Tower Mast Recommendation

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W4ATX, Jun 11, 2021.

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  1. W4ATX

    W4ATX XML Subscriber QRZ Page

    Looking for an *affordable* mast to use on top of my 30' Rohn 25 tower. HyGain TH3-MK4 Triband and an MFJ-1526 Dual Band base station antenna sharing the common mast. Dual band about 3 feet above the tri-band. I'm thinking about 10 feet of mast with about 4 feet contained within the tower turned by a HAM IV rotor.

    Has anybody used or have first-hand knowledge of the Universal Towers MAST2X10 aluminum tubing? With only 0.125 wall thickness, is this strong enough? (Not much wind at my QTH...)

    https://www.dxengineering.com/parts/uvt-mast2x10
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Little bit cheaper if you go here (see below) and that's for the same tubing but 12' long instead of 10' long and it's stock instead of "delivery in August," in case you want it sooner...
    hollowbar.PNG

    Since either 10' or 12' has to ship truck freight and is too long for UPS or other inexpensive carriers, shipping cost can be expensive; however Onlinemetals has stock in Atlanta, so it may be cheaper to ship from there (maybe...you can find out), or that may even be close enough for you to drive there and pick it up, avoiding freight cost entirely.

    https://www.onlinemetals.com/en/location-and-hours
     
  3. WB5THT

    WB5THT Premium Subscriber QRZ Page

    Are you feeling lucky or not? I have zero luck so my mast is 0.25" wall.
     
  4. KL7SG

    KL7SG Platinum Subscriber Platinum Subscriber QRZ Page

    1/8" is pretty thin and 6063 T5 has pretty low yield strength ( about 21 ksi)
    6061 T6 has a yield strength of about 40 ksi.

    Also Tennesee is in EIA RS-222-C zone A. This zone has a mean velocity of 70.7 Mile/Hr with peak velocities of 92 Miles/Hr.
    My EIA data is old but it should be kind of close.

    I would see if Universal Tower can help you make the choice.
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The hollowbar DXE sells is the same thing I referenced.

    I just recommended a possible alternate source.

    Personally, I use 2" OD, 1.5" ID (.250" wall) aluminum hollowbar myself for three beams on a 12' mast and have had zero issues for 20+ years. But I chose that mostly for the clamping pressure, which on my HF LPDA is enormous and I didn't want to deform the mast.:p For smaller or lighter beams that won't deform masts, the .125" wall is likely enough.
     
  6. N7WR

    N7WR Premium Subscriber QRZ Page

    What you are considering will fail. I agree with KL7SG--talk to someone who is in the tower/mast business and see what they recommend. FWIW I had 1/4 inch wall moly steel which was not overloaded fail in a rogue wind. Cost me the antenna, rotator and top 2 tower sections.
     
  7. KL7SG

    KL7SG Platinum Subscriber Platinum Subscriber QRZ Page

    Hi,
    I was not trying to challenge what you have said.
    I guess it is the engineer in me providing some data and a recommendation.

    I use 2" 4130 tubing with a 1/4" wall like N7WR.
    It is just a pain to have to replace the mast if it bends.
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'm an engineer also, but go more by personal experience after installing probably >100 antennas and towers over the years (it was my "business" for a while in the late 1980s).

    As we all know, anything can fail. And Murphy's Law has always dictated that a dropped tool will always land where it can do the most damage.:p
     
  9. K1LKP

    K1LKP Platinum Subscriber Platinum Subscriber QRZ Page

  10. K9XR

    K9XR Ham Member QRZ Page

    I will probably get some flack, but here goes. Go to Home depot or Menards and get a 10' piece of 1 1/2" ID Schedule 40 water pipe. I have used them for years and standard fare for them here in Illinois was about 3 ft. in the tower, a TH-6 just above the top of the tower, and a pair of Cushcraft 11 element beams vertical for 2 meter fm. The last one I had a Wilson 204 at the top and a Heavy Mosley S-401 Rotary dipole for 40 meters above it. It was taken down 18 years later when I moved. I have Never seen one fail. It would easily handle what you are proposing. If you are sketchy about it go the the lumber and get 10 ft. of Oak Hand rail. Flat on the bottom is fine. It might have to be persuaded to go inside the mast but it isn't a big deal. It may help you sleep a little better. At any rate seal the top with a 2"boom cap and tape it to the mast. One more thing, make sure that the ID IS 2". Anyway, the 1 1/2" water pipe is about 1.15/16" OD. and will fit the tower with minimal mast shimming of the rotor. I assume you have the top section that has the 2 1/4" OD tube. Some Rohn top sections will not take 2" mast. Depending what you have you might have to punch out the Aluminum bushing that usually comes with them.
     

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