I ran across this via google.
Make sure that this metal antenna support cannot come in contact with overhead power lines during tilting or at full height. Consult your local zoning authority for any restrictions in your area. Call your local "Miss Utility" prior to digging if there is any doubt about the location of underground utilities. Neither the author, nor your editor, nor CADX make any representation regarding the structural soundness of this design nor have we tested the design to determine the ultimate load-bearing capability.
The mast is made out of 1Â¼ inch rigid steel electrical conduit, (one could use even heavier conduit if desired such as 1-1/2 inch or even 2 inch) . The conduit comes with threaded couplings that allow two or more pieces to be joined together. The mast itself is made from two ten-foot lengths and one five-foot length of the conduit screwed together end to end. Two more ten-foot lengths are partially buried in the ground and are used to serve as the mounting base for the mast.
To begin the installation I used a post-hole digger to dig a four-foot deep hole. Prior to setting the pipes in the ground, I drilled two holes in each of them at a point that would be about three inches above ground level once the pipes were set in the ground. These holes, as well as 2 holes in the bottom of the 25-foot mast would all line up and serve as the pivot point so the mast could be tilted over.
I then put two ten-foot lengths of the conduit in the hole with 6 feet of each pipe protruding above ground level. These two pipes were set in the ground side by side with about two inches of space between them to allow for the 25-foot mast. They serve as the base that holds up the 25 foot mast.
After carefully checking the pipes to make sure they were perfectly plumb (i.e. vertical), I filled up the hole with four sixty-pound bags of concrete mix. This gives the mast a very solid base. Once the concrete has set, the mast was ready to be erected.
I inserted an 8-inch long by Â½ inch diameter bolt through the holes for the pivot point. I also drilled two holes in each ground-mounted pipe at a point about three inches from the top of each pipe. I then drilled two holes in the 25-foot mast at a point which would line up with these holes at the top of each ground mounted pipe once the 25 foot mast was tilted up to it's fully erected position.
I inserted another 8 inch long by Â½ inch diameter bolt through these holes to hold the mast in the erect position.
I took advantage of the base mount pipes being threaded on the ends and screwed caps on them to keep the weather out. Even the very top of the mast where the 5 foot section of pipe is, I had that threaded at the hardware store so I could screw a cap on it to keep the weather out.
To mount the Alpha Delta Sloper antenna itself to the mast, I drilled two holes at a point about three inches from the top of the mast and inserted a stainless steel eye bolt so I would have something to hook the antenna to. All bolts, nuts, and washers are galvanized and/or stainless steel to ensure long life without rusting.
I also used clear silicone sealant at all points where holes were drilled to seal out the weather.
All that was needed to secure the coax cable as it traveled from the antenna down the mast was some plastic, UV resistant, cable ties that are available at Radio Shack. These cable ties made it a very neat looking installation. I wrapped a cable tie about every 12 inches around the mast to secure the coax cable to the mast. One could use electrical tape to wrap around the mast to secure the coax cable as it travels down the mast but the tape would eventually come loose and start flapping in the wind.
Now when I want to tilt the mast down to work on the antenna all I have to do is remove the top bolt that is at the approximate 6 foot level, and walk the mast down to the ground. Simple and safe!
I would recommend that you use only a lighter-weight wire type antenna on this mast because the antenna will exert a pulling force on the mast in only one direction since there are no guy wires pulling in the opposing direction. Too much of a pulling force (weight) could cause the couplings that connect the 10 foot pipes end to end to become weakened and possibly break. A home made end fed long wire antenna or dipole antenna should not be too heavy as long as the antenna is not extremely long and not made out of too heavy a gauge of wire. You could even erect 2 of these masts, one at each end of the antenna. The Alpha Delta Sloper is a somewhat heavier antenna than a plain long wire or dipole because it has large coils in it so I am a bit more concerned about the mast than I would be with a lighter weight plain end fed wire or dipole antenna mounted on it. So far my mast with the Alpha Delta Sloper on it has been subjected to 50+ MPH winds and held up fine. I suppose that since the Alpha Delta Sloper has held up fine that an Eavesdropper Sloper and other similar antennas would also work well.
I bought all the necessary parts for this project at the local Menards Home Center and Radio Shack. The total cost was just under $100. That might seem like a bit much for a 25-foot mast but it sure beats the danger of standing near the edge of the roof and struggling with the old set up, especially in winter. It looks so much neater too, especially since there are no guy wires. It is also much cheaper than a commercially available 25-foot free standing tower or crank up mast which would cost hundreds of dollars.
A sketch of the mast is available by sending me an e-mail message requesting it. I will send you a jpeg format file with the detailed sketch.
Here is the parts list:
5 - 10 foot x 1-1/4 inch diameter rigid steel electrical conduit pipes
4 - 1-1/4 inch caps to screw on the ends of the pipe
4 - 60 pound bags of concrete mix available at any home center or hardware store
2 - 8 inch x Â½ inch diameter galvanized bolts
4 - galvanized washers to fit the Â½ inch diameter bolts
2 - galvanized nuts to fit the Â½ inch diameter bolts
1 - stainless steel 4 inch x 3/8 inch diameter eye bolt with 2 nuts and 2 washers
1 - tube of clear silicone sealant/caulk
1 - package of cable ties from Radio Shack"
Getting it Done.