Upside Down or Inverted Dish Installation.

[Babadem]

I know this has been posted a few times here by PSB, gabshere, Iceberg and a few others, and I have read some of the posted comments. But, I do have a few questions that I would like to ask for an Inverted/Upside Down Dish Insatallation:

1) Is the Elevation on the Dish the same? For example if normal elevation is 12° upright what should it be inverted? If not how do you determine the right elevation?

2) I know Azimuth remains the same right?

3) LNB skew: Let's say normal setting is 43.°, what will it be inverted?

4) Will there be an increase in Quality if a Dish is installed upside down or inverted?

 

[meinename]

Shouldn't it all be the same except for what the dish elevation "bolts" say?
LNB should be reoriented, 180°

 

[Babadem]

Shouldn't it all be the same except for what the dish elevation "bolts" say?
LNB should be reoriented, 180°

I really don't know. That's what I would like to know.

 

[vc2]

If the dish has an offset feed, the dish elevation angle setting will increase by 2 x Offset angle. There may not be enough adjustment range to achieve this. There shouldn't be any performance issues.

 

[Babadem]

If the dish has an offset feed, the dish elevation angle setting will increase by 2 x Offset angle. There may not be enough adjustment range to achieve this. There shouldn't be any performance issues.

What you're saying is.........if the normal elevation is let's say 10°, the inverted elevation setting should be 20°?

 

[B.J.]

I'm not sure that I'd agree. Although first of all, there are a couple options for how you turn the dish upside down, ie turning the whole mount upside down or keeping the mount the same, but turning the dish upside down on the mount. {I'm assuming this is an offset dish, since with a prime focus dish, there isn't really any difference between right side up and upside down, unless you have a spinclination mount.)
Anyway, if you turn the whole mount upside down, usually the elevation setting is set to give you your proper declination, given the BIG declination introduced by the bend in those motor shafts. For example, if you have a motor shaft with a 30 deg bend, and need a 6 degree declination, you set your dish elevation to 24. Now, if you turn the whole mount upside down, the motor axis bend still points 30 deg down, but now your dish elevation is 24 deg negative, giving you a total declination of -54 deg. There is no way to recover from this.
If you just turn the dish itself upside down, you'd be hit by the fact that the dish elevation is calibrated to compensate for the above mentioned offset angle, in the ~22 deg range, normally up. Like the other responder said, if you turn the dish upside down, now you have the dish aiming 22 deg down instead of 22 deg up, ie 44 deg in the wrong direction. The elevation adjustment may or may not be able to handle this, however there is sometimes the problem that when upside down the dish may bump into the mount/pole when turning, particularly when you'd have to dial in such a big elevation angle. ( I seem to remember this being an issue with one person I was communicating with once, although that may have been on a mount that didn't have an axis bend.).
Yes it can be done, and done right, but it isn't just a situation of turning the dish upside down and keeping the same settings. At a minimum, you'd have to dial in a significant elevation to compensate for the combination of offset angle/axis bend, etc, and in some cases this can require some modification.

 

[Mr Tony]

when using an upside down dish azimuth & skew are the same

elevation you have to play with...I dont know of any "scientific" setup...its all trial and error for me

 

[Anole]

Folks who invert dishes do so to get a very low-to-the-horizon satellite.
They are not motorized, and I don't see any reason to combine a motor with an inverted dish, unless in very rare cases.

And I'm with Iceberg on figuring out the elevation.
Not something I'd sit down and worry about.
Put it in the field; you'll see what you need to do; then do it!

 

[gabshere]

If the dish has an offset feed, the dish elevation angle setting will increase by 2 x Offset angle. There may not be enough adjustment range to achieve this. There shouldn't be any performance issues.

this could be quite possible but the inverted dish was explained to me to work best in extream northern (Or southern areas) where elevation is real low.

Folks who invert dishes do so to get a very low-to-the-horizon satellite.
They are not motorized, and I don't see any reason to combine a motor with an inverted dish, unless in very rare cases.

thats my understanding also

I also figured that inverting the dish wouldn't help me any most of my sats are 40-50 degrees so inverting the dish would get me pointing close to zero on elevation if i thought everything through.....

now inverting the diesqc motor shaft never tried it. but would put he motor in something like the stab motor ...... now reversing a motor shaft . i have done this , don't know what difference it made i did it mainly to support my heavy dish weight with my homemade mount. the mount has been redone.

i don't mind setting up a test dish and taking pictures of it normal and inverted but each location will be different for each dish & satellite.

I don't see any reason to combine a motor with an inverted dish, unless in very rare cases.

unless you wanted to be unique or had a fence in your way something out of the ordinary... so i agree it should be rare

 

[Cadsulfide]

THe only downside I can see is that it may become a birdbath, and collect water.

 

[neljtorres]

I know this has been posted a few times here by PSB, gabshere, Iceberg and a few others, and I have read some of the posted comments. But, I do have a few questions that I would like to ask for an Inverted/Upside Down Dish Insatallation:

1) Is the Elevation on the Dish the same? For example if normal elevation is 12° upright what should it be inverted? If not how do you determine the right elevation?

2) I know Azimuth remains the same right?

3) LNB skew: Let's say normal setting is 43.°, what will it be inverted?

4) Will there be an increase in Quality if a Dish is installed upside down or inverted?

No it's not the same here in Puerto Rico they do that crap when they installed me the Dish Network system they put 110 sat upside down but I asked them to fix it I live in a clear area with no mountains surronding me I have had something blocking the area we then you could put it upside down.

 

[migold]

I have a GeosatPro 90cm dish looking at 123°W, which is low to the horizon from my location. Due to the dish configuration, I had to invert the MOUNT to get the low angle. See the review at DVBresource.com on this dish for illustrations. They have a good diagram showing offset angle and dish aiming on this particular model. The problem only occurs with a fixed mount looking at a low to the horizon bird.

 

[Babadem]

I'm not sure that I'd agree. Although first of all, there are a couple options for how you turn the dish upside down, ie turning the whole mount upside down or keeping the mount the same, but turning the dish upside down on the mount. {I'm assuming this is an offset dish, since with a prime focus dish, there isn't really any difference between right side up and upside down, unless you have a spinclination mount.)
Anyway, if you turn the whole mount upside down, usually the elevation setting is set to give you your proper declination, given the BIG declination introduced by the bend in those motor shafts. For example, if you have a motor shaft with a 30 deg bend, and need a 6 degree declination, you set your dish elevation to 24. Now, if you turn the whole mount upside down, the motor axis bend still points 30 deg down, but now your dish elevation is 24 deg negative, giving you a total declination of -54 deg. There is no way to recover from this.
If you just turn the dish itself upside down, you'd be hit by the fact that the dish elevation is calibrated to compensate for the above mentioned offset angle, in the ~22 deg range, normally up. Like the other responder said, if you turn the dish upside down, now you have the dish aiming 22 deg down instead of 22 deg up, ie 44 deg in the wrong direction. The elevation adjustment may or may not be able to handle this, however there is sometimes the problem that when upside down the dish may bump into the mount/pole when turning, particularly when you'd have to dial in such a big elevation angle. ( I seem to remember this being an issue with one person I was communicating with once, although that may have been on a mount that didn't have an axis bend.).
Yes it can be done, and done right, but it isn't just a situation of turning the dish upside down and keeping the same settings. At a minimum, you'd have to dial in a significant elevation to compensate for the combination of offset angle/axis bend, etc, and in some cases this can require some modification.

The setup is not motorized. It is an offset Dish, a Phase III dish from DTV. I want to use it to pick up WhiteSprings TV, Galaxy 27 at 129°W.

 

[Babadem]

I have a GeosatPro 90cm dish looking at 123°W, which is low to the horizon from my location. Due to the dish configuration, I had to invert the MOUNT to get the low angle. See the review at DVBresource.com on this dish for illustrations. They have a good diagram showing offset angle and dish aiming on this particular model. The problem only occurs with a fixed mount looking at a low to the horizon bird.

I am trying to get Galaxy 27 @ 129°W using a phase III DTV dish. 129 is about 14° elevation where I live, and I'm not sure the dish setting will go that far down.

 

[B.J.]

The setup is not motorized. It is an offset Dish, a Phase III dish from DTV. I want to use it to pick up WhiteSprings TV, Galaxy 27 at 129°W.

Oh... I guess I missed that sorry. So I guess that rules out turning the whole mount over, and you'd just be turning the dish itself over. OK... like Anole said above, I can see how that would help you get lower to the horizon, as you'd be aiming 40-50 deg lower.

OK, as the girl from SNL used to say re violins in the street..... never mind.... sorry.

 

[vc2]

What you're saying is.........if the normal elevation is let's say 10°, the inverted elevation setting should be 20°?

Not quite.

I'm assuming that you are using a fixed mount KU dish with an offset feed horn - something like a Primestar dish.

For example - say, the satellite elevation is 40°. The dish most likely has an elevation scale that you would set to 40°. The built-in scale calibration takes into account the dish's built-in feed horn offset. Note that offset feeds are usually have the feed horn located on the bottom side of the dish.

Now you want to mount this dish upside down.

Suppose the feed horn is offset 30° degrees from dead center, and you want to mount the dish upside down. Your new scale setting would be 40°(satellite elevation) + 2 x 30°(feed horn offset) = 100° All I'm saying is that your dish elevation adjustment would no longer be calibrated and you would have to increase the dial setting by 60° to 100°. The dish would have to point higher in the sky and you may not have sufficient adjustment range to reach this setting.

If you are using a motorized polar mount, it becomes more complicated, because declination angle has to be considered.

 

[mikekohl]

Most Primestar and other similar offset antennas have offset angles between 22 and 25 degrees. Tipping an antenna upside down means that you have to allow two times the offset angle (22 x 2 = 44) plus account for the actual elevation angle. As others have previously said, the mathematics gets complicated enough to confuse most people and it is much easier to guesstimate the approximate elevation setting while using an In-line satellite tuning meter in the circuit to detect the presence of ANY signal. Once you're on to something, do a blind scan to further identify channels and satellites.

The only real reason to invert a dish is to avoid mechanical problems caused by a normal antenna having a true reflector elevation angle of less than zero / straight up vertical when incoming elevation is less than 22 degrees. Inverting the dish will point the reflector physically somewhere between 25 and 50 degrees in most locations, reducing the amount of atmospheric ground noise received when pointing at or below the horizon. This is usually a minor issue that is often beat out by the increase of problems caused when the reflector is pitched above a 45 degree elevation...causing rain to pool on the dish during downpours and killing the signals immediately. I tried dealing with HISPASAT's 13 degree angle here on an elevated dish one winter, and inverted the dish on the mount. The result was that signal was little or no difference in quality, but when it snowed, reception vanished because it collected on the surface of the antenna. Use a vertical elevation and it seldom stays.

 

[Mr Tony]

Dang Mike....13 elevation in Wisconsin for 30W

Here just a 150 miles west or so and the elevation is 9

 

[sattec]

the lady wanted them as high to roof edge as we could get them....

 

[adrian]

I have a sat motor tracking the Clark belt with the Apex satellite being at 49 degrees at true north in Africa.To enable me to view a satellite which is low on the horizon i will have to turn the dish upside down.For the dish to move freely by way of elevation i had to turn the sat motor up side down as well and modify the elevation setting plates. The sat motor arm is now pointing upwards instead of down.I am lost on the mathematics of how to determine at what reading the Apex satellite will be.(my dish has a built in offset of 22 degrees)Can someone please help.