Build your own 10 meter YAGI!
This is the plans and instructions for a 10 meter, direct fed beam that should delight anyone.
First, I wanted to use the aluminum efficiently with as little waste as possible. That stuff is quite expensive, so its wise to be thrifty. The supplier I found that had reasonable prices on tubing sold it in 6 foot lengths because it was more practical to ship it that way.
Second, I wanted to have a fairly quiet antenna with decent forward gain and a good front to back ratio.
Third, It needed to be simple enough to build so that even I could do it.
Ok, here we go. Ill give a list of materials as best as I can remember what they all are.
(All tubing sizes are in 6 foot lengths unless otherwise noted)
1) 5 ea 5/8 tubing (tubing is from http://www.Cycle-24.com)
2) 5 ea ½ tubing
3) 5 ea 3/8 tubing
4) 1 20 section of 2 square tubing (.065 think) (From Metal Supermarkets)
5) 5 ea hose clamps for ½
6) 5 ea hose clamps for 5/8
7) 5 ea ½ X 2 ½ X 8 plastic cutting board (like youd use in your kitchen) (I actually used 3/8 think board I got a Wal-Mart)
8) 7 ea square U bolts 2 wide X 3 tall I got these from McMaster Karr I have gotten them from Tractor Supply and Ace hardware as well.,
9) 3 ea, Torroid cores for the RF choke balun. (from Digi-Key US and Digi-key UK) (You can also use a 1:1 balun or a coax balun)
Ό X 4 X 12 aluminum plate (for mounting the boom to a mast)
2 ea 2 (or 1 ½) U bolts for the mast mounting plate.
12 ea 1/4 X 3/8
Pipe U bolts (I
used these from Fastenal) (about 3/4 wide inside to clamp the 5/8 tubing
to the cutting board)
(You can also use screws and nuts to fasten the elements to the insulator, much cheaper))
There are some important things to consider in order to make sure you get the elements cut and measured correctly. I left the 5/8 6 tube at 6 except for the driven element. The driven element I basically removed Ύ from the middle. All of the ½ sections I cut in half and measured and marked 32. I then took the 3/8 sections and cut them as follows. 1 cut in half for D1. The next two cut at 39, leaving 33. The 39 sections are for the DE and the 33 for D2. The next two I cut at 42 3/4 leaving 29 Ό. The longer elements are for the reflector and the shorter ones for D3. This leaves you with one piece of 5/8 aluminum Ύ long as waste!!
I took both ends of the 5/8 and 1 end of each of the ½ tubing and cut a slit about 1 deep so that when I set one inside the other, I could place a hose clamp over the cut and clamp the tubes together tight. (This design is so good, you can use self tapping sheet metal screws everywhere except the last section of the driven element and eliminate the cost of so many hose clamps.)
Take the pieces of cutting board and drill them for your 2 square (or round if using round tubing) and the u bolts for the elements. (The elements are all insulated from the boom) (the ones I got are a bit too large diameter bolt J )
Remember, you will have 2 clamps on each side with the driven element as it is cut. I used some fiberglass rod inserted into the center to add rigidity to the element.
I took the aluminum plate and drilled it to accept the boom and U bolts for the mast.
I then measured and marled the boom so I would know when to set the elements. Try to be as accurate as possible, especially with the D1 element as its distance from the driven element is what helps get the impedance at 50 ohms so it can be direct fed.
Get a piece of 9913 or RG8 about 10 15 feet long and place the 3 RCF torroids as close to the feed point as possible and secure them to the coax with electrical tape or heat shrink tubing. Connect the coax to the elements with stainless hardware as make sure everything it tight. Then install a PL-259 connector and a barrel to connect it to your feed line. This makes it possible to hook things up on the tower without having to walk to boom to reach the feed point. Once you have everything on the antenna, find the balance point and place the boom to mast plate there so the antenna will balance easily on the mast.
I also placed some hot glue in the ends of the elements to keep the bugs out.