SM3D12 Rotation Limits

[rckowal]

I've been running a SM3D12/dish installation through it's paces here using USALS positioning and discovered a disturbing hardware limitation it has.

My question; Is there some way to setup this motor so it can rotate (using USALS) through an arc from about 160 to 250 degrees? If not by USALS, how about DiSEqC 1.2?

For information, I used Pansat recommend 181 degrees (Detroit area south) as the setup reference azimuth. Receiver is Pansat 2300. So far, I've been able to receive 8 satellites that are between 174 to 214 degrees azimuth. I am able to position the system to my eastern most satellite at 150 degrees. However, when I try to go to the extreme westerly satellite at 252 degrees; the motor doesn't rotate to that position. It starts, then moves a few degrees and stops.

After reviewing the fine print in the manual, I find that this motor hardware is only capable of 95 degrees of rotation. I interpret that to mean that it's limited to rotating only 47.5 degrees to either side of the reference (south) setup position azimuth. So calculating what this means; 181 deg. reference position plus 47.5 deg. rotation limit equals 228 degrees azimuth. This limitation means that I can't drive the dish far enough to receive a number of satellites that are west of this limit.

Any & all help will be very much appreciated. Best, Dick

[gorgievs]

I tried the SM3D12 in Massachusetts and it couldn't move to Galaxy 10R. The rotation angle was too small. So, I understand what you're going through. I don't believe that there is anything that you can do because the SM3D12 has hardware limits at about +/- 47.5 degrees. My suggestion is to invest in a Stab HH90 motor. They are pole mount motors and have a rotation angle at about +/- 65 degrees.

[rckowal]

Thanks for the reply.

HH90 is probably too light duty for my 95cm dish. In fact, my dealer told me that none of the Stab HH series are recommended for this dish size. He also said that warranties are no longer being honored by Stab when this size dish is used.

Seems to me there should be a way to "trick" the motor by setting the (south) azimuth reference to a more westerly position - like maybe 200 degrees. Then using Diseqc 1.2, re-program receiver to think that 200 is really 180 south. Granted, you would give something up on the easterly side of the range but that may be an acceptable compromise for some of us. Also, USALS wouldn't work using such a "trick"!

I was hoping that some of the motor experts here could tell me if such a scheme might be possible.

Best Dick

[vj9999]

I am a little (not too much) confused with values you are using. I usually refer to satellites according to my longitude. I am at 88.1W . Considering 6o degrees east/west, that means I could og to 28.1W to 148.1 west. This is plenty for me to pick up anything from Hispasat at 30W to G10R at 123W. It would be nice to try Telstar 12 maybe but it is too low on the horizon anyway. My sg2100 had a little stoppers on each side so you could adjust E/W limits. I took it out completely and was able to go as far east as possible using 1.2, but everything pass hispasat is too low for me to see.

[dtsexpert]

Your dealer is correct if he/she is talking about STab 90 mount. The Stab 100 is able to drive a dish up to 1m, 1.2m for Stab 120. In fact, Stab mounts are very well-built compare to other brands. I am using a Stab100 to drive a 1m dish for almost a year, no problem at all.
Yes, there is a trick to make it far East or West, in other words make it to tracks only half of the arc.
Example:
Let say your due south sat is SBS6 at 79W, due to the rotation limitation, h-h mount can't see G10R. So instead of using SBS6 as your true south sat, you can use G11 is your "highest sat" of the arc, the mount will be able to see G10R. No change for h-h mount elevation angle, which is the your lat deg. The 2 things should be change are:
1. Dish elevation.
2. lnbf skew.
Off course, by doing this, the mount only track half of the arc (starting from G11 toward the West for this example).
Michael

Originally Posted by rckowal

Thanks for the reply.

HH90 is probably too light duty for my 95cm dish. In fact, my dealer told me that none of the Stab HH series are recommended for this dish size. He also said that warranties are no longer being honored by Stab when this size dish is used.

Seems to me there should be a way to "trick" the motor by setting the (south) azimuth reference to a more westerly position - like maybe 200 degrees. Then using Diseqc 1.2, re-program receiver to think that 200 is really 180 south. Granted, you would give something up on the easterly side of the range but that may be an acceptable compromise for some of us. Also, USALS wouldn't work using such a "trick"!

I was hoping that some of the motor experts here could tell me if such a scheme might be possible.

Best Dick

[rckowal]

Dtsexpert;

Thanks for the reply.

I'm having trouble following why the "mount only tracks half of the arc"?
Please help me to understand.

Seems to me that if I use G11 as "highest sat" that the motor should still be able to turn 45 degrees either side of it, rather than half (45 degrees).

When I say "highest sat" I'm thinking that the motor (which is electrically set to 180 degrees, south reference) is installed so that its 180 south is actually pointed at G11.

[dtsexpert]

It's a bit complicate to explain, but I will try my best:
Visualize the satellite arc as a rainbow. Your truesouth sat is the one in the center of the arc, which is also the highest sat of the arc.
1. When you set up your h-h mount correctly, meaning truesouth sat at 0 rotation degree. When the motor turn left or right, the elevation of the dish start declining, making it hit all the sats of the arc.
2. In my example SBS6 as the truesouth sats but you pick G11 as your highest sat, the mount will track half of the arc correctly (from G11 towards WEST). But when it turns towards EAST, it will not hit the sat correctly. Why? because the dish elevation starts declining when dish moves towards EAST. BUT the sat between the truesouth sat (SBS6) and G11R have dish elevation even higher than G11R, therefore the dish will only tracks half of the arc as I have stated.
Hope this clear.
Michael

Originally Posted by rckowal

Dtsexpert;

Thanks for the reply.

I'm having trouble following why the "mount only tracks half of the arc"?
Please help me to understand.

Seems to me that if I use G11 as "highest sat" that the motor should still be able to turn 45 degrees either side of it, rather than half (45 degrees).

When I say "highest sat" I'm thinking that the motor (which is electrically set to 180 degrees, south reference) is installed so that its 180 south is actually pointed at G11.

[rckowal]

Thanks for the very clear & concise explanation Michael. I understand completely now.

In thinking about trying to "trick" true south & your comments in the earlier post, I overlooked the fact that the motor elevation decreases at the east/west extremes of the arc.

I wonder why the satellite rotor engineers don't try to design more range into their products? For instance, if Stab can deliver 60 degrees each side of true south, why doesn't SD3D12 (only 45) offer the same? Ham radio or even cheap tv antenna rotors rotate nearly 360 degrees - but of course they don't have to deal with the elevation change.

[vj9999]

I am still confused why would you want to do this. You are in Detroit area which is approx. 83W. +/- 45 degrees lets you see anything between 38 (maybe you could catch Telstar 11 at 37.5W) to 127W (galaxy13/horizons1). That is really all you can get from your area (maybe going as far east as 30W to catch Hispasat). If you try to go any further west you can only get IA7 at 129W (which doesn't have much) and any further west is all C-band and few Echostar birds which don't have any FTA programming any way.

I have both SG2100 and SM3D12 and i like SM3D12 a little better, but I have lost ability to go to Hispasat and T11 since I put it up (but no big deal since I didn't go there that much anyway before with sg2100). One nice thing with sg2100 was that it would do +/- 70 degrees out of box.

[rckowal]

Vj9999,

I'm coming to the same conclusion as I learn more about what I'm doing.

This is my first adventure into satellite tv land. In fact, this is the first time I've tried to setup a satellite motor. That's why I'm here at this forum - to learn from those of you who have already done it.

Although I've read a great deal, it takes some time to digest (understand) what I read into practical knowledge. Additionally, I find that there is a great deal that is never written (for newbies) which is best learned by asking.

[dtsexpert]

Here is the relation between the rotion angle marked on the mount and the real rotation degees the mount needs to turns to hit one particular sat.
(sat longtitude - your longtitude) x 1.15
In this case, his true south is 83W, G10R at 123W, plug these info in the formular (123-83) x 1.15 = 46 degees.
Since the mount roation angle is +/- 45, he will not hit G10R.
Hope this clear.
Michael

Originally Posted by vj9999

I am still confused why would you want to do this. You are in Detroit area which is approx. 83W. +/- 45 degrees lets you see anything between 38 (maybe you could catch Telstar 11 at 37.5W) to 127W (galaxy13/horizons1). That is really all you can get from your area (maybe going as far east as 30W to catch Hispasat). If you try to go any further west you can only get IA7 at 129W (which doesn't have much) and any further west is all C-band and few Echostar birds which don't have any FTA programming any way.

I have both SG2100 and SM3D12 and i like SM3D12 a little better, but I have lost ability to go to Hispasat and T11 since I put it up (but no big deal since I didn't go there that much anyway before with sg2100). One nice thing with sg2100 was that it would do +/- 70 degrees out of box.

[vj9999]

I was under impression that (and the scale on the motor itself is marked +/- 60) that it will allow you 90-99 degrees of horizontal rotation. That calculation is to relate marks on the motor itsel to the actual degree. I still think that you can go 45 degrees in each direction no matter what.

Just to check. I just went as far east and west on my motor ant the arrow on the mount gets close to 60 on each side. taking that calculation into the account 60/1.15=52.

This had me confused originally as well.

[dtsexpert]

you are right. I just do some calculation for my mount. My truesouth sat is G10Rat 123. Using this mount, the most EAST sat is AMC5 at 79W, at AMC5 position, the mount reaches its EAST limit, so we can make a save assumption that the "real" rotation angle of this mount is +/-45 degs (G10R at 123 - AMC5 at 79) = 45 degs.
If one needs wider rotation angle, SG2100 mount might be a good mount to consider,which default limit setting is +/- 72 degs as I remember. You can manually adjust the EAST/WEST bars inside of the mount to make it turn further than +/-72 degs. I still like the built quality of SM3D12, it drives my 1m dish without any problem. I wish it could turn EAST/WEST a bit further.
Michael

Originally Posted by vj9999

I was under impression that (and the scale on the motor itself is marked +/- 60) that it will allow you 90-99 degrees of horizontal rotation. That calculation is to relate marks on the motor itsel to the actual degree. I still think that you can go 45 degrees in each direction no matter what.

Just to check. I just went as far east and west on my motor ant the arrow on the mount gets close to 60 on each side. taking that calculation into the account 60/1.15=52.

This had me confused originally as well.