In reading some of the recent threads involving people having alignment issues, I was trying to figure out possible things which could cause confusion, and in the process decided to start a collection of data about various hardware.
First, one thing which has been a source of confusion in the past, has to do with "elevation" markings on mounts, vs "latitude" markings on the mounts. Basically, you have to be careful that you are sure what you are dealing with. This is because latitude markings are approximatly 90-elevation. Ie if you are at 10 deg latitude, you'd need an elevation of something close to 80 deg to see a satellite. I have seen dishes and mounts that are labled for latitude and others that are labeled for elevation. Usually this becomes obvious that there is a problem, except when the setting you're looking for is close to 45. When I see someone say they set the elevation to anything in the 40s, and are having problems, I typically think that perhaps they should be looking for 90-that angle on their settings. This can get VERY confusing at times, so if you are having problems, double think the situation, and make sure you aren't using an elevation reading when you should be using a latitude setting, or visa-versa. Many mounts just have numbers that don't say whether it's an elevation or latitude, but in general, if the numbers increase as you raise the dish higher, it is an elevation. If the numbers decrease as you raise the dish, it is a latitude scale.
Secondly, there has been some discussion of the offset angles of dishes, and we've said here, that that offset angle is generally in the range of around 22 deg. However not all dishes are the same. I did a quick search through spec sheets that I could locate (please add any data I've left out), and made a list of the actual offset angles of various dishes. (Sorry.... the forum software strips out spaces and tabs, making this hard to read, so I had to insert " . . . . . . . . .".)
Fortec - 65 . . . . . . . . .24.62
Fortec-80 . . . . . . . . .22.75
Fortec - 90 . . . . . . . . .24.62
Fortec 100 . . . . . . . . .24.62
Winegard-DS-3100-100cm . . . . . . . . .24
Winegard-DS-2076-76cm . . . . . . . . .24
Patriot-PTX-76 . . . . . . . . .26
Patriot-90 . . . . . . . . . 21
Patriot-PTX-90 . . . . . . . . . 26
Patriot-100 . . . . . . . . . 22
Circular-DTV-18" . . . . . . . . . 22.5
Dishnet-circular-18" . . . . . . . . . 22.5
KTI-18" . . . . . . . . .24.62
Azure Shine 90cm . . . . . . . . . 24.62
SignalMax-65 ? . . . . . . . . .28
SignalMax-85 ? . . . . . . . . .26.6
Channel Master ????
PARACLIPSE Millennium 90 . . . . . . . . .22
GEOSATpro 90cm . . . . . . . . .24.62
GEOSATpro 1.2M . . . . . . . . .27.3
So you see, that there is quite a range of possible values here, and sometimes even the same manufacturer has different dishes with different offset angles. The reason that I think THIS might be an area for confusion is that I see different mounting brackets, like the pole and bolt bracket versions sold by
Sadoun, and these brackets "may" be generic in nature, rather than specific for a specific dish, I don't know. But if so, the latitude and/or elevation markings on that mounting bracket MAY be offset from the real settings for that particular dish.
Ie, I see people talking about these settings being off by 5 degrees, and I can only think of 2 reasons that this would be true, and one is the above possibility of confusing elevation and latitude, and the other reason is that perhaps that bracket wasn't designed for the dish it is being used on. This is particularly likely for these Fortec dishes, one of which you see has a different offset angle than the others, so if they use the same bracket on all dishes, at least one has to be wrong.
Another issue, is the bend in the motor shaft of the dish motors. This angle means that you need different dish elevation settings for different motors. The
Sadoun web page has often confused me, because they have simple calculations for some motors, and you have to go to another page for other motors. Basically, the elevation you want is (and I may well make a mistake here) the motor shaft bend angle minus the declination. For example, at the
Sadoun site, they list a few motors that give equations like 30-declination, 46.5-declination, etc. This is because the motor shaft angles in those two cases is 30 and 46.5 degrees. I "think" that the reason that the other motors have separate web pages is that the calculation for them is based on an unnecessarily complicated formula that can be found at the web pages of the motor manufacturer. I decided to try to back calculate what the ACTUAL motor shaft angles are for those other motors, and I came up with 30 deg for the
HH100 and
HH120, and for the
HH90 the angle seems to be 45 deg.
This is no big deal, since you can use the Sadoun calculator, HOWEVER, in my research of this topic, I ran into a couple web pages that dissagreed with respect to just what the motor shaft angle is on at least one of the motors, in particular, the
SG2100. I've seen 2 different values mentioned for this, plus I've seen two different descriptions mentioned relative to whether the markings on the mount for this motor are labeled in latitude or in elevation. So this seems to be another possible source of mixed up settings. I would really advise trying to measure your motor shaft angle with a protractor or inclinometer, to verify the settings.
Anyway, I may well have some errors here in either the data or calculations, but regardless, I think that these are areas that are prime sources of confusion, and these are things that people should be thinking about if having problems.
) is the same way. I also do not remember which side is marked which way but believe standing behind the motor the right side is latitude.
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