Build an All Band HF Air
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1:1 Choke Balun
THE "UGLY BALUN"
(e.g., a dipole or driven element) to an unbalanced
line such as coax which
is not balanced, thus the name, Balun. The 1:1
choke "balun" is not actually a balun. It's function is to
help eliminate rf currents from flowing on the outside of coaxial
cable using the principle of choke action. Another "name" for it is
the air choke.
balun's purpose is to allow connecting a balanced,
In transmitting antennas, this is accomplished
by presenting a high impedance (resistance), to RF currents flowing
outside the coax shield. This forces currents in each side of a
driven elements to be equal. This is especially important in beam
antennas because it prevents distortion of the beam's pattern caused
by unequal currents in the driver(s). In a simple dipole, the balun
that the dipole, and not the feed line, is doing the
When you connect center fed antennas, like dipoles,
V's, triangles, yagis, rhombics, loops and so on, to coaxial cable,
unless care is taken, it is not difficult to end up with feeder radiation. Not only can the loss in
power be quite significant, but the radiation characteristics of the
antenna system will also be seriously compromised.
terms, it won't be what you are expecting from the pattern of your
As the feedline becomes part of the antenna, currents
can flow from the line into the mains and on TV cables, metal masts
and yagi booms, causing a variety of EMI problems that can be
very difficult to trace. Frequently these problems are simply due to
unbalance - and the solution is the humble air choke.
antenna system is fed at center with a parallel conductor line
(provided that correct installation procedures are followed) balance
will be maintained, USING A BALUN, with currents in equal and
opposite phase canceling each other out.
When the connection is to a coaxial cable, WITHOUT A BALUN,
this cannot occur because currents flowing inside the cable from the
connection to the inner conductor are separated from those flowing
on the outside from the connection to the shield, and the result is
unbalance causing feeder radiation. However, if the two electrical
circuit elements (antenna and coaxial cable) are coupled using a
balan, balance will be maintained.
Enter.....The Ugly Balun!.....
An Inexpensive, High-Performance, Ugly
50 ohm Balun
"Building a no-grief 1.8MHz to
30MHz 50ohm-balun is easy.!"
"No costly ferrite-cores are needed,
just a short length of 3 to 5 inch size plastic pipe, about 25 feet
of 50ohm coax plus some nylon cable ties.
coax is best for this application because foam-dielectric has a
tendency to allow a change in the conductor to conductor spacing
over a period of time if it is bent into a tight circle. This can
eventually result in voltage breakdown of the internal
The required length of the plastic pipe depends
on the diameter and length of the coax used and the diameter of the
pipe. For RG-213/U coax, about one foot of 5 inch size pipe is
needed for a 1.8MHz to 30MHz balun. For 3.5MHz to 30MHz coverage,
about 18 to 21 feet of coax is needed. This length of coax is also
adequate for most applications on
18 to 21 feet should cover
all of 160 through 10 meters.
The number of turns
is not critical because the inductance depends more on the length of
the wire (coax) than on the number of turns, which will vary
depending on the diameter of the plastic pipe that is
The coax is single-layer close-wound on the
The first and last
turns of the coax are secured to the plastic pipe with nylon cable
ties passed through small holes drilled in the plastic
winding must not be placed against a
The name of this simple but effective device is a choke
Some people build choke-baluns, without a plastic
coil-form, by scramble-winding the coax into a coil and taping it
together. The problem with scramble-winding is that the first and
last turns of the coax may touch each other. This creates two
complications. The distributed-capacitance of the balun is increased
and the RF-lossy vinyl jacket of the coax is subjected to a high
RF-voltage. The single-layer winding on the plastic coil-form
construction method solves these problems since it divides the
RF-voltage and capacitance evenly across each turn of the
Credit for this article goes to AG6K,
Rick Measures and was edited from a Pre-copy version of another
article titled "A BALANCED - BALANCED ANTENNA TUNER" published in
Step by Step Sequence of building the "Ugly Balun"
incorporated as a center insulator also using PVC by
KC7AVA. (Sequence is from left to right and down
4" PVC and
Winding the 21' of
Securing coax with cable
Adding a solder
Connecting the coax to
Time to wire up the
Unbraiding the dielectric
The KC7AVA Ugly Balun –
ready to go!
See his entire construction article and his story
Back on the Air" at the link here!
more "Ugly Balun" photos, ideas and installations sent in by
Here are examples in the pictures
below using cable ties on PVC pipe forms which work well also. Your
(Imagine the coil form is removed). Pictures are showing
how to secure the coils together. Do not let the first and last
courtesy of VE7AVV
Picture above courtesy of KC2NXV (now N4NYY) shows using
2 pvc couplers joined and glued using about 2 inches of 4 inch PVC
pipe, so the couplers would adhere and be
Balun" ideas from DAVE THOMAS, M3RUH
The Dave Thomas,
MW3RUH BOTTLE SPECIAL!
Dave uses a plastic drink bottle as a form. He
S0-239 in the bottle cap and antenna connectors
on the other end!
NICE TIP DAVE!
Photos courtesy Bill, KI4PCB, using 4 " PVC
Notice the screw terminal block used for
KI4PCB "Ugly Balun" on the
N7ATA "Ugly Balun in Real Life"...thanks
Courtesy of G4APL (see info
Courtesy of G4APL (See info
Courtesy of G4APL.
(Air choke used on Mosley Mustang Mark3 3 element 10,15, 20 metre trapped
Choke Balun inline with the GB7CIP Pactor Trapped HF Ground
Another Ugly Choke Balun by
has brought together some excellent examples on how to construct and
build Choke Balun in the pictures above and the information below to
share with us:
Paul decided to
build two or three of them, depending on what material could be
found in the shed.
The idea was to
add a balun to the HF beam, a Mosley Mustang Mark3 3 element 10,15,
20 metre trapped yagi. This is fed with co-ax and has the Mosley
earth strapped at the feed point. The beam has been adjusted for the
low end of the HF (High Frequency) bands.
Paul had used a
commercial balun in the 1970’s before and burnt this one out. It was
supposed to be rated to 1 kilowatt pep. (peak envelope
information material from the instructions for the "Ugly Balun"
above, it was time to see what was in the
length of 4 inch drain pipe was located that was left over from the
90 foot of drain pipe laid underground that carries the RF cables.
Also found a 2 inch piece of down pipe.
length of 4inch diameter PVC drain pile
18 foot of
Having got all
the required tools out, it took Paul and hour to build the Ugly
Choke Balun as pictured above.
The HF Balun is
attached vertically to the Stub Mast at the Mosley Mustang Mark3
Paul was very
surprised with the results. Testing the aerial and Balun with 250
Watts the standing wave was surprisingly good.
Never seen this
beam produce these results before!
Now to do some dxing and
see how the aerial performs.
Hope the above is of use to
from ZL1ALZ, JOHN from New Zealand!
"Ugly Balun" construction
used on a 40 meter vertical!
Closeup of the
ZL1ALZ "Ugly Balun"
The VE2ITZ Balun
with Sloper Antenna!
Never had such an easy
time at tuning the sloper antennas with the "Ugly
By the way; the balun consists of 20 feet of coax
wound around a 2 and a half inch diameter plastic bottle. I then
proceeded to put gaffer tape to hold it in place.
Cheers and 73 de VE2ITZ in Montreal,
"Ugly Balun" installed on the A3S 3 Element Beam
at the KO4MAX QTH!
This update was compiled
from various emails:
"Hey, we don't think it's
deserves the credit just for putting up with
I wanted to
add (in this update), that 21 feet is the length of coax used
in the construction.
We put the
antenna up on a Sunday afternoon, and it was sketchy to say the
tuner in his Icom 746 Pro kept engaging automatically (even
when it was turned off).
I knew it had
to be coupling with the feed line.
So, I showed
him your Ugly Balun page and then the Hy Gain manual I have, which
calls for 12 turns 6 inches in diameter.
He read the
Cushcraft A3S/40m manual which states 8 turns at 6 inches in
debate we went with your design. See photos
the Ugly Balun.
antenna works and it works well.
day on the air (Tuesday) he sent an email informing me that "it
rocks" which is a quote.
He also says
it's a big improvement over the dipoles he had on those
and the warc bands is all that is left in his
those dipoles for those bands.
Thank you for
your contribution and website!
We found the
Ugly Balun to be a huge help when it came time to stop the feed line
it gives this big A3S/40m (10-15-20-40m 3 Element
We installed this at KO4MAX in South
Florida. See photos below:
Update 04-2011....showing stainless steel
clamps in final installation
used 4.5 inch bolts through the half pipe (split in two
We inserted 4 inch stand-offs and bolted the 4.5
inch PVC to the half pipe.
We used tie wraps for a temporary
installation (During testing).
Stainless steel clamps were used
in final installation.
We plan to install U-bolts to permanently
mount the assembly to the mast pipe.
No more coupling
with the coax after installation.
Tested with the MFJ-269 Pro
Nearly perfect on all 4
This thing, over 2 years later, still working like a
This installation should provide many years of
Came down off the tower and made our first
contact with Italy IZ5ILF - Max
Thanks for the ugly
TL7VE - DX8FW
Balun Pics below submitted by K8CPA. "Ugly Balun"
mounted on base of tower.
The work, including the Balun winding was done
by my friend Matt, AC8AC.
The Antenna is a homebrew G5RV, that
73 es gud dx
"I want to thank
you for the usefull information and different
examples on your
web page, I could understand and build two 1:1 chokes
for my 5BTV
phased verticals, I also helped other local hams with
project. They work!."
73 de Eduard
Below are some ideas from Kelvin, G4ZTD
Balun shown attached to vertical antenna
Antenna connector end shown
Balun shown mounted to gray pipe
I used 21 feet of rg58 on 4 inch drain
pipe, I used clear 3mm plastic sheet cut to fit in the ends,
glued these in using hotmelt, then at one end I fitted an so239
connector and the other end has terminal posts to connect to the
antenna and ground. You will notice the vertical slots cut into
the brown tube. These are to allow any water to run out of it.
The gray pipe was glued to it so I could attach it to the pole
with cable ties.
Funny thing is it looks quite cool.
have tested it on 20 mtrs 14.230 (SSTV) and the swr meter hardly
Many thanks for the info you gave on the site. Best 73
The WA6GUZ Installation!
Nice installation on a vertical by WA6GUZ!
"I built the "ugly balun" for my TWIN LEAD, 80m
MARCONI ( by William Orr )
Balun and antenna operating excellent
!" VK4JAO- Arno
After reading the
article on the Pro's and Con's of the "Ugly Balun", I decided to
make one and install it on my home brew 3 Element 17 Meter
Yagi.... after all one home brew deserves another
Looks like it is
going to work out just fine. I used 21 feet of 9913 Flex around
a 3 inch schedule 40 PVC pipe.
The dipole has a
split driven element so feeding it was just like feeding a wire
dipole. Tuned up ok but may have to adjust the DE for a little
better standing wave ratio, but all in all its a thing of
Ugly is just a state
Catch ya on the
This just in from
Frank and his ham friends calls it his "bee-hive"
I made my first
home-brew 20M dipole late 2010, and quickly found myself faced with
a challenge. Too much RFI into the shack. On a local
technical net, I mentioned my woes and attempts to eliminate cooking
myself without relocating. More than one ham recommended the
"UGLY BALUN". My first thoughts showed my ignorance as I
didn't take it as a serious solution. But glancing around the
shack I saw I had enough to try it anyway, and the opportunity to
make another antenna was appealing.
Boy, am I glad I
did! A quick GOOGLE search led me to the Hamuniverse.com
site and this Ugly Balun article. Adding the
air-wound common-mode choke (Ugly Balun sounds so much better!) It
reduced my field-strength meter swing from 10+ to barely 1 anywhere
in the room. Now, I too recommend it to anyone using a
dipole. Ugly doesn't mean stupid! In ham radio lingo, it means
See photos below.
How I built the "bee hive" ugly
I used a large pump-type shampoo bottle,
about 5" tall, 4" diameter, upside down. After
measuring and tapping holes for my tie-wraps, I wound about 20' of
RG8x around the plastic bottle, and used a PL-259 connector on one
end to bridge with the feed-line. The other end of the coax
was center conductor to one side, shielding to the other, making the
dipole connection points. I used nuts-n-bolts and a couple of large
washers on both sides of the bolts for stress-relief on the plastic
and to secure the antenna legs. This assembly allows me to
remove the balun from the system easily and add/remove bands with
little effort. A threaded brass loop from an old table-lamp
lets me use a simple double-ended snap hook to a eye-bolt screwed to
the eve of the house. I finished off the project by applying a
generous amount of liquid tape to anywhere that water could seep
Now I'm happy as a (uncooked!) clam. (I should'a said
What a superb and simple solution. Thank
This is made from 21
feet of RG213 Coax and a little bit extra to help connect the balun
to the antenna.
I have decided to
mount the choke on a wooden fence panel as illustrated in left
It was too fiddly getting up to the CP6 coaxial
mounting so I just patched into the coax.
Balun mounted on fence below
I could never
tune 80m but now I can. There is
considerably less noise than before.
I am so
impressed I have made another one to take portable with me for
when we attach large verticals to portable masts. Hopefully this
will help some of the RF feedback issues I have been
Here is my new "choke balun" in the 2
images above for the Diamond CP-6.
I can now tune better. 80m came
Less background noise all over the
I feel happy to try the Ugly
73, Bert EA8AGF
Powered by Ham
Email Concerning the
From Russ Wilson
"Don. I built one
of the "Ugly Baluns".
I was using it on a dipole for 80/40
I had some TVI without the balun, so no doubt the
feedline was radiating.
With the balun attached, the TVI
completely disappeared. I built a second one as I had the same TVI
problem with an R7. The balun cured this as well. I can run my
linear now with no problems as all.
So I appreciate your
expertise and your article."
CHECK OUT RUSS'S ANTENNA PROJECTS ON THIS SITE:
20 METER MINI BEAM
20 METER V BEAM
Photo Credit VE7AVV taken with permission
from his project at:
Balun Replacement Project
See the rest of his site
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