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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