Building a Six Element 6 Meter Yagi Antenna
Project by KD2DVL & KD2DVM
First some background:
My wife and I Just received our Technician ticket in April this year. We have both been in the electronics field for the last 35 years at various levels. While we were in class for our tech license we kept hearing about the six meter "magic band". When we started to put our shack together, it was decided that 10 Meter fixed dipole would be our 1st antenna. We quickly caught the bug for DXing and I started looking for 6 Meter antennas. We wanted to try and catch the summer magic. We found plans for a six element 6 meter antenna on Hamuniverse.com. This being my first antenna that I constructed, I am sure the seasoned Ham will giggle at some of my technique, be gentle.
Current Shack equipment:
- Elecraft K3
- Ameritron remote coax switch
- New Channel Master rotor controller. (Original tossed out years ago)
Tools needed or should I say tools I used:
- Plumbers pipe cutter
- Pop rivet tool and 3/16" diameter pop rivets of various lengths.
- Hand drill and a drill press because I had it.
- Basic hand tools
Collect some materials:
I started with an old Channel Master VHF TV antenna and rotor that has not been used in 20 years. I was really just interested in the rotor and the backbone of the antenna. I also salvaged the hardware that held it to the mast.
I carefully drilled out the rivets, to free the backbone. I needed to joint 2 of the salvaged backbone tubes and found that a short 16" piece of 3/4" copper pipe fit nicely inside of the aluminum tubes. I am not too concerned about dissimilar metals at this point. I used 1/4" long 3/16" diameter pop rivets to hold this assembly together. I carefully measured and cut this tube (the new backbone) to the length needed with my plumber’s pipe cutter.
I found some copper colored 10' length’s of 1/2" diameter aluminum tubing at my local salvage yard that will work fine for the elements. I also found some schedule 40 PVC pipe of various diameters and lengths. Additional surplus items: Plexiglas, 1/2" aluminum strapping, Stainless Hardware as needed.
Let's get started:
I started carefully measuring and cutting the elements using the pipe cutter.
I marked and drilled a pilot hole followed by a bit that would provide a sung fit when the elements are pushed into place. After installing the 1st element, I decided that the backbone was just too flimsy to support the elements. I found some schedule 40 PVC, which fits over the backbone to stiffen things up quite a bit. (Note: I used several pieces of PVC, but I would recommend covering the entire backbone).
The PVC pipe was pop riveted to the backbone using 1/2" long rivets.
If you are careful to line up the printing on the PVC pipe, you can use it for a guide for element placement. Verify the length and position of the element. Mark the exact center.
I started by running a bolt down thru the PVC, and the element, backbone etc.
I checked the continuity of the element to the backbone and I was not happy. It was time for another EC (engineering change). I cut and removed some of the PVC material directly over the element. Using a small strip of the strapping material, I formed it and installed it as shown below. Note: be sure sand or clean the spot where contact is made.
Now we have good electro-mechanical connection. Prepare and install all elements except the driver.
Fabricate the Driver:
Before you cut the driver element, add a couple 3" to the overall length of the element. Now find, mark and cut the element in half. I then flattened about an inch of the element, and drilled a hole to accept the lugs of the coax. I made this with some Plexiglas pieces and lots of silicon. But there must be some easier ways to do this.
Below is the finished driver with all of the layers Plexiglas and silicone.
Time to find the weight center of the antenna:
This is pretty straight forward. No matter how you plan to attach this antenna to the short mast, you need to fined the balance point and attach the hardware. I used two pieces of PVC, one inside of the other pop riveted together. I also reinforced this are with some aluminum channel.
The Ugly but effective:
As directed from the instructions, I cut about 14" of 4" PVC. I wanted this to end up on the short mast going to the rotor. I made 2 wooden plugs for each end of the 4" pipe.
Cut a hole in the center making a donut. It's large enough to be able to slide this barrel on to the mast, below the antenna. I painted them and used sheet metal screws to hold it in place. (I have never been told I under built something!)
I measured about 18' of Belden 9913 equivalent. After drilling 2 holes near the top, I ty-wrapped the coax to the drum and began winding the cable. If you look closely you will see a 1/4"- 3/16" diameter rope. This line was pulled tight in the middle of each winding. I did this to insure each winding was kept apart. I finished with 2 holes and a ty-wrap to secure the bottom of the windings.
Can't hurt, can it?
If you look closely at the picture below you will see the coax leaving the driver at the top of the picture and headed for the winding drum. I enclosed the coax with a braided shield. I did this because of the statement about keeping the ugly balun drum as close to the termination point on the driver. I grounded the mesh to the boom. Is it doing anything? Who knows?
Attempt to control the sag:
I let the mast extend up past the boom so I could add some non-stretch rope to help support the backbone and keep the elements inline.
Tuning the Antenna:
As suggested by several sources, we set the antenna pointing vertical on the reflector. I used some rope and plastic steaks to keep it in place. We used the ATU function on the Elecraft K3 to get these readings. The starting point was 1:1.8 we then trimmed 1.0" off each end of the driver element. Our second reading was 1:1.4
We thought this was close enough, so we stopped here. I cannot explain it but after we put in up the third and final reading was 1:2.8 we are ok with this due to the ATU function on the K3. When I was doing the initial SWR readings, I could not get far enough away from stuff (like the house for example).
A final shot of the 6 meter Yagi in a temporary spot:
We are quite pleased with the performance so far. This has been a fun project and I would recommend it.
KD2DVL & KD2DVM 7-16-2013
Qustions? Email KD2DVL (AT)
Editor note: This antenna was
build using the plans from this article