Anyone have a link to an accurate elevation / declination chart for cband? I've seen a couple of them and they have different values, so not sure which is correct.
Elevation / declination chart
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A simpleton's definition of Modified Latitude: A small amount added to your ACTUAL latitude/elevation which allows your dish to track the arc more precisely.
Now if you want to try and understand the technical explanation...go right ahead. I get lost when they start mentioning angles. lol.
From my experience your going to wind up pretty close to the modified declination settings anyway once you finish tuning your dish. How do I know this? Well first time i set up my dish i used the table in the instructions for the dish (non modified declination). Had an issue that i worked with titanium and KE4EST and wound up starting from scratch after taking measurements of where the dish was at the time. I then used the modified declination chart. What did I find? Well I still had to fine tune after Initial settings but it was way less then the first time because i was much closer to start with. Instead of goofing around for a couple of days I managed to get it pretty darn close in an afternoon. Then to get the most i could out of KU I spent about an hour the next day 1/8 and 1/4 turning this way and that to hone in my ku signals. Do I get all the Ku signals? No, but i get MOST of them and have since written this off as an issue with this particular dish as well as a couple of other oddities that i have experienced with this dish. I have another dish I want to swap to this spring and try over with, but overall for my first c-band dish im pretty happy with my results. So would I reccomend using the modified declination numbers? A resounding yes. Next time Im going to try to account for my actual latitude instead of my closest match on the chart. If all else fails i can always go back to the values listed on the chart.
And by the way, when using the chart linked above by KE4EST :
If you live near latitude 65, don't trust the chart blindly!
Declination offset angle is 1 degree off, there.
Otherwise it is a very fine chart, up to latitude 80 (and it is using earth radius 6378 instead of (mean) 6371, it seems, but that is peanuts...).
greetz,
A33
If you live near latitude 65, don't trust the chart blindly!
Declination offset angle is 1 degree off, there.
Otherwise it is a very fine chart, up to latitude 80 (and it is using earth radius 6378 instead of (mean) 6371, it seems, but that is peanuts...).
greetz,
A33
To make it even simpler set the declination as per the chart and adjust elevation for maximum signal on your due south satellite and everything else should fall right into place assuming the pole is perfectly level all the way around. Of course for fine fine tuning some small adjustments to that for declination on the end satellites and elevation towards the center satellites will probably be necessary. I just wouldn't pull my hair out to get that precise on initial measurements. Those angles will get you in the neighborhood but they'll have to be tweaked anyway.
Well, the whole point of these modified elevation and declination angles is that they follow the arc (almost) perfectly, so that tweaking shouldn't be necessary.
So to prevent time-consuming tweaking, I would invest in these initial measurements.
But of course, I'm not opposed to some tweaking, if you like.
greetz,
A33
I find that the numbers are good but sometimes accurately measuring a dish mount can be problematic. So we can use a meter and tweak the adjustments. The last dish I put up I took the effort to accurately measure the angles and was very pleased with the result. But I still want to put a meter on it and check the signal readings.
Meaning that using the chart for my location on my due south satellite the signal levels were so low I could only get the strongest transponders. I had to add almost a degree and a half of elevation to peak the signal and had to use almost a degree and a half more declination to get the end sats. Using a digital inclinometer and the pole was plumb to a tenth of a degree all the way around. So for me it worked best to use recommended declination and then peak for signal strength on the due south satellite and then increase the declination angle towards the end.
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