Rotator Cage
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WA0CBW
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Hmmmm............I've never seen one like that. Why not just mount the rotor to the pipe and the antenna to the rotor. I wouldn't want to mount this on top of a pipe. That single clamp at the bottom wouldn't be much angular support. Maybe there is another clamp under the rotor shelf. Still looks awkward to me. Anyone else understand how this works?
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I want to mount the rotor on the top of an antenna mast that's 2-1/2" diameter (no tower). I do not want the weight the beam and mast to be supported by the rotor by itself.
WA0CBW
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So how does this work? It looks like the bottom would fasten to the mast and the antenna on a mast would be mounted through the top into the rotor. How does that take the weight off the rotor? ..........Ok, I figured it out. You have a thrust bearing fastened to the top of the cage. Duh......
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n5ims
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I haven't seen ones like what you've pictured, but these (Texas Towers, Rotor Plates Page) should be pre-drilled for your rotor and mount inside the tower top section. Which one you need is more dependent on the type of tower you have. Instead of a specialized cage, the shelf secures the rotor while the top tower section itself acts as the cage.
The concept is rational and makes sense. There should be a thrust bearing at the top, and then whole assembly transfers the weight of the antenna and it's mast onto the main mast or tower, and off the rotator. The rotator then just turns the antenna, it doesn't have to carry it as well. Works good, lasts long time. If the mast is 2.5" chrome moly steel, the tower will break before the mast does.
To the OP, I've never seen anyone who manufacturers rotator cages, but I've seen plenty of projects on the internet. You might try calling some place like DX Engineering to see if they have any ideas. They sell thrust bearings, among other things, so someone there might have an idea where to steer you. I expect you'll have to build your own.
To the OP, I've never seen anyone who manufacturers rotator cages, but I've seen plenty of projects on the internet. You might try calling some place like DX Engineering to see if they have any ideas. They sell thrust bearings, among other things, so someone there might have an idea where to steer you. I expect you'll have to build your own.
The rotor cage will serve two uses I think. It looks as though it would be for someone that could not or didn't want to go to the expense of a tower and also help take the load off of the rotor. I suppose one could get by with a lighter duty rotor. It looks as though even the rotor cage would not take the load off of the rotor without a thrust bearing.
Or perhaps a tower doesn't make sense. In many communities, for example, a tower requires permits and planning meetings, while a telephone pole does not. A pipe mounted on a pole, with the rotator cage on top could allow for a large antenna, no permits, and a modest investment in a rotator.
The whole assembly is pointless without the thrust bearing. With the bearing, the rotator bears no loading other than the turning forces of the antenna. Without the bearing, the entire weight of the antenna is on the rotator bearings, and the mast has the additional weight of the cage, which isn't helping the rotator at all.
I would caution against that approach.
If the install is going to put so much weight on the rotor that it might cause it to fail, then I would re-think the project. There is probably a reason you cant find a commercially made "rotor cage".
Just squeezing that rounded flat strap around your primary mast is not going to hold things. Unless there is a cup or some other way of locating and centering the mast on the bottom of the rotor plate that isn't visible in the photo, the whole thing will eventually just flop to the side ( not good).
I would expect that again, because there is a large antenna on top of all this that the rotational torque is going to cause a lot of twisting. If the rotor cage is just held by the friction of the flat strap clamped to the primary mast I can see that slipping after a period and then you dont know where the antenna is really pointed. If the mast was pinned thru that same flat strap you may get by for sometime, but it will eventually wallow out the mast or flat strap and sheer the pin. If there is enough torque applied I can see the possibility of twisting the entire rotor cage just below the rotor plate as there are no diagonal braces on the one in the photo.
Depending on how long the primary mast is, when it twists under all that torque it is going to stress what ever it is attached to as well, such as a roof clamp, chimney straps or or base plate.
I'm not trying to be a weener, I just dont want to see any one get hurt or property damaged all in the name of playing radio.
If the install is going to put so much weight on the rotor that it might cause it to fail, then I would re-think the project. There is probably a reason you cant find a commercially made "rotor cage".
Just squeezing that rounded flat strap around your primary mast is not going to hold things. Unless there is a cup or some other way of locating and centering the mast on the bottom of the rotor plate that isn't visible in the photo, the whole thing will eventually just flop to the side ( not good).
I would expect that again, because there is a large antenna on top of all this that the rotational torque is going to cause a lot of twisting. If the rotor cage is just held by the friction of the flat strap clamped to the primary mast I can see that slipping after a period and then you dont know where the antenna is really pointed. If the mast was pinned thru that same flat strap you may get by for sometime, but it will eventually wallow out the mast or flat strap and sheer the pin. If there is enough torque applied I can see the possibility of twisting the entire rotor cage just below the rotor plate as there are no diagonal braces on the one in the photo.
Depending on how long the primary mast is, when it twists under all that torque it is going to stress what ever it is attached to as well, such as a roof clamp, chimney straps or or base plate.
I'm not trying to be a weener, I just dont want to see any one get hurt or property damaged all in the name of playing radio.
I think my Hy-Gain TX2 Tailtwister rotor will handle a fair size beam with or without a rotor cage and the thrust bearing but I would like to have one anyhow. Someone told me there is a flange that mounts on the end of the mast with the same bolt pattern as the four bolts that fastens the rotor to the mounting plate. That would make perfect sense to me.
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Hygain does make a lower mast support that bolts to the bottom of your TX2 and that in turn can be bolted directly to the primary mast. As long as you dont have more than a couple feet of mast coming out of the top of the rotor it should work well for you. You still have the twisting torque on the entire mast to deal with as well as the side load from wind.
Good luck with the project and let us know how it turns out.
Good luck with the project and let us know how it turns out.
That particular lower mast support doesn't do anything for taking the load off of the top of the rotor.
I'm having to mount the rotor on the top because my Hy-Gain T2X Tailtwister rotor will not fit inside of a Rohn 25G. I used to use a Yaesu rotor and wrongfully assumed the tailtwister would also fit inside of a Rohn 25G. WRONG!
I wanted to mount the rotor down lower to the ground so I wouldn't have to climb the tower to get to it. Had I started with a Rohn 45G it wouldn't have been a problem.
I wanted to mount the rotor down lower to the ground so I wouldn't have to climb the tower to get to it. Had I started with a Rohn 45G it wouldn't have been a problem.
WA0CBW
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I think you have to insert it into the tower before you assemble the sections. It won't slip between the legs but it will fit inside the legs. Its probably too late for that now!
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I haven't put the tower up yet. The rotor will not go into the tower from the end either.
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