[TowerTalk] Ring Rotors

[Grant Saviers]

Might be better as a new topic "swing arm mounts"

Some expert advice I got was to use crossed A36 angle steel (2x2x1/4 or 
1.5x1.5x3/16) U-bolted to all three legs and mount the rotator close to 
the tower on a 3/16 plate bolted in the V in the outside gap.

Repeat for the top bearing, xx feet above the rotator.  Could use a 
stock "thrust" bearing or a simple UHMW block with all the load on the 
rotator.

The swing arms were about 33" long mounted the the mast, which was going 
to be 1-7/8" x 0.188" 1026 DOM.  The mast was to be 13ft between mounts 
so able to mount 2 yagis.  A triangular brace mast to arm and a stub 
mast welded on the arm to mount the antenna with a stock mast-boom 
clamp.  Of course YMMV.

It's important to have all three legs capture the loading.

Ideally get it all hot dip galvanized or do a good pant job.

And find a PE to recommend a design for the planned yagis.

Grant KZ1W

On 1/30/2023 11:32, Steve Maki wrote:
> On 1/30/2023 2:23 PM, Lux, Jim wrote:
> 
>> On 1/30/23 11:10 AM, Steve Maki wrote:
>>> On 1/30/2023 1:48 PM, Lux, Jim wrote:
>>>
>>>> On 1/30/23 9:46 AM, Grant Saviers wrote:
>>>>> I agree side mount + swing arm is a good option.
>>>>>
>>>>> Although my 7 K0XG R65 rings have worked great minus one motor 
>>>>> failure, I would do side mounts for future (unlikely) towers.
>>>>>
>>>>> The advantages of side mounts are lower cost & weight, using 
>>>>> standard rotators, and if desired with multiple beams on a long 
>>>>> mast between rotator and top support.
>>>>>
>>>>> The side mount disadvantages are less rotation (but still can get 
>>>>> ~250*), some offset load on the tower (use 6 guys or star 
>>>>> brackets), and easily fabricated or purchased unique parts, 
>>>>> although you/PE need a design.
>>>>>
>>>>> I think the updated Orion 2800 is a better choice than the Yaesu 
>>>>> for very big beams. 
>>>
>>>> I've been thinking about this, and I wonder if there were some "not 
>>>> too complex" scheme with an extra hinge point on the arm that would 
>>>> get you 360 degrees.  Not that I would build such a thing (would 
>>>> that I had room for it) - but I was thinking if you had an arm that 
>>>> is the length of a "face" of the tower, and some sort of offset 
>>>> crank linkage, you could get 360 of rotation from 240 degrees (or 
>>>> less) of movement from the primary arm.   My mind's eye has this as 
>>>> like a "wrist" that reaches around the tower. Yeah, you'd have the 
>>>> mass of the antenna as a cantilever load, which would put a bending 
>>>> moment on the tower.
>>>
>>> A swing arm where the rotor is mounted straight off a tower leg is 
>>> good for 300° easy. That's plenty as long as you have another antenna 
>>> to cover the dead zone. 
>>
>> Oh yeah, I figured that.. I was just contemplating "clever mechanical 
>> solutions" - The swing arm is actually a nice solution in general - 
>> simple, uses off the shelf stuff, can be added after the tower is up, 
>> etc.
>>
>> It's like the hinge plates for mounting an antenna on a tower/mast 
>> that pivots from horizontal to vertical - a simple clever solution.
>>
>> Of course, the other solution is to mount two (or three) Yagis and a 
>> combining network to phase them (or just switch). <grin>
> 
> Yep, I was trying to picture your idea. Back when linear actuators were 
> cheap (used in the satellite dish industry) I put some time into 
> thinking about a way to use one or two to turn a large yagi on a swing 
> gate. It never got past day dreaming and a little pencil scratching.
> 
> -Steve K8LX
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