A couple of weeks ago, I started working on a version of the DL6WU Yagi that I might be able to get going for this weekend’s Moonbounce activities. I cut and mounted all the elements, but frankly, the feed system is a bit more complicated than I would like so I didn’t get it finished. On the other hand, I have constructed the so-called “Cheap Yagi” of WA5VJB before, and its feed is very, very simple: the driven element is a hairpin and the coax is soldered directly to it. Nice, neat and simple. So, I surfed on over to here:
WA5VJB Cheap Yagis — Wood Boom
And started cutting some copper-bronze welding rod to lengths. But something disturbed me: the length of the elements weren’t monotonically decreasing. In particular, director 4 was only 11 inches long, but it was surrounded by directors which were 12 inches long. That struck me as bad. Very bad. So, I tried to search for the original article that these antennas were based upon, and found a scan here:
Close comparison of the dimensions for the 11 element 70cm antenna reveal that director 4 should be 12″ long as well. So, that’s what I cut. Tomorrow, I’ll drill the holes, hot glue the elements in place, and then solder the feedline to it. And, maybe I’ll try to test record a pass of AO-51 or something to ascertain that it basically works.
Wow Mark, you and I are doing the same thing! I read your earlier post about World Moonbounce Day, was very intrigued, and happened to remember WA5VJB’s cheap yagi document. So I dug it out and gathered the materials for the 11-el yagi this weekend. I built up my version over the last two evenings, using steel rod for the directors/reflector and brass tubing for the driven element. I’m just waiting for the RTV to dry tonight so I can solder my BNC jack to the driven element and try to tune it up. I’ll post more about my experiences with the antenna and Moonbounce Day on my blog. I’m looking forward to seeing how your version turns out.
73,
Jason NT7S
Good deal Jason. My own is a simple wooden beam 3/4″ square, and uses 1/8″ copper-bronze welding rod for elements. I’ll probably just directly solder the coax to the driven element using my big Weller Soldering gun, and secure it in place with a bunch of twist-ties. I also want add a camera tripod screw somewhere so I can aim it at the moon easily, although it’s not that heavy, in a pinch you might be able to wave it around handheld, which I’ll probably do to test it on AO-51 or the like.
I made the short version of this antenna before, using some aluminum wire, and it worked pretty well, until I chucked it in the back of the SUV and forgot about it. Having stuff piled on top of it bent most of the elements. Since I only had about $3 invested in that one, it seemed to me just making a new, longer and better one would be a good idea.
Hopefully, I’ll get some good recordings this weekend.
Sounds like you got your element dimensions from the CLARC.ORG site.
They had many typo errors in their data and I tried to get it
corrected for years. Try the downloads at WA5VJB.COM
73 Kent WA5VJB