized edges) against the gear's face.

After having first set the AXIS elevation, transfer your ARC-SET to your Dish, perpendicular to its parabolic axis (your Dish's "look direction"). If it is a parabolic Dish, your ARC-SET will be parallel to the lip-to-lip slope of the Dish face. If it is a Spoon Dish, its real look direction will not be perpendicular to the lip-to-lip slope of the face. Usually, some surface on the back of the Dish is available to provide reference. Failing that, you can always use the lip-to-lip slope across the face of your Dish. Your ARC-SET is now above the Declination adjustment, and you use the Declination adjustment to center your ZENITH bubble. This is done with the Dish swung (actuated) up to its highest look angle (its Zenith) -- as if looking South. Your ARC-SET will be on the Dish, parallel to the line of the Mount's Axis. Your Declination (aka Off-Set Angle) equals: ZENITH - AXIS.

Now comes the fun (miraculous!) part: lower the dish, by its actuator to the side with your lowest active Satellite. The Satellite can be partially obstructed(the picture does not have to be "watchable" for your client -- just sufficiently detectable to tell you and your CANARY when/where you have peaked its signal). As you actuate the Dish toward that side, you can use the same slope reference surface as for the ZENITH, but you must turn your ARC-SET to follow the Dish's steepening slope. Turning (like a wind-shield wiper) to center the little bubbles, in the end of the EXTREME & ZENITH sections, guides you to the slope's steepest angle. Actuate the Dish down until its steepest slope centers the EXTREME bubble. This gives your Dish the appropriate look angle for the Satellite. Then twist the Dish in azimuth (around its ground pipe) to peak up that Satellite's signal. This orients the Axis to True North/South (better than a compass) and brings your System's actuation track onto the Arc!

If the pst is not plumb, that is no major problem! All that you need do is move the actuator sufficent to keep the EXTREME bubble in the center as you turn the dish in azmuth. That will guide you to the Satellite. Then, while you are still on that Satellite, go back and readjust the mount's axis inclination (which will have changed as you turned around on a non-plumb post) to center the AXIS bubble. Don't change the Declination! Your ARC-SET keeps you from getting lost. If you happen to lose the Satellite's signal, the centered EXTREME bubble will guide you right back to it. Once you have the AXIS bubble centered, on the mount's axis, the EXTREME bubble is centered on the dish's inclination, and the signal from the extreme satellite is peaked, you are on Arc -- no matter where the support for the dish comes from.
As a check, actuate all the way over to the opposite-from-extreme Satellite and, while while watching Signal Strength (with your CANARY), gently lift (and then pull down on) the lowest part of the Dish Lip. If the Signal increases either way, you have mis-measured -- or the Feed is off-center Actuate up to ZENITH and double check the Dish slope (including front lip-to-lip) to confirm the bubble centers. Guy wire from highest, to lowest points of Dish lip, and pull the Feed to the spot of highest Signal Strength. Then actuate down to EXTREME and double check the Dish slope to confirm that bubble centers. Guy wire between what are now the highest, and lowest points of Dish lip, and pull the Feed to maximize Signal. This forces the Feed into the "sweet spot" of the Focal Cloud.
The ARC-SET comes apart into two, or three, of its component sections, for mount designs that are too tight to fit the entire ARC-SET into their configuration -- or for simultaneously watching the AXIS and EXTREME bubbles as you trim a system on a non-plumb post. It comes apart with 1/4 X 20 nuts and bolts. They are just the size which you use to secure LNAs to feed, etc. -- so if you ever need spares to finish up a job right, without going all the way back, you can borrow them from your ARC-SET. (It's sort of like always having water-proof matches). ARC-SETs are cast of virtually indestructable Poly-Carbonate, and have very strong (up to 7-G's) magnets along both edges.
The ARC-SET's transparent body allows you to see the bubbles from virtually any vantage point (for alignment of Dishes which are in creatively inconvenient locations). There are transverse bubble vials fixed in each end to guide you in measuring the steepest slope angle of any inclined surface. Your ARC-SET can be pre-set for your 50-mile territory, based on our computer's "Optimum 'Polar' Mount Analysis". You can easily re-set it for alternative locations. Loosen the slotted screws to change its settings. With the screws loosened, the adjustable level vials turn easily. Put your ARC-SET on a trustworthy "Mother Dish", in the alternative location, that is satisfactorily on ARC (with its Feed properly laterally focused), center the AXIS, then ZENITH, and finally the EXTREME bubbles, and tighten the slotted screws (they go metal to matal, to lock the bubbles firmly without risk of pulling out threads). Your ARC-SET will duplicate that "Mother Dish" exactly and within a 50-mile radius, it will put all the new Dishes on the Arc just like it. Be sure to set it back, from one of your previously set local Dishes, when you return home.

[wejones]

Yep, that's the device I have. The fellow that makes them used to post a lot on Homesat / Rec.video.satellite/tvro .

Unfortunately, really only easy to use on a prime focus dish, but it's a neat gadget.

I didn't know that he was still in business.

[pmb1010]

it was on an old link still running on a 4dtv website.
Some of your stuff is there, too. About aligning a dish.

I thought it would be interesting reading for anyone curious about this thread.

What got me interested, originally about this -- was an item I saw about the sucess of moving the "true south" sat away from the high point for a users location. The premis was to adjust the arc to the left or right, so that lower sats could be achieved with H-H motor that was limited in range.