Re: [TowerTalk] Yagi statcking order?

[Don <w7wll@arrl.net>]

I have a WT-51 I brought down from my last home sitting on some saw 
horses that has not yet gone up yet (currently just using my HG-70HD). I 
had a plate made back when with heavy OD rod having hooks welded to the 
outer plate rims that allows mounting the plate anyplace within the 
tower below the existing factory plate mount tabs.I can't find the 
drawing but can take a picture of it so you can see it. Bit rusty from 
the salt air here but easy to make. I dropped the rotator down from the 
top and then inserted a long aluminum mast I had. I Even left the old 
rotator plate in place, slid the mast through it. Thought about mounting 
another bearing there. New plates slided in easily from the tower bottom.
Don W7WLL

Don T W7WLL

On 3/17/2020 10:04 AM, Art Greenberg wrote:
> On Tue, Mar 17, 2020, at 12:53, sawyered@earthlink.net wrote:
> > With 17ft of mast exposed, how much is in the tower?
> Tower is a WT51. There is only one place to put the rotator where the 
> manufacturer
> placed welded rests for the plate, about 3 feet down from the top. Big, burly 
> bearing
> at the top plate.
>   
> > I have a Thrust bearing at the top of the tower and the rotor (Yaesu 2800)
> > at the bottom of the mast.  I have a second thrust bearing mid section but I
> > let it float unless I am doing maintenance requiring pulling the rotor.
> This would be my preferred arrangement, but its not an option the way this tower
> is made. If I had the expertise, I would consider adding rests for another plate
> farther down, but I do not. In that case I would definitely add 40/30 to the 
> SteppIR
> instead of stacking two large antennas.
>
> > I think the moment arm of the mast vs what's pushing against it in the tower
> > is a big part of the question.
> I understand that consideration. But as both the 3 element SteppIR and either 
> of the
> smaller 2-element 40m yagis are similar in weight and wind load, I'm not sure 
> it makes
> much difference what the stacking order is with respect to that issue. I think 
> height
> of the second antenna on the mast is more important. I don't think I can put 
> either
> antenna at the top of the mast (or anywhere near that high) for that reason.
>
> Art
> WA2LLN
> art@artg.tv
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