High Gain Yagi for 432MHz
(DJ9BV design)
Rainer, DJ9BV, did a great job with this report. Everything is well explaned, so nothing can really go wrong if you try to build the antennas at home.
Due to the design you can choose the lenght (gain) to fit your own needs. The antenna can be cut at every length. All mechanical dimensions are gathered in a table.
I build the BV70-8.5L, boom-length is nearly 6m. This is a very "dificult to handle" lenght, so I cut it into two pieces. These two pieces are joined together with suitable "U"-shape piece of metal (like Tonna and Flexa do). To mount the antennas to the mast I take cheap "exhaust pipe" clamp from local car parts supplier.
In front you can see a special homemade tool to cut a big number of elements with the same length. I found this somewhere in the Internet (I do not remember where).
Everthing must be checked before we go upstairs and outside ......
Al least everthing is bigger than I thought. I built the antenna on top of the roof of my house. One problem is that the mounting point is too high above the bearing. This must be done if the antennas are elevated. The lower antennas should not touch the ridge of the roof. I planned to push up the antennas after mounting all. That is nearly impossible, due to the weigh and the friction at the mast, even a pulley is used. At least I am restricted in elevation. Additional to that I do not really trust the KR500 to keep everything in place while stormy weather.
©FDbt, Oct.2000
