Mast coupler questions ?

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gmham
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Mast coupler questions ?

Post by gmham » 21 Apr 2018, 16:46

Guys parts off this summer ant project is to get another 10mtr vertical up, decided to mount a 9 foot 2" metal pole to the side off the shed all nice and secure and then use one off them mast coupler sections to mount a further 6 foot pole on top off this 9 foot pole . Not sure if to get a 2" to 1.5" mast coupler and use a smaller diameter 1.5" mast or get a 2" to 2" mast coupler ? So question is are two 2" metal poles joined with a mast coupler fairly rigid bearing in mind the 19 foot vertical antenna on the end off the second section or go for the smaller diameter 1.5" pole on top off the bottom 2" one ?

Cheers.
John
.... Icom IC7300 HF /6 mtr
Kenwood TR751e 2mtr ssb






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ch25
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Re: Mast coupler questions ?

Post by ch25 » 21 Apr 2018, 16:59

Bigger diameter bottom. I would use aluminium pipe. Bolt together and that's all.
Chris
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gmham
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Re: Mast coupler questions ?

Post by gmham » 21 Apr 2018, 17:05

Ok cheers.
.... Icom IC7300 HF /6 mtr
Kenwood TR751e 2mtr ssb






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Re: Mast coupler questions ?

Post by Tim » 21 Apr 2018, 18:53

The mast couplers I've seen don't look strong enough, they are fairly thin gage, you should look out for the same type of coupler that is meant for coupling scaffold poles, these are much stronger and heavier gage, alternatively find a foot length of steel tube of the same gage as your intended mast and the same gage that will fit inside and drill 2 holes 2inces apart right through the lot, both sections, and bolt them together.

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Re: Mast coupler questions ?

Post by gmham » 21 Apr 2018, 23:34

Thanks Tim good info.
.... Icom IC7300 HF /6 mtr
Kenwood TR751e 2mtr ssb






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paulears
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Re: Mast coupler questions ?

Post by paulears » 22 Apr 2018, 08:36

Mast couplers are not devices intended to function on their own. Fine with guy wires, but the turning moment from side force is huge - once you stick an antenna on top of the extension. The half couplers that bolt together, sandwiching the joint are usually pressed. Best case, they bend and the top gets loose, worst case, the metal around the bolts fractures and it all comes down. The only real solution if you cannot guy is the ungainly side strapping with wide spaced staff clamps, but that's also a lot of extra weight too! If you could source thick wall tube with an internal diameter to fit the tube snugly, this would work pretty well, but just difficult to get hold of, and not cheap.

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Re: Mast coupler questions ?

Post by grafter » 22 Apr 2018, 13:14

How will you get the top pole with antenna into the lower one when it's 9ft off the ground? IMO it would be easier to just use a single 15ft pole, lift it into position and fix to the brackets on the shed and not have the bother of extra weight and a potential weak point. Would potentially save you falling off the shed roof too LOL
my friend grafter, seems like you are using a very offensive tone in the reply.

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gmham
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Re: Mast coupler questions ?

Post by gmham » 22 Apr 2018, 15:04

Couple off good points raised guys may have to think further with this one. !! Thanks again.
.... Icom IC7300 HF /6 mtr
Kenwood TR751e 2mtr ssb






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Re: Mast coupler questions ?

Post by DX-Digger » 22 Apr 2018, 21:01

If you are talking a wooden shed, the wind leverage it would have to deal with would be high.
If its only planned for summer then may be ok but in strong winds you are asking wood to take the strain of a metal lever, I dont think the
metal joiner would be the weakest part.
I am not sure how you have mounted it. but might be worth re-enforcing the shed???
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