Tips / Tricks for Adjusting Azimuth to True South?

[IA6Newspath]

As an important step in aligning a motorized Ku dish is initially setting the azimuth to true south, I'm curious if anyone has any tips or tricks for hitting the true south mark when aligning a motorized Ku dish. Obviously, having a compass is a good place to start, but it seems to me that unless the compass is somehow securely mounted to the motor/dish assembly, there would be a fairly significant margin of error by simply eyeballing the dish/motor assembly's azimuth based only on comparing its direction to that of the compass needle (not to mention taking into account magnetic declination as well). That said, are there any tricks or particular compasses or gadgets that ease the process of accurately setting the initial azimuth to true south?

 

[tom_v]

- Compass is still the best tool. However, to have an accurate read of a compass, it must not be sat too close to the pole, dish, or any metallic materials. Use a long piece of wood (stick) to point to the TS according to the compass, then set the whole motorized dish sytem toward that...

 

[sdoradus]

Im pretty sure that I am the oddball on this forum since I don't follow any of the usually recommended steps for dish alignment. In any case here are the steps I use that give me a true south alignment for an offset lnb type dish.

1) Carefully draw a north south centerline on the surface of the dish. Usually there are tooling or molding marks on a dish to do this accurately.
2) Stretch a string tightly across the dish between the end points of same centerline (curve of dish will have string setting several inches above the surface at dish center similar to a bow).
3) Use a starcalc program or similar method to determine what time the sun will cross your true south position based on your longitude.
4) When the time comes make sure your motor is set at zero and a simple alignment of the shadow of the string with the drawn centerline should put everything at dead on south.

For C band larger dishes with lnb center mount one can use the same general idea. Both of my 10 ft dishes are sectional that bolt together along the north side line so I just have to align the shadow of the feedhorn with the section line at the proper time. After over 50 years of aligning polar mounts for my telescopes this was the easiest and most accurate method for my satellite dishes without having to deal with the innacuracy of a compass and its various deviations based on location.

SD

 

[Greg Mueller]

In the astronomy hobby, aligning the "polar axis" to true north is a must for good tracking. To find true north you can align on "the pole star" or "Polaris". Even that is not exactly true north but it's pretty close and you can fine tune from there.

Everyone knows what "The Big Dipper" looks like. If you take the two stars that make up the dipper part, that are opposite the handle, and draw a line through them and extend it up (away) from the bowl, the first bright star you come to is Polaris.
You can go out at night and find Polaris and site from your pole to Polaris. Then put a stick in the ground (or use a landmark) some distance off. Then during the day you will have a good idea as to where true north is. True south would be the opposite direction.
Hope this helps

 

[PSB]

I would use your true south satellite to find your zenith position, a compass will just get you in the ball park!

If you have USALS any satellite close to the top of the arc will work!

 

[charlie123]

true south

I have a crude method that worked for me.

I was tired of the compass getting interference of all the metal in the dish. Went to Lowes picked up a straight 6' piece of wood and put this horizontally across the dish with the compass on the very end. As long as the reading on the compass across the wood as the true south -90 degrees it was close. Moved the dish with the motor to IA5 during this process I saw the signal strength on the receiver (pansat 2700) spike during the movement and go down. Knew at that time I surpassed the satellite moved the dish back by hand until I had a good signal.

 

[PSB]

Now that IS a good idea

 

[Tron]

I never worry much about azimuth, since if you have your elevation correctly set, you can find correct azimuth by panning the dish or dish/motor assembly. If there are any DirecTV or Dish Network dishes in the neighborhood, you don't even need a compass to know generally where everything is.

Whenever I travel, I make a note of where dishes are pointed. I know of a BUD that is pointed toward the northeast, and I'm getting ready to ask the property owner for it since I'm sure he's not using it

 

[IA6Newspath]

Thanks for all of the suggestions. While I'm sure peaking on a true south satellite is a much easier way of adjusting azimuth than using a compass, I really don't have a true south satellite as my latitude is almost exactly 86 deg. W, so I'm right between AMC 2 (which has little if any FTA digital activity anyway) and AMC 3. That said, even if I were to peak on either of those two, my true south would still be off by a degree or so, and I'm sure this would be problematic for a motorized dish setup.

 

[SATisfied]

Well, I'll chip in my two cents on the subject. I tied a string around the mast just below the dish with the dish facing south. I set my compass to 191 which was my true south setting. I pulled the string taught while facing the dish and aligned my compass with the string and just swung it around until the needle was inside the arrow. I moved the dish accordingly until it was facing true south. It worked like a charm. Make sure the string on the mast is dead center to the dish, lnb, and mast.

I guess you've learned by now that if you get the compass too close to anything metal, it goes haywire. With this method, you can get the compass away from any interference.

 

[charlie123]

true south

The method I described I used to determine the true south from my location. After I did this I used the receiver to move the motor by selecting the satellite. In your case you could chose AMC3. By doing this and if you get a good signal, or slightly adjusting the dish you will also adjust the reference point (true south). If you were to move the dish back to the reference point (from the receiver install menu) after finetuning on let's say AMC3 then you have also improved your setting for the true south.

 

[Tron]

I really don't have a true south satellite as my latitude is almost exactly 86 deg. W, so I'm right between AMC 2 (which has little if any FTA digital activity anyway) and AMC 3. That said, even if I were to peak on either of those two, my true south would still be off by a degree or so, and I'm sure this would be problematic for a motorized dish setup.

You can use USALS instead of DiSEqC 1.2 to move your dish to one of those two satellites before you peak the azimuth. The motor should only move a tiny bit from its '0' position. Then you can peak your signal with the motor properly positioned. I always use USALS for motor installation, its really much easier.