2 Meter 7 Element Yagi with a
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Based on the 2 Meter Beam Project by
It's hot weather in Texas in July and Larry
Parker, N5WVX, shows us a novel way to make these
"cool" elements for a 2 meter Yagi and also his method of
building a gamma match. This antenna was designed for the low
end of 2 meters and Larry shares his fun with it with everyone
who loves homebrewing antennas. Here is a "Cool" 2 meter Yagi
designed to give you lots of fun on these hot summer days. Grab a
glass of iced tea.....with a "Twist".
We call Larry's 2
meter Yagi project.... A Yagi with a "Twist".
(Hot chocolate can be used in the winter...hold the
See the "Twist" above? Cool!
You will notice in the closeup above that the element
It is made from #10 SOLID copper wire that is
twisted. If you don't have ready access to tubing for small Yagi
elements and have plenty of #10 wire laying around, then try
Larry's method of making the elements for a Yagi. Read on to learn
how he does it.
1. 12 PIECES OF 10 GAUGE COPPER WIRE 48"
LONG BECAUSE WHEN YOU TWIST IT TOGETHER IT SHRINKS>>> IF
YOU PLACE THE TWO WIRES TOGETHER AND PLACE THE END IN A VICE AND USE
A DRILL, YOU CAN TWIST THE WIRE INTO A SPIRAL.
TRIM FINAL LENGTHS
AS NEEDED FOR EACH ELEMENT AND MOUNT TO BOOM.
USE CAUTION WHEN USING A DRILL TO MAKE THE TWISTS! A
GOOD PAIR OF SAFETY GLASSES SHOULD BE USED IN CASE THE WIRE COMES
OUT OF THE VICE WHEN TWISTING...USE A VARIABLE SPEED DRILL AND BE
IF YOU PREFER, USE A
SCREWDRIVER OR OTHER METHOD TO GET THE TWISTS!
2. 3/8 " COPPER TUBING 1 1/2 FT
LONG..THEN FLATTEN TUBING TO BE CUT AT LEAST 1 1/2" LONG EACH. THIS
WILL BE USED TO SOLDER OVER THE ELEMENTS WHEN ATTACHING TO THE BOOM.
SEE PICTURE ABOVE.
A SHORT COPPER STRIP CAN BE USED AS A STRAP
ACROSS THE ELEMENTS FOR SUPPORT AND SCREWED TO THE BOOM AS IN
PICTURE ABOVE. NOTICE THAT EVERYTHING IS SOLDERED WELL.
3. YOU NEED 12 OR MORE SHEET METAL
SCREWS. USE TWO ON EACH ELEMENT AS SHOWN IN PICTURE
4. GAMMA MATCH--YOU NEED PIECE OF 3/8"
ALUMINUM TUBING 5 1/2" LONG.
FLATTEN ONE END 1/2". THE
EASIEST WAY IS TO PUT IT IN A VICE & SQUEEZE.
TAKE A PIECE OF COAX 9913..... STRIP OUTSIDE
SHIELD OFF BUT LEAVE PLASTIC INSULATION ON CONDUCTOR WIRE.
IT SHOULD BE 7-8"LONG.. WHEN YOU STRIP WIRE LEAVE AT LEAST 5"
OF INSULATION ON AND STRIP THE REST.
standard gamma match and Larry's version below
(Typical gamma match
Larry's Gamma Match
In Larry's version, he inverted the gamma match both
electrically and physically as shown in the pictures below showing
the sequence of construction.
Materials layed out for use.
All lengths have been cut to final lengths. The SO-239
has been mounted in a small "L" bracket made from
aluminum with the appropriate hole drilled out and secured
with short bolts and nuts. Note the black insulation over the
conductor. This, along with the center conductor of the
coax, forms a tuning capacitor when inserted inside the tubing
below it in the picture. You will also see a small adjustable copper
bracket which doubles as a spacer and support that has already
been bent to fit the coax center conductor and the 3/8 inch tubing.
The idea here is to make it where it will slide for SWR adjustment
later and then can be securely tightened on the driven element end
and the gamma tubing.
Step 1. "L" bracket mounted
to driven element with a bolt of proper
You should also notice the very long bolt extending thru
the driven element.
This bolt is used to mount the driven element
to the boom.
Cut off any excess length after mounting on
The bolt length will depend on the diameter of your
Step 2. 3/8 inch tubing with
flattened end mounted to center pin of SO-239. It is difficult
to see in the picture, but a hole is drilled in the end of the
flattened portion of the tubing and a screw or small bolt was
used for the mounting. Don't over tighten. The end result is that
the tubing is insulated from the outer shell of the SO-239 by mounting it on the
The spacing between the gamma match
assembly and the driven element should be about 1 1/2
inches after completion.
Step 3. Showing the
insertion of the coax assembly inside the tubing.
Also note the
wedding ring on the left hand and the pin and pad nearby.
pad is used for "excuses" for the XYL as to why he is not mowing the
Larry will have a page full of excuses when he is
The antenna should work fine, but will the
Step 4. Final assembly of gamma match mounted to the
Larry has gone
for some lemon for his iced tea! That list of excuses is
You can use the gamma match mounted
either on the top or bottom of the boom. Your choice. See picture
MATCH 5 1/2 " LONG 1 1/2 " SPACING FROM DRIVEN
Tune by sliding the coax inside the tube and
adjusting the sliding clamp back or forward toward the boom for
lowest SWR. The two will interact so when you tune one for lowest
SWR, then tune the other adjustment.
You will eventually reach
the lowest setting.
Finished antenna in the
Note - Picture above shows 7 "twisted" directors and
the driven element with the reflector out of frame on a 9
element version. You can use as many directors as you want, but
maintain the 16 inch spacing and decrease the length of each
successive director by 1/8 inch.
Larry used a length of tubing
for the driven element in the picture above for more stability with
the gamma match attached.
(7 Element version not drawn to scale)
Note: All lengths are in
1ST ELEMENT, THE REFLECTOR ON LEFT IN
DRAWING ABOVE, IS 40",
2ND ELEMENT 37 7/8" (The
driven element) DE
3RD ELEMENT 36, D1
4TH ELEMENT 35 7/8
5TH ELEMENT 35 3/4 D3
6TH ELEMENT 35 5/8 D4
35 1/2 D5
SPACING IS 16" BETWEEN EACH ONE
Final SWR reading
SWR 1.2 ON 144.200-145.600
Running the lengths and spacing using the Quick Yagi
Program by WA7RAI yielded these results based on an element diameter
of about 1/4 inch.....
Gain - 11.66 dbi (thats about 9 dbd
F/B ratio - 17.00
There are many ways to put together a Yagi. There are
also many ways to use different types of materials such as hollow
aluminum tubing, solid aluminum tubing, and also wire supported on
wooden dowels, fiberglass rods, even small diameter PVC, etc for the
elements and to build a gamma match.
This article and project
shows 2 different ways of building and attaching a gamma match...it
is your choice to choose which is best for your building
experience...either will work just as well as the other. Use your
own ingenuity and "ham engineering" to make one work for you.
Larry has shown us a cool way to make the elements with wire and
much stronger than just using one single wire and his method works
for him. Now it's your turn....get building and experiment! 73
Email Larry here for
questions ~~~~~ larry_969 (at) hotmail.com
Note: This is a spam
fighting email address above. Make sure you reinsert the @ sign in
the appropriate place in his email address.
Many thanks to Larry, N5WVX for
sharing his "cool" ideas with