My good friend Gene in the mountains of Wyoming gave me these plans for a great 20M Ham antenna.
He writes:
Just for grins, let me tell about my own homebrew design, intended for simple field use. I put together a cheapie portable 20-meter vertical antenna a couple of years ago, that must have set me back all of $10 to $20 or so, and it was pretty effective. First time I set it up was on a camping trip up in the Uintas, and as soon as connected, I raised Italy! It is basically a quarter-wave vertical with 1/8 wave radials angling down from a feedpoint up 4' or more off the ground. The whole thing is around 22' high or so. The quarter-wave radiating section can be metal tubing or copper wire, either is effective for low-wattage (100 watts or less) usage. Materials can be gleaned from what is available, or inexpensively bought from Home Depot or Lowes or the like.
I'll describe the construction, so it could readily be duplicated by a reasonably handy person:
Cut two 12' lengths of PVC pipe, one of 2" and the other of 1 1/2", so they could slide together. Get four 4" long 1/4" brass screws/washers/nuts, and a little more than 80' of ordinary single conductor stranded/insulated 14ga housewire. (I had bought a 500' roll of it from HomeDepot and it's lasted me a while!) A 5' steel pipe I had lying around and a few screws and automotive wire connectors, 11 plastic or wooden tent stakes, plus a few feet of RG-8X coax with a PL-259 connector on one end, essentially filled out the bill of materials. Tools were the usual, a drill, screwdriver, etc.
I slid the two PVC pipes together so they overlapped about 1 1/2' in the middle - they needed to be at least 21' long after overlap. Drilled two 1/4" holes in the middle, through where they overlapped, so they could be fastened together, and another pair of holes 4" apart, the upper one 16 1/2' down from the top of the overlapped sections. Cut a piece of the housewire about 16 1/2' long, crimp/soldered a smaller connector on that end and a larger one on the other end (to fit the 1/4" bolt). Then I cut 8 chunks of the 14ga wire about 8 1/2 ft long, stripped a couple of inches of insulation off one end of each, and connected and soldered all of them together on that end, with a few inches of one wire left long for a connection to the coax. Stripped the insulation off the end of the coax for 3" or so, and crimp/soldered 1/4" connectors on each of the two leads. That was the basic fabrication before setup.
In the field, I rapped the 5' steel pipe into the ground a foot or so. (Should have gone deeper with a longer pipe, but that was what I had, and I wanted at least 4' sticking out of the ground. That deep wasn't far enough to stabilize the vertical upright, so I did end up needing to use some 1/8" poly rope for 3 guys, with their tops secured to where the PVC sections came together - probably a good idea in any case! I screwed the two lengths of PVC together in the middle. The 1 1/2" PVC was the top section, so I secured one end of the 16 1/2' chunk of the housewire to the top of it with a self-threading screw, and ran it along the side of the pipe as far as it would go, down to the upper hole of the two I had drilled there.
Ran the screws and washers thru the coax leads. Then ran the screw with the center coax connector through the upper hole, and the one with the coax shield connector through the lower hole (that is critical). I tightened the nuts temporarily. Time to raise the vertical!
With some help, I held the PVC pipe up vertically, and slid it over the top of the steel pipe. I found I needed to run the three guy ropes out equidistant about 15' from the base and stake them down well. Time to emplace the 8 insulated radial wires. I secured the connection of where all 8 came together to the lower screw connected to the coax shield. Then I ran out the wires equidistant from each other around the base and wrapped the ends around the non-conductive stakes and taped over the copper sticking out of the wire. Note that there is high voltage on the ends of those wires, so bare wire is a no-no -- they need to be protected from human/animal contact! The simple taping job was likely not enough -- it would be best to put a 3" insulator on the end of each and tape the connection, before securing to the stakes, but this was a quick-and-dirty installation. And it worked like a champ!
I hope you can get a decent mental image of this antenna as erected. Perhaps when Springtime comes to the Rockies, and we can see the ground again, I will put it back up and take some pix for posting!
Notes --
- For the 20-meter vertical, we need an overall length of at least 21' of PVC. To make the antenna more portable, it would probably be better to use 3 sections of PVC, with the top section being 1" pipe. Then each section could be about 8' long, more manageable. I suppose one could even use 4 sections, so long as the pipes were of graded sizes to nest into each other.
- I got the idea for the 8 radial wires only 1/8 wavelength long, descending on an angle to near the physical ground, out of a QST Magazine article of a few years ago, which reported on tests done with different radial configurations. The eight 1/8 wavelength radials on about a 45 degree slope from the coax feedpoint connection seemed to give very good results, even better than longer radials.
He writes:
Just for grins, let me tell about my own homebrew design, intended for simple field use. I put together a cheapie portable 20-meter vertical antenna a couple of years ago, that must have set me back all of $10 to $20 or so, and it was pretty effective. First time I set it up was on a camping trip up in the Uintas, and as soon as connected, I raised Italy! It is basically a quarter-wave vertical with 1/8 wave radials angling down from a feedpoint up 4' or more off the ground. The whole thing is around 22' high or so. The quarter-wave radiating section can be metal tubing or copper wire, either is effective for low-wattage (100 watts or less) usage. Materials can be gleaned from what is available, or inexpensively bought from Home Depot or Lowes or the like.
I'll describe the construction, so it could readily be duplicated by a reasonably handy person:
Cut two 12' lengths of PVC pipe, one of 2" and the other of 1 1/2", so they could slide together. Get four 4" long 1/4" brass screws/washers/nuts, and a little more than 80' of ordinary single conductor stranded/insulated 14ga housewire. (I had bought a 500' roll of it from HomeDepot and it's lasted me a while!) A 5' steel pipe I had lying around and a few screws and automotive wire connectors, 11 plastic or wooden tent stakes, plus a few feet of RG-8X coax with a PL-259 connector on one end, essentially filled out the bill of materials. Tools were the usual, a drill, screwdriver, etc.
I slid the two PVC pipes together so they overlapped about 1 1/2' in the middle - they needed to be at least 21' long after overlap. Drilled two 1/4" holes in the middle, through where they overlapped, so they could be fastened together, and another pair of holes 4" apart, the upper one 16 1/2' down from the top of the overlapped sections. Cut a piece of the housewire about 16 1/2' long, crimp/soldered a smaller connector on that end and a larger one on the other end (to fit the 1/4" bolt). Then I cut 8 chunks of the 14ga wire about 8 1/2 ft long, stripped a couple of inches of insulation off one end of each, and connected and soldered all of them together on that end, with a few inches of one wire left long for a connection to the coax. Stripped the insulation off the end of the coax for 3" or so, and crimp/soldered 1/4" connectors on each of the two leads. That was the basic fabrication before setup.
In the field, I rapped the 5' steel pipe into the ground a foot or so. (Should have gone deeper with a longer pipe, but that was what I had, and I wanted at least 4' sticking out of the ground. That deep wasn't far enough to stabilize the vertical upright, so I did end up needing to use some 1/8" poly rope for 3 guys, with their tops secured to where the PVC sections came together - probably a good idea in any case! I screwed the two lengths of PVC together in the middle. The 1 1/2" PVC was the top section, so I secured one end of the 16 1/2' chunk of the housewire to the top of it with a self-threading screw, and ran it along the side of the pipe as far as it would go, down to the upper hole of the two I had drilled there.
Ran the screws and washers thru the coax leads. Then ran the screw with the center coax connector through the upper hole, and the one with the coax shield connector through the lower hole (that is critical). I tightened the nuts temporarily. Time to raise the vertical!
With some help, I held the PVC pipe up vertically, and slid it over the top of the steel pipe. I found I needed to run the three guy ropes out equidistant about 15' from the base and stake them down well. Time to emplace the 8 insulated radial wires. I secured the connection of where all 8 came together to the lower screw connected to the coax shield. Then I ran out the wires equidistant from each other around the base and wrapped the ends around the non-conductive stakes and taped over the copper sticking out of the wire. Note that there is high voltage on the ends of those wires, so bare wire is a no-no -- they need to be protected from human/animal contact! The simple taping job was likely not enough -- it would be best to put a 3" insulator on the end of each and tape the connection, before securing to the stakes, but this was a quick-and-dirty installation. And it worked like a champ!
I hope you can get a decent mental image of this antenna as erected. Perhaps when Springtime comes to the Rockies, and we can see the ground again, I will put it back up and take some pix for posting!
Notes --
- For the 20-meter vertical, we need an overall length of at least 21' of PVC. To make the antenna more portable, it would probably be better to use 3 sections of PVC, with the top section being 1" pipe. Then each section could be about 8' long, more manageable. I suppose one could even use 4 sections, so long as the pipes were of graded sizes to nest into each other.
- I got the idea for the 8 radial wires only 1/8 wavelength long, descending on an angle to near the physical ground, out of a QST Magazine article of a few years ago, which reported on tests done with different radial configurations. The eight 1/8 wavelength radials on about a 45 degree slope from the coax feedpoint connection seemed to give very good results, even better than longer radials.
No comments:
Post a Comment