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 Antenna / Rotator Mounting Advice 
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Post Antenna / Rotator Mounting Advice
Antenna Mounting advice required please.

2 element, 10 metre antenna on the side wall above garage, its basically 2/3rds of a 3 element sirio
Access to this can only be up the pitched garage roof on roof ladders.

Used to be mounted as per the front view, with 12 inch TK brackets that held the pole very close to the wall (actually touching the edge of the roof tiles at the top) This gave quite a bit of support against the wind, as the pole hardly moved.

However, since the rotator was one of those cheapy TV type (AR 303) I was always nervous about the rotator itself failing mechanically and the top/stub mast coming off. Also, since its quite top heavy it was a ball ache to get it up vertical , when stood on the garage roof.

A few weeks back I moved the rotator to the bottom, so it sits on the bottom TK bracket, - I made a mount with a pivot.
I have added a nylon collar held by a slightly bigger U bolt on the upper TK that fits smoothly over the pole, which is how the pole turns at the upper TK. This allows me to release the top U bolt on the TK, and swing the whole pole down so it sits across the garage roof, allowing me to access the antenna from the gap between the garage and next doors.

The issue I have now is I had to extend the TK's (to 18 inchers) to clear the roof tiles so now the pole is only supported by the TK's. Its an alloy pole and wobbles at the upper TK point when its windy. In addition, given the type of rotator, and that fact that pole is 2 inch, its is not perfectly central, and during a 360 turn is tighter in one particular place, and it struggles.

I now have new rotator - used Yaesu G- 650, but would like advice on the following.

1. If I replaced the alloy pole for steel, would this would reduce the wobble maybe slightly?
2. If I put the 650 at the bottom, and replaced the nylon collar with a thrust bearing mounted (somehow) to the upper TK to support some vertical load, would this suffice?. The 650 will allow the pole to be central and hopefully smooth within a 360 turn

Ideally I would like to keep the ability to pivot the whole thing down, as the G650 is even heavier and more top heavy if mauling it on top of the garage roof (normally solo). Also more top heavy, means more wobble. and I can't get the upper TK any higher

Thanks in advance for any suggestions & advise etc

Steve


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G1XRJ / Steve
Sun Dec 06, 2015 10:36 pm
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 Antenna / Rotator Mounting Advice 
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Post Re: Antenna / Rotator Mounting Advice
Bore a hole in the garage roof ridge tile and seal with a small flue tile seal. Then have as big a rotator as you want in the garage, on the floor. You can use the floor mounted rotator as one pick up point and have another one or two higher up the wall, or even use the garage roof timbers as a support. Keep mounts well away from the wall's apex where the brick courses become short with little brickwork above! You could sleeve and pin the top part of the mast to the lower and just lift the topmost section from the lower, or fabricate a sliding collar and a pivot affair to swing the topmost section leaving it pivoted on the lower. Anyway, that's what I would do :) Tube rigidity in bend and torsion is mainly governed by its OD, wall thickness has a surprisingly small influence. So a 3 inch OD tube of say 1/16 inch wall thickness will be one hell of a lot stiffer than a 1.5 inch one with over 1/8 inch wall thickness, or even 1.5 inch round solid bar. Steel has a higher rigidity than normal soft alloys, but is the extra weight manageable? Alternatively tie the mast into the apex of the main house roof and use the timber work and spreaders rather than the brickwork as a support. Be adventurous, that's what insurance is for ;)


Mon Dec 07, 2015 5:03 pm
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 Antenna / Rotator Mounting Advice 
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Thanks for the feedback.

The pole isn't inline with ridge of the garage, since the house apex and garage apex are not in line.
Therefore the hole would need to be through a sloping tile.,
Whilst I can imaging how you could seal say a flue, that's fixed, how would you seal a pole that rotates within the hole?

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Mon Dec 07, 2015 6:20 pm
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 Antenna / Rotator Mounting Advice 
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G1XRJ wrote:
Thanks for the feedback.

The pole isn't inline with ridge of the garage, since the house apex and garage apex are not in line.
Therefore the hole would need to be through a sloping tile.,
Whilst I can imaging how you could seal say a flue, that's fixed, how would you seal a pole that rotates within the hole?

Its possible, I know of someone who did it with a manualy turned beam from within a loft "shack", by utilising a through hole sealed angled tile, with added "drip" top hat cone around the protruding pole, but I personaly would not recommend it!
Too much potential strain on the tiles, and future drip, drip, drip, headache for it to be long term beneficial.
Stick to outside, easily maintainable brackets and and bearings, rather than introduce a "hole" in a perfectly sealed roof structure.

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Mon Dec 07, 2015 6:41 pm
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 Antenna / Rotator Mounting Advice 
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Post Re: Antenna / Rotator Mounting Advice
G1XRJ wrote:
2. If I put the 650 at the bottom, and replaced the nylon collar with a thrust bearing mounted (somehow) to the upper TK to support some vertical load, would this suffice?.


This is the correct solution. For ease I would find a rotator cage and bolt it to the TK brackets. You could use hinges on the base plate of the rotator cage and that would allow you to tilt it over.

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Tue Dec 08, 2015 2:25 am
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 Antenna / Rotator Mounting Advice 
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Post Re: Antenna / Rotator Mounting Advice
Thanks all

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G1XRJ / Steve


Tue Dec 08, 2015 8:30 am
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