Monday, August 06, 2012

'Poor Hams' Wooden Antenna Mast

I was researching antenna mast ideas a 3-4 weeks ago because I want to put up an 80m Horizontal Loop antenna before the fall. I have a monstrous row of trees down one side of my property so that will supply two corners of this big square in the sky. I have the steel tower attached to the house and right next to my Ham Shack so that will provide the 3rd corner and a point for the feedline to connect. The 4th corner was a problem though...

No suitable trees, a power pole nearby that services my property and the neighbors. I needed to stay away from the power lines and yet get that fourth corner of the Horizontal Loop up in the air almost 40 feet.

Steel masts, steel towers? And then I stumbled on a couple websites talking about wooden masts.

They are cheap to build, are strong enough if supported by guy lines, and perfect for something like one corner of a wire antenna like the Horizontal Loop.

Panorama of the 42' total length wooden mast
For just under $200 I bought everything I needed from the local hardware store.
  • x1 - 16' 2x4
  • x2 - 16' 2x6
  • x2 - 20' 2x4
  • x1 - 20' 2x6
  • 5/16 ready rod with washers and bolts (these were cut to bolt boards together every 2-3' along the entire length. Six-inch bolts would also do the trick with no cutting.
  • 1 tube of PL-Premium glue.
  • 6 inch threaded steel pipe with threaded end caps (tilt over bolt). 
  • one hour rental of post hole digger. 4-foot auger (longest I could rent).
  • 5 bags of ready mix cement.
  • 5 eye bolts (4 for upper guy line connections, 1 for antenna wire connection).
  • 1 pulley for the line connected to the antenna.
  • 4 insulators for between the antenna wire and the support line.
  • 2 fifty-foot lengths of poly rope.
  • A 500-foot roll of 1/8 steel cable (lots of leftover).
  • 16 crimp sleeves for cable (1/8 size).
  • 8 saddle clamps for cable (1/8 size).
  • Best as I can remember that's the entire shopping list? I already had paint.
Weekend One
  • Assemble the mast on the ground or on saw horses
  • About 2 hours of work.
  • Paint the entire mast, at least two coats.
Weekend Two
  • Dig hole
  • Remove lower bolts and bend the tower over in the tilt-down position.
  • Lying on the ground it now looks like a large -- 7  --
  • Drop the lower section into the hole.
  • Level the lower section to perfectly vertical.
  • Mix and fill the hole with cement.
  • About 2-3 hours of work
  • Let the cement cure for 5-7 days.
Weekend Three
  • Attach eye bolt and pulley to the top of the mast, attach two lengths of rope connected with an insulator at the center through the pulley.
  • Attach 4 eye bolts about seven feet from the top (into the section of three 2x4's laminated together). One on each side.
  • Attach approx 75' of cable (or more) to each eye bolt, secure the loops from crimp sleeves. 
  • For the purpose of instruction, the tilt over portion of the antenna is pointed North. The tail of the tilt over portion is pointed South.
  • Have one person hold a guy line on the East and West side of the antenna. As it tilts up these people just keep the antenna from tipping to either side.
  • I was in the North position with the main part of the mast in the tilted over position. I used an aluminum extension ladder to support the weight of the antenna. I was able to extend the ladder one section at a time to slowly lift the weight of the tower in a safe and controlled manner.
  • A fourth person was on a step ladder in the south position at the tail of the tilt over section.
  • As my section went higher, his section came lower. 
  • Eventually, my ladder was fully extended up, and the tail had lowered so the person at the back could pull down and the transfer of weight shifted. He could lower the tail completely and the tower was now vertical.
  • Quickly reinsert the bolts below the tilt over point to secure the lower section of three 2x6's back into a solid block. Tighten the bolts so friction between the 2x6's is your friend.
  • Secure the East and West guy lines first, these are the weakest directions the mast has.
  • Next secure the North and South four guy lines. 
  • Adjust each line until taut while making sure to keep the mast as vertical as possible (use a level). 
  • Approx time 1-2 hours with the help of 3 other people. The two people on the guy lines do not have to be strong, the two on the north and south positions do all the lifting.
I made a PDF of a diagram to share.

And finally, I took all my photos from the last few weeks and put them into a video slideshow with some video at the end showing off the completed work.

Readers, search the blog for multiple update articles on the history of this mast.
Use the article name as the search term 'Wooden Antenna Mast'


AarenJensen said...

UPDATE #1 to the Wooden Antenna Mast blog post

AarenJensen said...

UPDATE #2 to the Wooden Antenna Mast article