W9RE has a very nice design for his rotating side mount in the Sept/Oct., 1987
issue of NCJ using structural aluminum plate & angle. I am in the middle of
building one for a small tribander.
KM5G
Get Outlook for iOS<https://aka.ms/o0ukef>
________________________________
From: TowerTalk <towertalk-bounces@contesting.com> on behalf of Grant Saviers
<grants2@pacbell.net>
Sent: Monday, January 30, 2023 5:08:15 PM
To: towertalk@contesting.com <towertalk@contesting.com>
Subject: Re: [TowerTalk] Ring Rotors
[External Email]
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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