Try This Mod For W2AU Baluns For Greater Reliability
Pictured at the right is a W2AU 1:1 balun that had been in service in a 75 meter dipole for the past four years. These are usually very reliable units so I was surprised when I had two of these baluns fail in service. I opened both units that failed, in an attempt to see why they failed. The one at the right failed for two reasons. The two eyebolts coming out of the sides of the black top, loosened probably due to the strong winds here in Utah, that whip the dipole halves wires and constantly tug on the eye bolts causing them to loosen. Our winds often exceed 50 mph here near the mountains. Both of my baluns that failed, had this same problem. When those eye bolts loosen, you get poor to no contact from the internal connections. This mod is intended to use the old internal parts to rebuild the balun into a unit that would not fail with our tough weather conditions.
In additon to the loose eyebolts, the pictured unit failed because one of the solder lugs connected to one eyebolt, was never soldered when it was built and it simply fell out when I disassembled the unit. Many times over the years that this unit operated, I was plagued by an intermittant problem that I could never pinpoint. In the middle of a contact, my SWR would jump to about 1.4 to 1 from its usual near unity reading. Now I know why. Lack of a bit of solder and maybe a quick oversight by the builders quality control people. Don't get me wrong, I love the W2AU baluns. This is a fine product that I strongly recommend.
This mod involves removing the internal parts of your W2AU balun and installing those parts in a new housing with a couple of new bolts added. Pictured at the right are a brand new W2AU balun on the left and on the right, all black, is the modified unit as I rebuilt it. Notice that I used a slightly larger diameter PVC pipe (1 1/2 inch) because it is commonly available at most building supply centers. Also the end caps are flat ended as oppposed to the slightly rounded end caps commonly used on standard PVC. The top hanger eyebolt on the original balun was replaced with a eyebolt that has a 3/8 inch opening. Try feeding a rope through that smaller eyebolt when the rope is slightly frayed or its below freezing outside. The larger eyebolt also allows two passes of the rope through the hanger eyebolt.