TV4RV AUGUST NEWSLETTER

Vol. 3 - No. 8

COMPASS DEVIATION

When setting up and aiming a satellite dish three settings are very important to finding the satellite target - azimuth, elevation and skew / tilt.  If you have a plumb mast on your tripod, the elevation and skew / tilt settings should be fairly close to the markings stamped into the frame of the satellite dish, with just a little tweaking to max the signal.The azimuth setting is not quite so predictable as it requires using a compass to find the correct heading.  If there is no outside interference with the compass reading, then this setting is pretty straight forward when using our eZee-Aim%uFFFD system.  Just point the tripod, install the dish and you are almost right on target.However, there are often outside influences, either natural or man-made, that can and will effect the needle of the compass to pull it away from pointing directly at magnetic North.  These influences can be the steel in your RV or tow vehicle that might be parked nearby, metal fencing around the site, high tension electrical wires overhead, even ore deposits underground.  All of these things, and more, can deflect the compass needle as much as 20 to 25 degrees.In preparing this article I performed a small experiment to see if I could find a way around this problem by shielding the compass from the source of interference.  I held a small pocket magnet about 10" from the compass to pull the compass needle off the mark.   Then I inserted a heavy aluminum griddle between the magnet and the compass to see if I could block the magnetic field.  The test failed.  Magnetic fields do not travel in a straight line.  Instead, they form a "field" around the objects the are effecting.  I would need to encase the compass completely within a box to have the effect I want, but that is not a viable solution.It would seem there is no easy solution to this problem. Try to stay far away from objects that can effect the compass when setting up the tripod.  Just being aware that it can happen will make it less frustrating when you aim the dish and there is no signal.  On those occasions, be prepared to swing the dish both left and right, maintaining the correct elevation, until you hit the signal.