MY WA5VJB "Cheap Yagi" Construction Details
The following are construction details of the antennas I built using the WA5VJB design information posted on the web. The pictures are of the first 902 MHZ yagi I built. Note that the elements are steel not copper or brass. I replaced these elements with #10 solid copper wire when the antenna didn't perform properly.
Tip #1. READ ALL THE ARTICLES PROVIDED!
This article is the best to understand the over-all concept of the "cheap yagi's. The link shown here leads to the best information for 902 and 1296 antennas that I could find on the Web.
I pre-cut all of the elements to lengh using the template. I suggest you also use the template markings for the boom using a fine marker or dab if paint on the elements. This makes centering the elements so much easier than measuing!
I then drilled all of the holes after center-punching all the element locations using the template. I used a 3/16" drill bit and wiggled it around a bit. I put the boom into a wood vise and hammered the elements into the wood. This assured a tight connection that holds the elements firmly.
Finally I attached the coax as shown in the article. Note that I put a dab of glue from my glue gun where the elements meet the boom. This was for weatherproofing more than strength. I also sprayed my anetennas with two coats of Minwax "Helsman" indoor/outoor clear urethane.
One of the articles suggests clipping the loose end of the driven element to adjust the tuning. I found that it was not necessary to do so with both my 902 and 1296 antennas; minor teaking of the match is possible by just slightly bending of the element spacing of driven element relative to the reflector and first director.
If you are building a 902 or 1296 antenna, I strongly recommend you use the CAD templates with the associated free CAD program. It reduces this three hour construction project down to an hour.
The boom material I used came from Home Depot. They have 1/2" x 3/4" hemlock wood moldings, stock number H3428. This is a very good wood and easy to work with.
When I constructed my 1296 yagi, the piece of wood I had was too long. Rather than cut it, I added extra three elements. The size and spacing of the additional elements were based upon projecting the size and spacing differences of the 10 element antenna using a spreadsheet. I have been told that I would have been better off not adding the elements but that's part of what the hobby is all about, experiment! The few tests I have been able to make indicate a clean pattern with a gain of..... who knows!