So I'm reading the manual for the SG2100...

[Shawn95GT]

And the manual tells you to look up the elevation / declination settings depending on your latitude. No problem so far...

It then tells you to set the elevation angle of the motor - no doubt from that table you just looked at. - No problem...

It then tells you to find you declination angle on the table and it's a small number - like 8°. It then says "Set the declination angle by the scale on the antenna dish. The reading on the dish scale should be 40° declination angle".

Why did They have me look up the declination angle if I'm just going to set it to 40°?

Maybe this will make more sense when I have this stuff in hand - lol.

 

[PSB]

You are right you will not really need the declination angle, just use the motor and dish angles from the Angle Table. Set the motor elevation and never touch it again. Then set the dish elevation, but this angle can be changed slightly (up or down) to peak your signal quality when on a satellite.

 

[Dave C]

It then tells you to find you declination angle on the table and it's a small number - like 8°. It then says "Set the declination angle by the scale on the antenna dish. The reading on the dish scale should be 40° declination angle".

Why did They have me look up the declination angle if I'm just going to set it to 40°?

What my book says is "The reading on the dish scale should be 30° - (MINUS) declination angle" "Please refer to the drawing on Page 3"

30° minus 8° = 22° the approximate setting on the dish scale.

Hope that clarifies it for you.

 

[Stefan]

"The reading on the dish scale should be 40° declination angle."

Go back and reread it again. I believe it says "40 - declination angle". So, if your declination angle is 8, then you set the angle of the dish to about 32 or somewhere thereabout. Of course you may need to tweak this later.

EDit:
What DaveC says may be correct. I've seen conflicting information regarding the SG2100. I've seen some places that say "40 - declination" and others that say "30 - declination". I don't know whether this is an error or perhaps there were 2 different models of the same motor.

 

[Ziploc]

From what I've read there were maybe two different arms used on the sg2100, one arm used a 30 angle and one used a 40 angle. I have the book that came with my sg2100 and it shows a 30 degree angle to the motor arm, been several years since I set mine up now.

The pole is of course vertical, the motor mounts to that there is an angle adjustment to the motor at the bracket. Then there is an additional angle adjustment between the motor arm and the actual dish. my dish has no angle indicator I had to peak it manually and get it aligned correctly on the arc.

 

[Shawn95GT]

"The reading on the dish scale should be 40° declination angle."

Go back and reread it again. I believe it says "40 - declination angle". So, if your declination angle is 8, then you set the angle of the dish to about 32 or somewhere thereabout. Of course you may need to tweak this later.

Yup - you got it, it does have the "-" in there.

I think SG2100 quickly got adopted as a name for a motor by different brands. I think this is why the different 30° / 40° arms.

That P990 or whatever it is seems to be the same as a SG2100 with a smaller swing radius... like 90° vs 140°.

 

[Stefan]

How are you planning to attach your primestar dish to the SG2100? I used the original mount turned upside down. I used 2 pieces of PVC pipe to go between the motor shaft and the primestar mount and adapt it to fit. I used a piece of 1.5" schedule 40 PVC pipe and a piece of 2.0" schedule 40 PVC pipe. It is necessary to cut a slit down the length of both pieces of pipe. The slit in the 1.5" pipe allows it to expand to fit tightly to the SG2100 shaft as the inside of the 1.5" pipe is slightly too smal to fit over it without the slit cut into it. The slit in the 2.0" pipe allows it to compress enough to fit into the Primestar mount. When you cut the slit in the 2" pipe you must make it wide enough to allow for the pipe to compress enough to fit. If I recall correctly I cut mine about 3/8" to 1/2" wide.

One other thing I had to do was trim some material off the mount with a dremel. If you look at the primestar mount where bolts tighten up and clamp the mount to the pole, you'll notice there is kind of a ridge or lip on one side that will butt up against the other side when the bolts are tightened to a certain point. This was probably done to limit the amount the mount could clamp down on the pole such that overtightening the bolts wouldn't result in compressing in the sides of the pole and distorting it's cross section into an oval. In order to make it work in this configuration and be able to compress the PVC pipe around the SG2100 shaft this ridge must be removed or partially removed to allow the bolts to be tightened farther and generate more clamping force. So that's what I did. The result is a pretty nice mount that's not to difficult to construct and allows for easy adjustment of declination by simply turning the adjustment bolt on the bottom (which was on top in the original configuration). Anyway, if you have the original mount, a couple of pieces of PVC pipe and a dremel handy, this might be something you want to look at trying.

 

[Ziploc]

I built my own lighter mount, pics and drawings here: http://www.satelliteguys.us/showthread.php?t=42450

 

[Shawn95GT]

I might give either of those a shot.

I had originally saw your instructions Ziploc but then I thought it might be cool to have skew adjustment... so I pretty much bolted the P* dish to a Dish500. It is yet to be seen if this ghetto attachment will work out but if I cna make the original P* mount work it'd most definately be stronger.

I've got a good week before I even get my reciever so I'll take the P* mount apart and look it over. I thought the whole problem with the P* mount was the sheer weight of it. The original elevation adjustment is kind of cool and I wouldn't mind retaining it.

 

[Ziploc]

I have/can do elevation adjustment of the dish in relation to the arm by adjusting a couple of nuts on the lower threaded rods which were really way too long in that photo so I cut them way shorter. downside is that there is just no angle indicator, the lower mount is setup so I can adjust the dish. It actually worked very well to help me fine tune the declination angle as I could run out a few turns on the nuts check how it tracked the arc using a signal meter, and go back/forth until thee signal was strongest along all points of the arc. once I tuned it on a pole in my driveway it was simple to recreate the proper mounting on a short eve mounted pole at the roofline. after fine tuning it a couple more nuts keep it locked in place, once in a while a good wind messes me up by a degree or two but it's simple to get back on track, it's usually the whole pole that has turned in my eve mount.

The regular mount is 9lbs and the homebuilt is about 2lbs. The Dish's skew adjustment is handled by the arm of the motor itself. Once you have the motor mounted and have the dish attached and peak it on a few satellites so it tracks the arc properly the dish automatically skews what looks to be 75-80 degrees at either end of the arc it travels.

Originally I built a test rig(a length of the pole/pipe using a threaded floor mount to a simple wooden X) that I could level/set on my driveway and tweak adjustments until I understood how it all went/worked together. This was a very fun garage project for me.

 

[Stefan]

Ziplocs mount looks very nice. That might not be a bad mount to go with. As for skew adjustment, my understanding is it isn't necessary on a motorised dish as the motor itself tilts the dish as it tracks the arc automatically adjusting for skew. Generally you set the skew to 0 on a motorised dish and this automatic tilting of the dish takes care of at. After all the optimum skew changes as you move the dish east or west from your true south satellite. This is why the motor takes care of it automatically as it moves the dish. So, if your going to use a motor you shouldn't need skew adjustment and if really must have skew adjustment on a motorised dish, the only practical way to really achieve it would be to use a polar servo like most of your large prime focus dishes use. It may be hard to find a polar servo that attaches to a c120 flange (which is the way the Primestar feedhorns attach to the LNB). Anyway, I think if your going to motorise the dish it's best to forget about skew adjustment an set it to 0.

As for the weight of my mount, it's true it's fairly heavy. However, I have seen people using the same method to attach the round 1.0 meter and 1.2 meter primestar/channel master dishes to the SG2100 and those dishes are bigger and heavier and also the mount used with those dishes is larger and heavier. If they don't have problems then I wouldn't think I would. Of course I could be wrong. One thing that might could be done is perhaps drill or cut some holes in the mount in certain places to remove some material and perhaps some weight. Anyway, I'll attach a few pics of my mount so you can see it. One of them shows a close up of the lip or ridge I had to trim down with a dremel. Note I'm not a photographer and only own a cheap camera so you'll have to excuse the quality of the pics. Also despite the way it may look in some of them my pole isn't leaning. That was just the angle I took the pics at.