Another SG2100 Mounting Question

[PopcornNMore]

I am trying to create a mount for my 1.2m Channel Master antenna that is light in weight to be supported onto my SG2100 H-H Mount.

Looking at the manual, my dish bracket angle should be 25.5 (30 - 4.5 declination) for my area. My elevation angle should be 63.

I am thinking this is only because dishes come with mounts that have elevation settings. Why not apply a flat panel with brackets to the back of the dish and set the motor elevation to 88.5? Or am I thinking wrong?

On a BUD you only have one elevation setting when an actuator arm is attached. Why would this be different?

If an elevation is needed, I am thinking of creating a mount that is fixed at the 25.5 angle.

 

[PSB]

I guess you have seen this......

http://www.satelliteguys.us/showthread.php?t=42450&highlight=primestar+mount

The declination angle can be built right in.

 

[Shawn95GT]

I don't think that'll fly (just adding elevation at the motor). The elevation is fixed on the motor depending on your latitude. The dish elevation setting (declination) is the one you can monkey with.

If you change the motor's elevation setting it'll change how the dish tracks the arc.

 

[PopcornNMore]

I would have to disagree on that. I like thinking outside the box and I believe there is a better way. The only reason the SG2100 motor has you set your dish elevation to 30 minus the declination is to make it easier, because all dishes already have mounts.

What you are actually really doing is supporting TWO not ONE mount onto the pole. I also saw pictures where people installed their SG2100 pointing up just like a STAB. If you did this I believe West would become East and East become West on the SG2100.

 

[Shawn95GT]

I would agree if the motor had a straight pole and the dish moved on that axis - but it doesn't. That 30 - declination I think is from the the bend in the SG2100's motor's drive shaft.

You may be right - I'm going to try and model it and see if the motor elevation effects the shape of the 'arc' that the dish moves in. I think it does but at the same time I can't picture how.

I guess another test would be to break my working setup... add 5°-10° to the motor elevation, then re-peak the dish and see if it still tracks the arc. Maybe I'll get brave this weekend .

If I had another SG2100, I'd put the Voom dish on it and just track the e* sats for fun.

 

[PopcornNMore]

I would agree if the motor had a straight pole and the dish moved on that axis - but it doesn't. That 30 - declination I think is from the the bend in the SG2100's motor's drive shaft.

You are exactly right. This is my thought as well. It makes me wonder why the SG2100 motor's drive shaft bent 30 degrees and not straight. If it was straight you could possibly mount your dish flush with the SG2100 drive shaft.

Like I said previously, it is as if we are mounting a mount onto a mount. When you add an actuator arm to a BUD, it doesn't work this way.

I believe they designed the SG2100 with a 30 degree bend to compensate for the mount that is already on your dish to make it an easier installation. I am trying to eliminate the mount so that there will be less weight to support my 1.2M dish. I may just design one for use only in my area with a fixed 25 degree angle.

 

[Shawn95GT]

If the motor didn't have the bend it wouldn't skew the dish though...

 

[Shawn95GT]

I think that's the key. The declination (dish angle) setting affects how much the dish skews when the motor turns. If the motor is over elevated you'll have a lesser declination angle which will make the dish skew more for a given USALS command. I'm betting the effective Azmuth would get messed up as well.

 

[PopcornNMore]

I believe you are right Shawn. I am going to try a few experiments and post the results.

 

[Shawn95GT]

Cool. You'll laugh when you see my 'model':

 

[Stefan]

"When you add an actuator arm to a BUD, it doesn't work this way."

Of course it does. You either have a declination adjustment on a BUD or the BUD is prebuilt to a declination that will work in your area.

The bend in the arm in the motor combined with the elevation setting on the motor and also the declination setting on your dish work together to make the dish track the arc properly. Without all three set correctly it won't do it. The only exception to this would be if you lived directly on the equator or very very close to it. Then you could use a motor without a bend in the shaft and point the dish straight up because the clarke belt would pass directly overhead, but if you don't live on the equator you should follow the instructions. Otherwise your not going to get your dish to track the arc properly. It's not really that difficult.

 

[WRBreland]

Stefan is correct. On most BUDs there is declination adjustment if it is a polar type mount. The SKEW is done by rotating the pick-up device (Horn, LNB). This requires two (2) motor systems.

Most of the H-H motors have offset arms. This method takes care of dish rotation and skew.

 

[Stefan]

Here's a good link. If you go to page 3 it discusses elevation and declination and all those kinds of things. It's mostly about large prime focus dishes, but all the basic principles are the same for all dishes. Anyway, the bent arm on these type motors functions the same way a polar mount does on a big dish.

http://www.geo-orbit.org/sizepgs/tuningp2.html#anchor469886

 

[PopcornNMore]

Yes I agree, a BUD dish as an elevation and declination adjustment just like with an FTA setup. The shaft on the SG2100 is bent, so that it can properly scan the entire arc.

What I meant by being different is that when you add an actuator arm onto a BUD it does not change the mount. By using a SG2100 H-H mount, you are adding your existing mount onto it. It then is almost like adding a mount onto a mount.

I am going to design the mount for my 1.2m Channel Master dish to be almost like the following picture. This will be a lot less weight attached to my SG2100 H-H motor and will increase its life span.

 

[Shawn95GT]

Yes I agree, a BUD dish as an elevation and declination adjustment just like with an FTA setup. The shaft on the SG2100 is bent, so that it can properly scan the entire arc.

What I meant by being different is that when you add an actuator arm onto a BUD it does not change the mount. By using a SG2100 H-H mount, you are adding your existing mount onto it. It then is almost like adding a mount onto a mount.

I am going to design the mount for my 1.2m Channel Master dish to be almost like the following picture. This will be a lot less weight attached to my SG2100 H-H motor and will increase its life span.

That's looks pretty cool. If I had a 1.2M dish I'd try any which way to make it work too!

I was calling around today looking for a 1M+ dish locally and I think I'm talking myself into getting into a 4DTV setup - hehe.

 

[Stefan]

For some ideas on a mount that will be fairly light, you might want to look at the mount someone has constructed for their oval primestar dish. You can see it on this page.

http://www.dvbapps.com/hans/sg107_v-box.htm


You could probably do something similar for your 1.2m dish and it would probably be fairly lightweight.

 

[PopcornNMore]

Stefan, thank you for the link. Pete was able to find a similar link for me last month. I am currently working on a few ideas on how it could be improved.

Last night I hit gold! After several weeks of search after search, I found a fantastic site that is going to sell me the feed support arms and Channel Master feedhorn needed for my 1.2m dish. They are located in Naples Florida not too far from me. Their site is one of the best I have seen and their prices are fantastic. Here is their link:


http://www.futurevisionsat.com/index.html