[TowerTalk] Swing Gate Mounts

[Grant Saviers]

I'm not sure about the swing.  Best to draw it out on the exact tower 
dimensions.  Also how the elements clear.

Grant KZ1W

On 1/30/2023 15:23, Steve Maki wrote:
> Yes - the X configured bracing, which gets all three legs involved, is 
> how we made all our swing gate mounts and collars in the late 90's. That 
> puts the rotor straight off the leg, which automatically gets you 300° 
> rotation, right?
> 
> -Steve K8LX
> 
> 
> On 1/30/2023 6:08 PM, Grant Saviers wrote:
>> 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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