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Best Mast Pipe

Discussion in 'CB Antennas' started by Brain the Dog, Aug 1, 2017.

  1. bob85

    bob85 Supporting Member

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    Homer
    aluminium scaffold pole is probably less expensive than poles meant for supporting antennas because its made in massive quantity,
    6082-T6, 4.5mm wall x 48.42mm or 1-29/32" diameter,

    i just bought 20 x 10ft galvanised scaffold poles for fencing, suppliers specs are 48.5mm x 4mm wall.

    tube with a nice telescopic fit suitable for antennas is less expensive in the US than it is here,



    Vortex sell 6082-T6 & aa6082-T6 but it comes in less than ideal wall thickness for building antennas, too heavy & not enough sizes available,
     
    tecnicoloco and HomerBB like this.

  2. Brain the Dog

    Brain the Dog Active Member

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    I just got some Schedule 40 pipe from the local plumbing company. It's very heavy, but I'm concerned: Holding the 21' foot pipe, I can make it wobble when I shake it. Hmmm...
     
  3. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Any pipe that long that you cannot wobble when you shake it will be too heavy to even lift.
     
  4. Brain the Dog

    Brain the Dog Active Member

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    It is said that Aluminum Pipe even at Schedule 80 would be much lighter.
     
  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Correct aluminum pipe would be lighter. If fact it would be approximately one half the weight of schedule 40 steel pipe of the same diameter. 21 feet of schedule 40 steel 2 inch pipe weighs about 77 pounds while 21 feet of schedule 80 aluminum weighs about 37 pounds. Schedule 80 steel would weigh 105 pounds. grab a piece of schedule 80 of either steel or aluminum in the middle and shake it. It will still wobble. Now stand it on end and clamp one end solid and watch it sway. THAT is what I was talking about. Any mast will sway. If it didn't it would simply fatigue and break. My mast is 2 inch ID ( 2.375 OD) schedule 40 21 feet long. It is sleeved with an 8 foot piece of schedule 40 steel beginning about 4 feet up from the bottom which allows for a heavy duty mast where it needs the most strength......right where it comes out of the top of the tower and for another 7 feet above it. The rest is single walled schedule 40. Antennas to be placed on it are a Hygain Explorer 14 with 40m add on kit for 10/15/20/40, a Cushcraft A3WS for 12/17m, a home made six element 6m yagi, a stacked pair of 13B2 yagis for 2m SSB and a 2m/70cm five foot vertical at the top. MUCH MUCH more wind load than you are looking at. Several mast strength analysis programs list survivability of this installation in excess of 80 MPh. I'm not worried. If I were to use aluminum I would go with NOTHING less than aluminum hollow bar stock and not regular aluminum pipe.
     
    NF822WNY likes this.
  6. Brain the Dog

    Brain the Dog Active Member

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    So, do you think I'm OK with the Schedule 40 stuff? Attached is a picture of my plan.
     

    Attached Files:

  7. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Not sure exactly what you are using for a mast. Lots of people misquote sizes so I am not sure if your 1.5 inch pipe is inside diameter or outside. 1.5 inch steel schedule 40 pipe is actually 1.9 inches OUTSIDE diameter and is pretty much standard mast size. My Trylon tower came with an eight foot length of galvanized 1.5 inch schedule 40 pipe. It was 1.9 inches outside diameter and would be plenty heavy for what you want. I actually used it to sleeve the inside of my 2.375 inch OD mast. Many years ago I mounted a Wilson Shooting Star (similar to a Moonraker 4) on 15 feet of 1.5 inch 9inside diameter) schedule 40 pipe which was mounted to a piece of four inch well casing bolted to the house. It survived many nor'easters and a couple storms of hurricane strength. Note I used 15 feet of this mast and MUCH higher wind load than you. IF the mast you propose to use is indeed 1.5 inside diameter with a wall thickness of 0.145 inches (schedule 40) you will be FINE. If that 1.5 inches is OUTSIDE diameter I still think you will be OK as long as you do not go higher than 9 feet above the support point. One thing I do NOT recommend as a mast is the thin walled swaged tubing that Radio Shack etc used to sell. It is OK for a SHORT mast but not so great for long masts or high wind loads.
     
  8. Brain the Dog

    Brain the Dog Active Member

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    Yes.... it's actually the 1.9 inch stuff. And the top of the mast will be about 9-feet above the highest wall-bracket, with the A99 antenna attached to that.
     
  9. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Go for it. (y)
     
  10. Brain the Dog

    Brain the Dog Active Member

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    To be sure, I was fixin' to insert a smaller-diameter pipe into the top 10 feet, to give it more beef. What do you think of that?
     
  11. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Not at all necessary with what you are planning.
     
  12. lionfish

    lionfish New Member

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    I've just bought 8 6-foot swaged aluminium tubes to make a 'mast'. These are only 1.25 inches diameter - is that wide enough? I was planning on guying it at the top and in the middle. Importantly this is a very temporary mast (1-3 days tops).

    This isn't actually for a radio project - instead it's a project to track bumblebees using some equipment that needs to be in the air (previously I've experimented with a drone and a tethered balloon). But radio people are the only people I've found who need to build such structures.

    Thanks for any advice!
    (new to the forum! Always had a bit of an interest in radio electronics + built a few basic circuits - but at the moment focused on this bee-tracking project! Maybe I should start a new thread, but just thought I'd ask in here. Feel free to tell me to move it to a new thread!).
     
  13. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    With 48 feet of that aluminum tubing only 1.25 inches in diameter you will need at least THREE sets of guys. That aluminum is pretty flimsy. I put up 40 feet of 3 inch aluminum irrigation pipe as a mast and it only has two sets of guys and really should have three.
     
    BJ radionut likes this.
  14. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    I would suggest using EMT conduit it is more rigid than water pipe and weighs less.
     
    oldtymer likes this.
  15. Redbeard U812

    Redbeard U812 Sr. Member

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    Used 2" dia. drill pipe, actually 2-7/8 OD. They come with couplings. Cut one short for the length desired below ground level, drive in with post driver. Screw another section into coupling. Used what I had and created a break over @ 16'. Overall height is 36'-0". The top section (about 8 feet) is 1" pipe with 1-1/2" used for bushings and top ring of the 2". Sets down inside concentrically and held with 3/8" dia. studs. One set of guys.
     
    S&W357 likes this.

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