Installing my El-Cheapo MF /LF Antenna
April 6, 2002
After all the calculations and planning are done, the time finally comes when you have to start cutting wire and climbing towers to make the antenna come to life. So, on a clear and cool Louisiana morning, I climbed my tower and completed the installation of my LF/MF antenna. As you will see from this article, it was not difficult to install. This simple antenna is an example of what you can do within the confines of a small city lot. And, it didn't cost a lot of money. Of course, the fact that I happened to have a couple of handy antenna supports helped a bit, too!
If you recall from my previous article about my plans for this antenna, it is simply a single vertical wire supported 2 meters away from the side of the tower. The vertical wire has a single top loading wire stretched between the tower and my rooftop mast. With the proper antenna tuner, it will be able to tune from 150 to 500 KHz.
Let's start at the bottom of this project and work our way up!
This picture was taken before the LF loading coil was installed on top of the antenna tuning cabinet. The antenna tuner is bolted to the bottom section of the tower. The antenna lead in wire exits the tuner from the right side, near the top of the tuner. From there, it extends upwards about 2 meters where it takes a right angle turn and then loops about 135 degrees around the tower and then meets the bottom end of the vertical antenna wire. The lead in wire is supported away from the tower by two sections of PVC pipe.
Standing in front of the antenna tuner cabinet and looking upwards along the tower, you can see the PVC support pipes and the lead in wire. If you look carefully through the tower, you can see the vertical antenna wire itself.
A 10 foot section of thin wall EMT extends from the tower and holds the lower antenna wire insulator in place. You can see the lead in wire coming from the antenna wire to the PVC lead in wire support pipes and then continuing on down to the tuner.
A better view of the antenna insulator. It is a made from a 14 inch section of 1/2 diameter inch PVC pipe with through holes drilled into each end to allow a length of #14 THHN wire to pass through the holes. The insulator is fastened to the EMT by simply wrapping the #14 wire around the EMT tube and twisting it to tighten it up. A 1 inch length of 1 inch diameter PVC pipe is slit through on one side to form a springy plastic "C" which is then slipped onto the end of the EMT to prevent the insulator fastener wire from coming off. This is cheap antenna construction! No clamps, hardware or glue is needed; just some PVC pipe and a roll of electrical wire! Oh yes, notice the orange electrical wire nut. I use these on antenna projects because they allow quick disassembly for modifications and repairs. They are better than soldering. All you have to do is install then so that they point up - no water buildup that way - and coat the wires with anti-corrosion compound before you apply the wire nut.
Here I didn't even bother to drill a hole to pass the lead in wire through the PVC pipe. I just took another length of #14 wire and twisted it around the end of the pipe.
Talk about cheap!! I didn't even bother to us any clamps for the PVC, I just attached it to the tower with some more #14 wire. This sort of construction may look trashy (well, OK, it is!) but the copper wire never corrodes or jams, and the insulation never rots. You can take stuff apart after 20 years with nothing more than your fingers, yet if properly done, it handles storms just fine.
After dragging my aching back (and about 50 pounds of tools) up the tower, I paused to check out the view to the west of the QTH. That's my van parked in the street, and you can see the rooftop mast I gave on the house. It supports a short spaced 6-element 6 meter beam. The rotor is located at the bottom of the mast, and the 20 foot high mast rotates through a set of floating guy rings. The far end of my W9INN dipole system and the far end of the LF/MF antenna loading wire are attached to the mast. The dipole is fastened to the roof mast about 1/3 up from the bottom, and the LF/MF load wire attaches to the top of the mast.
Pointing the camera down a bit, you can see the near end of the W9INN dipole antenna. There's a G6-144 antenna sticking up from the roof of the house, right side. The roof top mast is in the center of the picture. Notice the 4 inch wide copper ground straps running from the roof top mast down the left and right sides of the house to a series of ground rods. There are another set of ground straps also faintly visible running down to the ground along the front left and right roof ridges as well. Nothing like good protection from lightning!
Swinging the camera up and towards the northwest we have a nice view of the upper LF/MF antenna wire support and insulator. The same type of EMT is used here as I used at the bottom. Notice the lead wire from the vertical portion of the antenna which is running over to the top load wire insulator (shown hanging down) in the right bottom of the picture. The wires are spliced with ordinary electrical wire splices after gooping the wires with anti-corrosion compound. This seems to work as well as soldering and may be readily disassembled later for repairs or modification. Then there's also the side benefit of not having to mess with a hot soldering iron while on the tower. I really, REALLY hate it when I drop hot solder down my sock!
Climbing down from the tower and climbing up on the roof, we see that the far end of the top load wire is connected to the top of the roof mast. Here you can see the end of the wire and the PVC pipe insulator stretching down and to the right at a 45 degree angle from the top of the mast.
Here's a view of the vertical section of the antenna. The lower insulator support is plainly visible. The vertical wire is faintly shown leading up to the top insulator support. It is just barely visible at the top of this picture.
From the garage roof, you can see the upper insulator support pipe and the vertical antenna wire. The top load wire is there, but it's hard to see. The top load wire starts from the tower, not from the top end of the vertical wire! Some of the tower guy lines are also visible, as is my W9INN dipole antenna. The TH-3jr beam is impossible to use, since the neighbors tree has actually grown all the way over to the tower and hits the bean elements. (Now where's my chain saw when I really need it??)
Another view of the tower and the beam-eating tree. This picture was taken from the 30 foot level just below the point where the far end of the W9INN antenna connects to the roof mast. The LF/MF antenna top load wire is easily visible in this picture. You can also see the upper insulator support pipe extending to the left of the tower.
And this, folks, is the finished product. Here, the vertical antenna wire is not readily visible, but you can see the top load wire stretched between the mast and the tower.
73, Ralph W5JGV
The entire contents of this web site are Copyright © 2002 by Ralph M. Hartwell II, all rights reserved.