Well, since things are slow around here… I’ll talk a bit about one of my ham radio projects.
I built a balun last week… For those of you who are ham operators you know what a balun is… for those who are not: a balun is a device used to match a balanced antenna to an unbalance antenna feed line. I use coaxial cable as a feed lint to my antenna. Coax cable is unbalanced and you get nasty radio interference on nearby devices if you don’t use a balun. My son used to complain when I talked on ANY HF band. Now he hears no interference any more.
I went to http://www.hamuniverse.com/balun.html and followed the directions fairly close to make a 1:1 balun. I had an old cable lying around, a couple of feet of PVC pipe and some zip ties so I was ready to go. The main difference between my balun and the one on the referenced web page: Mine is on a 2 1/2 inch piece of PVC pipe about a foot long and I drilled holes and mounted screws to the PVC. The added hardware makes it easy to change out wire elements for various radio bands. So far I’ve used it around 7.2 MHz (way down the left side of the FM Band which starts at 88.1 MHz). The folks I’ve talked to on so far it say I have a good signal so I’m fairly sure I did a good job, because as most of these guys have been doing this for years and can differentiate a good signal from a bad one.
The screws I mounted in the PVC are stainless steel, so barring any issues, the balun should last a long time. For now it’s mounted at the top of the pole I’m using as an antenna support, a 12 ft (3 four ft sections) inverted military camouflague pole inserted into the top of one of the vent pipes on my house.