How many degrees on 24in actuator

[nycrich]

I need to setup a 24in actuator jack to a 6 ft polar mounted dish. How many degees on the satellite arc can it pick up? I recalled using an 18 in actuator that gave about 90 degrees coverage. I am hoping to cover 22W to 129W. Thanks.

 

[SatelliteAV]

The degrees of coverage for a given throw of a linear actuator is dependent on the dish design. The placement of the connecting point on the dish ribs or frame determines the amount of degrees the dish will travel as the arm extends or retracts. The closer the connectinng point is to the pivot point, the greater the degrees of travel as a ratio to the arm movement.

I used to modify dishes to place the connecting point further out on the dish and use a longer arm to provide additional accuracy for the incremental movements.

 

[whatchel1]

There is no way of telling you. I redesigned a polar mount from center pivot to side pivot and was able to move from 13 to 150 degrees on a 12 ft dish years ago. So I was able to go close to a 140 degrees. It is completely related to the design. The reason for the redesign was to eliminate the break over point so that it doesn't go from pushing to being pulled on. It always had weight on it.

 

[nycrich]

Thanks for the info. I was under the impression that different lenghts of actuator ( 18in, 24in, 36in) would correspond to a certain lenght of travel on the satellite arc, that corrsponded to certain amount of degrees. I had an 18 in actuator on a 5.3ft dish and I remembered it was able to travel from 22W to 135W.
I am setting up a 24in actuator on a 6 ft Fortec C/Ku polar mount and was curious.

 

[SatelliteAV]

The length of the actuator arm can be a limiting factor if it will not allow the dish to travel to the physical limit of the polar mount travel.

Maybe someone with a Fortec Star 6' polar mount design will be able to provide the measurement between the two mounting points when the dish is placed on the physical limits. To reach 22W and 129W from Longitude 80 degrees, you will need about the same amount of travel east and west from the centered position.

 

[B.J.]

I agree completely with the above comments that the range you can get with any actuator depends upon how and where the actuators connect to the dish. I've read several posts in several forums about modifying the mounting points to get more range.

One issue to consider, however, when trying to get more range, is that with some dishes, the connection points are in an area whereby if you go past a certain point, that the actuator actually jams up against the side of the dish, or up against the side of the mount.

I used to have a SAMI dish (I wish I still had that dish), and the actuator connected about half way out the side of the dish, and if you pushed the dish a bit past it's highest point, the actuator would actually hit the side of the dish, bending it, and it was nearly impossible to pull it back via the actuator. To get this to work, it was necessary to extend the connection point out away from the dish a bit to keep it from jamming.

As mentioned above, you get more range if the connection point is closer to the rotation axis, and I also have a smaller dish that had such mounting points, however with this particular dish mount, the actuator would jam against the mount itself if you tried going too far. Again, there were ways to alter the position of the connection points to avoid the jamming thing.

But the bottom line, before trying to see how far you can go, while inside at the receiver, I recommend first putting the actuator through it's process while out at the dish, making sure that you aren't causing some physical damage to the actuator, and hopefully set some limits to make sure that you don't go too far.

 

[nycrich]

I'll connect my actuator and check the range of travel as soon as I could locate some actuator wires. I'll post back the results with pics of the connecting points.