MOBILE POLE FOR A HAM RADIO ANTENNA By Cordell Vail KE7ZBQ

Transcription

1 MOBILE POLE FOR A HAM RADIO ANTENNA By Cordell Vail KE7ZBQ I wanted to build a mobile pole for my 2 meter J-pole Ham Radio antenna so I could take it with me anywhere I needed to go in an emergency. Here are the steps I went through to build it. Here is what you need to buy (see pictures below to identify parts): Parts: 2-10 chain link fence top rails (3 if you are making the 30 pole) 1 chain link fence rail coupler (2 if you are making the 30 pole) 1 roll #36 nylon string 3 Large 12 nails 4 Climbers hooks 1 roll Electrical Tape 50 to 100 LMR 400 coaxial cable 2 3 hose clamps 1 Fence Connector clamp 2-2 bolts (3 if you make the 30 pole) with wing nuts 1 2 bolt (2 if you are making the 30 pole) with regular nut 1-2 foot long electrical conduit pipe 6 long wire hook to hold the weight of the cable Here are the tools you will need: Tools: Hammer Flat Screw Driver Knife J-Pole Antenna (or whatever antenna you want to use) Ham Radio 4 ½ long bag to keep it in (5 ½ foot long for 30 pole) 1 friend to help you stand the pole up and stake it down. 1

2 Here is how you would connect the pipes together: 2

3 Putting the pole together: I went to Home Depot and purchased 2 chain link fence top rails. They were about $12 each. Because they were 10 feet long they would not easily fit into my car trunk. So I cut them in half. That let two of the ends fit into each other taking up 3 of the lengths of pipe. Then I bought one coupler to connect the 4 th length. I bolted them together. Noticed the bolt on the left is permanent and would not be undone. The bolt on the right I remove when I take the pole apart and I used a wing nut so I do not need a wrench to do it up or undo it. At the top of the highest section of the 4 poles I attached one of the fence connector clamps they use to hook up the fence. With this climbers snap hook, it makes a perfect place to hook up the guy lines at the very top of the pole. 3

4 I also purchased a 5 food section of PCV pipe that goes around the outside of the top pole to actually hook the antenna on. I did not want my copper J-Pole antenna hooked directly to the metal chain link fence railing poles. I drilled a hole though both PCV and metal pipe and put a bolt through. Again notice I used a wing nut to bolt it together so it is easy to take apart without any tools. Now I have a pole that is about 25 feet tall. 4

5 I figured the easiest way to secure the base was to get a piece of electrical conduit pipe that I could drive in the ground and then just put the antenna base pole over the top of it so it would not move side to side. Next I attached my copper J-pole antenna to the PCV pipe that is on the top of the last section of chain link fence pole. I use water hose connectors so they are easy to assemble and disassemble with a screwdriver. 5

6 Now I attached my 100 foot LMR 400 coaxial cable to the antenna pig tail. Notice I wrapped several wraps of nylon string around the cable and made a loop in it to anchor it with a heavy metal hook to the guy wire buckle so all the weight of that heavy LMR 400 cable would not be pulling down on the antenna pig tail connector. Because that string loop will be permanently on the cable I taped it with black electrical tape to protect it from the weather. 6

7 Then in each of the 4 sections of pipe I tied the LMR 400 cable to the pole with a nylon string tied in a bow that will be easy to untie when I take it back apart. I also put black electrical tape on the connector between the Pig Tail and LMR 400 but because I will want to undo that when I take the antenna down, I left a flap of tape on the end of the wrapping and folded it over so it was not sticky. That makes a tab that is easy to find and pull to undo the taping later. 7

8 I attached three nylon string guy wires to the pole. I used the heavier #36 string so it would hold more weight in case the antenna was up in a wind storm. Notice I used big nails as the stakes. You could drive those into black top if you needed to. I left the kitchen peering knife in the picture so you could tell how big the nails are. Now for the hard part, standing the pole up. There are three ways you can do this. Normally this would be a two person job. Let one person hold the pole upright after you stand it up and the second person go around and pound in the stakes to pull the guy wire stings tight. That is the easy way. A second way if you are alone is to put in two of the stakes with strings attached. Then hold the third string in your hand. When you stand the pole up the two strings behind you will hold the pole from coming over any further and you can then put the pole on the center stand and then walk forward holding the 3 rd string in your hand pulling on it as you go. That will keep the pole from falling back away from you and your first two stakes put in will keep it from coming forward. Then just go put the 3 rd stake in the ground. You don t have to have the lengths exact. You can adjust them to perfectly tight after all 3 are in place. 8

9 You do not need to know the exact distance to the stakes but if you want to If you want to know the exact place to put the nail stakes you can use the Pythagoras' Theorem The third method you can use is to lean the pole against something. That way you can put it up alone without a helper. For example in this picture I leaned it up against a tree that was not as tall as the antenna on the top to balance it while I secured the guy lines. 9

10 Then I put the guy lines in three different directions to secure the pole. I secured the first nail into the ground then worked around to the other two then adjusted the strings to make the antenna straight up and down. 10

11 The 3 guy lines are a little hard to see in this picture because of the trees and the smallness of the nylon string. When I take the antenna pole down it is easy to store the guy lines by just wrapping the nylon string around the nail. With a climbers hook on each string they easily snap into the one on the fence connector clam at the top of the pole. 11

12 Once it is taken apart it is a very small package that will fit in the trunk of your car. I made a 5 ½ foot long canvas bag to keep it in. Now it fits easily into the back of my trunk (with the back seats down so it goes into the back seat area. If you wanted to put it in a trunk without putting the back seats down, you could buy 3 chain link poles and cut them down to six - four foot lengths so they would all fit into the trunk. Now I am ready to take my Ham Radio and 25 foot high mobile antenna anywhere any time there is an emergency. 12