jimlux wrote:
> Roger (K8RI) wrote:
>
>> trappaport@austin.rr.com wrote:
>>
>>> Some tower comanies have recommended I get 5" OD steel mast pipes, which
>>> will not work for my rotors that take a maximum of 2.5" OD mast!
>>>
>>>
>> How about having an adapter machined to get from the 5" tube to the 2.5"
>> rotator mount? It might be kinda heavy but should meet the strength
>> requirements.
>>
>>
I should have added "if the rotator is capable"
>>
>
> how about a toothed belt drive between rotator and mast. I'm assuming
> that the 5" OD pipe is very thin wall (either that, it's literally going
> to weigh a ton). But this is getting pretty non-standard. Maybe taking
> a step back and saying: do I really want to use a ham rotator for a 5"
> diameter pipe, with all the improvising and cobbling I'm going to do?
> If you're going to cobble, getting some other sort of industrial motion
> control drive might be a better plan. Perhaps a worm and ring gear?
> Toothed belt to gear motor? There's an enormous number of ways to turn
> moderate speed motors into heavy duty vertical axis rotation. How about
> an inexpensive rotary table as used on a vertical mill? Or a modified
> auto rear end (as is popular for hot-walkers for horses)?
>
>
Friend of mine that used to live in Ithaca MI, John WD8RXP, had a self
supporting system that was IIRC 180 or 190'. The base was 100-120' with
the top rotatable section setting down inside on a turntable mounted at
80'. The top of the tower base had a thrust bearing that was a big ring
with rollers. The motor (3 or 5 HP) drove the turntable through a BIG
worm gear reduction unit. I think it made the cover on QST in Aug or
Sept of 83 with the title of the article being "The Mid-Michigan Sky
Hook" He had stacked pairs on 20, 15, and 10. The 50, 144, and 440
arrays were mounted on a large tube extending on above the rotating
section of tower and were to be separately rotatable. Unfortunately
John passed on at a relatively young age and never had the chance to
finish the system. He worked down in Lansing with the goal of using the
440 link to control the station so he could work DX on the way to and
from work.
I have photos of the tower construction that I should put on my
page...IF I can find them. That rotator was *huge*. the QST cover photo
gives an idea as to size and there is one photo in the article that
shows the antennas, but it's small and doesn't do them justice. There's
one photo of my HT siting next to the leveling bolts for one leg of the
tower to show scale.
For the cover shot I laid flat on my back under the center of the tower
base with Ken (WD8RZE) working at the top of the base about 100' over me.
73
Roger (K8RI)
> Or, some sort of spring loaded idler wheel friction drive between motor
> shaft and mast (like the old record players used to use). Has the
> advantage of a sort of "breakaway clutch" if something jams. Put the
> azimuth sensor on the mast, and use a programmmable controller like a
> green heron (or any of dozens of industrial motion control boxes).
> You're already talking thousands of dollars for the rest of the system,
> so saving a few hundred bucks on the rotator may be a unwise economy.
>
>
>
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