Spacer to mount yagi antenna on smaller mast?

Kaleier1

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Dec 27, 2019
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I bought a 800Mhz yagi antenna that I mounted to a PVC pipe with an outside diameter of 1 7/8 inches using the two supplied U-bolts as an indoor antenna and it fits perfectly. However, there are a few frequencies I can't receive well so I want to put this antenna on the roof of my house pointed at the system with the frequencies I want to receive.

I have a TV antenna on my roof mounted on a mast that has an outside diameter of 1 1/4 inches that I would like to mount the 800 Mhz yagi on but the U-blots for the 800 Mhz yagi are of course too big. Rather than replace the mast (not even sure if the TV antenna would fit a bigger mast) is there some sort of a spacer I could wrap around the 1 1/4 inch mast and then mount the yagi to that? Thinking something like a square piece of rubber that would grip the mast as I tighten the yagi mount. It would have to withstand the weather too.

I have searched the internet and it seems no one has this issue. Channel Master makes a U-bolt with a nest assembly that looks like it would work except for the fact the U-bolt is only 1/1/4 inches across (from one threaded end to the other) but the U-bolts on my yagi are 2 1/4 inches wide.

I have attached 3 pictures of the antenna and the Channel Master U-bolt with nest assembly.
 

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phask

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Get a smaller U-bolt, drill new holes in the antenna boom if needed.

Lowes/HD may have Mast U bolts in the TV wiring section or just try the hardware section.
 

Kaleier1

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Get a smaller U-bolt, drill new holes in the antenna boom if needed.

Lowes/HD may have Mast U bolts in the TV wiring section or just try the hardware section.
I wanted to avoid that as to keep from messing up the antenna mount.
 

jonwienke

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With a U-bolt, as long as the mount mast is >50% of the size of the u-bolt, it will still grip the mast OK. If you run out of threads, use some washers.
 

Ubbe

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If the threads run out on you before you can tighten them enough and don't have enough washers or spacers, then turn the antenna upside down and insert the u bolts from the other side.

/Ubbe
 

Kaleier1

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Beacues it shouldn't be an issue. You should be able to mount that small light weight antenna to any smaller size mast pole using those U bolts.

/Ubbe
You would be correct if the threads of the u-bolt extended down most of the length of the bolt but they don't. The u-bolt is is about 2 3/4 inches from the inside bottom of the u to the end of the studs. The threaded part is 3/4 of an inch. That means with the bolts tightened as far as they go you would have a space of about 1 3/4 inches yet my TV antenna mast is 1 1/4 inch, leaving a 1/2 inch gap.

I found some rubber and foam pipe insulation for a couple bucks online. Going to go to the hardware store and check it out to see if it would work.
 

Kaleier1

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With a U-bolt, as long as the mount mast is >50% of the size of the u-bolt, it will still grip the mast OK. If you run out of threads, use some washers.
THe washers are a good idea because that is the issue. The length of the threads is not enough to be able to close off the gap I was alos thinking about a thin block of wood to put on the blue piece.
 

Kaleier1

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If the threads run out on you before you can tighten them enough and don't have enough washers or spacers, then turn the antenna upside down and insert the u bolts from the other side.

/Ubbe
That's actually a real good idea. Thank you.
 

ka3aaa

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geta piece of all thread, heat it until its cherry red, bend your own, done. U bolts come in all sizes and lengths if you look around.

Anothe option is use UV resistant ty wraps or cable ties, just use more than one on each attachment point.
 
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