Dish clamp location on rotor shaft

[Cincy]

I have an SG2100. In the instruction booklet it shows a dish clamped about half way down on the shaft. I've seen some pictures of setups where the dish is clamped high up on the rotor shaft.

It seems to me it would make a difference. Does anyone know if it does?

[never enough]

i have sg2100 and dont know what your talking about.is it new item mine has no clamp

[Sadoun]

Some dishes have one clamp and some have two. Better to install it towards the middle or bottom of the shaft.

[wejones]

Originally Posted by Cincy

I have an SG2100. In the instruction booklet it shows a dish clamped about half way down on the shaft. I've seen some pictures of setups where the dish is clamped high up on the rotor shaft.

It seems to me it would make a difference. Does anyone know if it does?

Basically, it doesn't matter where, up/down on the shaft you put the dish, unless where you put it ends up having the dish bump into something. However on the version of SG2100 that I have, there are some holes on the shaft, and depending on what kind of dish mount you are using, sometimes these holes can keep your dish centered on the shaft. Ie for proper operation of the motor, the dish should be pointing away from the motor, and with some mounts, using those holes helps keep the dish oriented right. If you don't use the holes, you have to be sure the dish is tightly clamped onto the shaft so it doesn't slip, otherwise USALS won't work right (USALS sometimes doesn't work right anyway due to other factors).
Also, although it doesn't matter where on the shaft you put the dish, it is best to keep it on the straight part of the shaft, rather than up where it curves, since that will change the offset angle of the shaft, which in turn changes the angle you'll need for the dish elevation. (not sure that is clear)

[Cincy]

Originally Posted by wejones

Basically, it doesn't matter where, up/down on the shaft you put the dish, unless where you put it ends up having the dish bump into something. However on the version of SG2100 that I have, there are some holes on the shaft, and depending on what kind of dish mount you are using, sometimes these holes can keep your dish centered on the shaft. Ie for proper operation of the motor, the dish should be pointing away from the motor, and with some mounts, using those holes helps keep the dish oriented right. If you don't use the holes, you have to be sure the dish is tightly clamped onto the shaft so it doesn't slip, otherwise USALS won't work right (USALS sometimes doesn't work right anyway due to other factors).
Also, although it doesn't matter where on the shaft you put the dish, it is best to keep it on the straight part of the shaft, rather than up where it curves, since that will change the offset angle of the shaft, which in turn changes the angle you'll need for the dish elevation. (not sure that is clear)

Yeah - I know the basics of it having to be on the shaft and not touching the angle at the top, and the aspect of it being centered rotationally on the shaft. I think my Weingard 30" had a hole which aligned with the shaft but the Fortec 36" dish I replaced it with doesn't.

I remember that in one thread either here or in another forum someone pointed out it shouldn't matter but said that the closer to the end of the shaft (in this case the bottom) is better because it "...increases the sensitivity..." because it has more 'swing length' per degree of arc.

[wejones]

Originally Posted by Cincy

Yeah - I know the basics of it having to be on the shaft and not touching the angle at the top, and the aspect of it being centered rotationally on the shaft. I think my Weingard 30" had a hole which aligned with the shaft but the Fortec 36" dish I replaced it with doesn't.

I remember that in one thread either here or in another forum someone pointed out it shouldn't matter but said that the closer to the end of the shaft (in this case the bottom) is better because it "...increases the sensitivity..." because it has more 'swing length' per degree of arc.

Well I'm not sure what post you're referring to, but the position on the shaft has absolutely no affect with respect to increasing the sensitivity, nor is there any affect relative to swing length per degree of arc. I *THINK* I understand where this might be coming from, because different positioning of the dish CAN give more movement of the dish per degree, however for there to be an improvement in resolution (which I think is what is really being referred to here), you need there to be more motor clicks per degree of arc, and when you have a dish hard connected to the motor shaft, you still have exactly the same number of motor increments per degree, so even though some dish positions may appear to produce more motion, there is no difference when it comes to what you see on your receiver.

Now, back to the holes on the shaft and the 36" dish. It is not the DISH that has to align with the holes, it is the dish mount. I have the Fortec 36" dish, and the mount I'm using uses the upper hole on the SG2100 motor shaft, and it aligns perfectly. I think the key here is what mount have you chosen? I'm using the pole mount option, and other people have used the U-bolt option. I can guarantee that the pole mount matches perfectly with the SG2100 that Sadoun sells, but I can't say the same for the U-bolt version.

THe other variable is the fact that there are more than one version of the SG2100, ie the one sold by Sadoun, and at least one other version made by competitors. Both look identical, however they are different. Not only are the motors different, but the motor shafts can be different. I have seen motor shafts with no holes, just one set of holes, and I think holes that aren't even centered in the shaft, in pictures I've encountered on the web.