Ham Hints -
RFI Tips and
Support The Site
6 Band "CB
Special" Multiband Vertical Ground Plane
A quick and
cheap 40 thru 10 meter vertical ground plane antenna!
Want to make "Gold"
from a CB base station vertical?
Then you are in luck
if you want to build a cheap "6" band HF vertical
:Getting Started collecting the
couple of years ago, my XYL heard of a person that had some "antenna
stuff" to give away so she was very reluctant to tell me knowing
that I was usually not one to turn down a "good deal" when I saw it,
but, long story short, she let the cat out of the bag. I drove about
5 miles or so and there it was, a "gold mine" of aluminum tubing
just laying there to be panned.
Among the pile of "gold", I
spotted the base of what appeared to be an old "base station"
style CB antenna, you know, the ones that were about a half
wave or so long on 11 meters and had those fancy sounding DX
Not only did it have the original insulated
base and all that went with it, but there buried under all that
metal was the working end of it, all that aluminum telescoping
tubing! I managed to load up ALL of that "antenna stuff" on top of
and inside the car and proceeded home trying to evade the local
"county mounties". Enough of that CB talk! I am supposed to be a
story shorter, here is how I converted that old CB relic into at
least a 5 bander vertical ground plane for use on the hf
ham bands. Yes I know, I said 6 bands earlier, this may depend on
your setup and tuner. No, you can't get something for nothing. A
decent tuner will be required for this project.
(I used the MFJ
Now really getting started
with the help of "Murphy's Law":
The first thing I had to do since it had been
laying out behind my house for a couple of years, was to get it
apart and do some cleaning of all of the tubing where the sections
went together. The screws were extremely rusted and they were a bit
difficult to get out of the tubing sections. Then as Murphy's law
would have it, the tubing sections were stuck together; so with the
aid of a pair of good Channel Lock type pliers, apart they came
except for the bottom section that went inside the loading
coil?/matching portion of the base.
With much effort, I was
able to get the outer case "protecting" the coils
inside, pushed up toward the mounting bracket just enough to
see the coils.
Murphy stepped in...the coil cover had not done
The coils were in very bad shape having
been subjected to years of rain, dirt, corrosion, etc....so I just
took them out of the circuit by clipping a couple of the wires. At
the very bottom of the base of the coil cover, there was an SO-239
connector with a nut attached for connecting the coax
feedline. The nut would not budge much (rust) and the
threads were striped in the process of my trying to loosen
it....junk. I did not use this connector due to it's
I then used an ohm meter to make sure that there
was no continuity between the center of the SO-239 and the upper
aluminum tubing or to any other part of the existing aluminum or
mounting bracket...there was none, so the entire coil assembly in
the base was now "out of the circuit" so to speak and I was free to
use ONLY the tubing and the base mount assembly of the old antenna
for the vertical radiator of this project which was my original
The next step was to clean the area of the
tubing where the radiating sections went together with some fine
grade sandpaper down to bright aluminum. This went well and did
not take long. Murphy must have been taking a
About the length
of the vertical and the radials:
From ideas on other
projects like those of KL7JR and others on this site and on the web,
I had learned that to make this antenna work well on many HF
bands...the radiating portion of the antenna was to be of a
non-resonant length on any ham band.
I did some more
research on the web and determined that the length of 15 feet for
the vertical radiator should work well when the radiator was fed
against a few radials of the same or longer length and
with a tuner. I used 3 radials of equal length of about 15 feet of
#14 insulated wire.
So the next step was to put the telescoping
sections back together, adjust the length to about 15 feet from the
now non-existing feed point near the top
of the mounting bracket and secure everything with screws. I had sort of reversed the procedure by not having a
feed point ready, and this is when I saw Murphy looking over
my shoulder again! He laughed and walked
Now I had to come up with a feed point
on the bottom section of the tubing near the base so I could get the
radiator length right....get away Murphy!
I wanted to feed the
antenna with coax so now I had to come up with a way to
connect the PL-259 from the end of the feed line to a
non-existing SO-239 that I wanted to use!
As luck would have it,
there hidden within the pile of "gold" aluminum tubing, was an old
bracket from another "junker" antenna that contained not one,
but two SO-239's! Murphy must have taken a nap!
I cleaned the
old bracket containing the SO-239 with fine grade sandpaper and also
gave the SO-239 a good cleaning inside and out with an assortment of
small steel wire brushes, and then it was a simple matter of just
drilling a small hole or two for a couple of
small bolts to mount the connector bracket to the original
mount near the future feed point on the vertical portion of the
radiator. I won't
mention here that Murphy came back from his nap and
proceeded to scatter nuts and bolts
The hookup to the
The "tip" end of the connector was facing up toward
the top of the radiator just like I wanted it so it was a simple
matter of eyeballing the length of wire needed to connect the
center pin tip to the vertical section only a couple of inches away.
Oooops...now I have to drill another hole for the wire to wrap
around a screw on the
When I was finished drilling and adding the
screw, connecting the wire from the connector to the radiator was a
simple process that Murphy did not
Now I was finished......but that darned Murphy
was still around laughing at me!
I looked over my new prize of a
5 or 6 band hf vertical from top to bottom and wondered what I
had forgotten.....there must be something...the way he is
Yep, sure enough.....I had
forgotten to mechanically secure the
sections together with screws! Upon lining up all of the holes in
the several sections of tubing, I realized that all would not match
up......DARN! I looked over my shoulder.....you know who.... was
right behind me....DRATS! Out came the drill again....I finally
found some screws that should be OK to use and the correct size
drill bit, so I drilled the holes in each section for them,
then added the screws and tightened
I must be finished now! You guessed it.....the
radials were missing and Murphy was holding the wire cutters and the
Finally after measuring out 3 equal length
radials of about 15 feet each using #14 size wire and getting
them cut without "incident", I mounted them in three fairly equal
distance locations around the mounting bracket just below the feed
point! The angle of the radials was just random, no specific angle,
maybe about 20 to 30 degrees as a guess. angle...
Up she goes!
I now had a completed multiband
vertical that had to be mounted on a short mast and put up beside
the house . No problems there other than having to use new "U" bolts
on the mounting bracket and tie off the radials on the ends.
Don't forget to connect the feed line Don!
I used two
lengths of 50 ohm coax, one section about 25 feet long of RG8
connected to the antenna base, the other was about 10 to 15 feet of
RG58.....giving me a total of about 35 feet or so of feed line to
the shack location at the tuner.
Swr and resonance testing without
Using an MFJ 259B these are the results at
the end of the feed line
swr (R=55, X = 0)
swr (R=49. X = 10
28.400mhz 4.4:1 swr
(Notice the resonant point at 16Mhz...for some
strange reason about 2 weeks later, this frequency changed to the
bottom end of the 20 meter band around 14.00Mhz!
I have not had
the time to figure out why, but the antenna still works great with
ON THE AIR
PERFORMANCE. The proof is in the pudding!
Over a few days
of on the air testing in the low part of the solar cycle in
I have managed to make really good contacts every
time I operated with at least 5 8 reports, with most of them
being 5 9 or better on 40, 20, and 10 meters using 100 watts and the
The 40 meter contacts were late in the day.
meter contacts were late afternoon. All contacts above were
17 meter band- Received many reports of S9 plus...some
even S9 plus 20db over!
15 meters has been dead here for some
time but I managed to make a schedule with a local ham some distance
away, who gave me a good report on a test transmission.
was "dead" at the time of testing but I received a nice report
from the same local station several miles away that
usually only could read me about S5 or S 6 on a multiband doublet,
but received me much stronger on the vertical. I could hear him also
much better when compared to my Hustler 4BTV or multiband doublet.
He was using an Inverted V if memory serves. I did not check 12
meters on the air as I recall but I am sure it will "work" there
6 Meters...a plus discovered later....low
swr (R and X) but used a tuner with it....band dead. More
testing to follow.
The antenna and the
YAESU FT-107 running 100 watts really shined on 20
meters during this contact. I managed to break a HUGE pile up
with him and received the usual 5 9 report in TURKEY!
More DX Results (Updated
While tuning around 40 meters about 5 PM CST
in January, 2009, I heard a giant pileup on
I broke the pileup with one call using my
trusty Yaesu FT-107 and received a nice 5 7 report from I2VRN in
Italy. He was 5 9 plus about 5db running a 4 element yagi and
about 500 watts. I was running this antenna described in this
article and 100
Then the next day January 25, 2009 on 10
meters, received a nice 5 9 contact from a Florida station. I stoped
there for a while with on the air
More on the air testing coming as time
So...... I guess it "works" well for an all around,
"no money invested" antenna, but so does a paper clip to some
extent! This "paper clip" just happens to work much better and only
cost me some labor and some fun!
Final comments and suggestions:
impression of the base station CB antenna converted to use on many
hf bands using a tuner has been a pleasant and rewarding project for
me and the good thing about it was the fact that I only had TIME
invested in it and a few inches of wire, a few screws plus dealing
with Murphy while I used other peoples "junk" to make a
multiband hf vertical antenna that has worked around the globe,
coast to coast and locally!!
When using the MFJ 901B tuner,
the "6 Band" CB to 10 meters Multiband Vertical Ground Plane
tunes up nicely on ALL ham bands from 40 thru 10 meters giving
a great match near or at 1:1 swr on all the hf bands from
40 thru 10 meters. I found that 6 meters may be useable
It also allows me to "hear" 80 meters as
if I had an 80 meter dipole up. Also to my surprise, it does not
seem to be as noise prone as most verticals I have tried or maybe my
noise level has just been low lately.
I look forward to
more on the air testing as time progresses.
So to repeat my self, I guess it
Below is a drawing with
lengths that I used and the location of the connector
Total height about 27 to 30 feet
Modified SO-239 location and
bracket on base mount.
Original SO-239 connector is not shown at
bottom of mount.
Attach radials to any suitable point just
below feed point.
Main vertical radiator is totally insulated from mounting
bracket at both
the top side and the bottom although not
shown in drawing.
The original mast mounting bracket was used
and not modified.
The base coil assembly is used only for
support but has been cut out of the circuit inside the coil
some room in the rf spectrum for me....73 Don,
Feedback from other
This from Bob, KF7DRC
Using the idea from the project above, I decided to
just go ahead and put it up at an experimental configuration using
an Antenna Specialists 5/8 wave 11 meter (CB) all aluminum
The total length of the modified CB vertical
radiating element is 27ft. 6 inches with 4 each 9 foot radials.....
it tunes easily on 6 meters thru 80 meters and it will tune, but it
is a stretch, for 160 meters.
I removed the gamma from the original CB antenna and
went direct to the so239 for the vertical element, not much change
from the original 11m setup except for removing the gamma match and
raising the mast height another 10 feet approx. I am amazed it is
working this well.
I am getting excellent reports and hearing
things a new and totally inexperienced ham should not be so
fortunate to get, he he he.
KF7DRC, Bob cherokee376 >
hotmail.com (remove the > and add the
@ symbol and close the spaces
|Uniden 4 Inch Communications
4" Plastic Cone
Maximum Power: 12 Watts
Wire: 10 ft. cord
with , AWG 18 Plug Type: 1/8" or 3.5mm Plug
Frequency Response: 500Hz-5KHz (Tailored
to voice frequencies)
Includes ratchet type
mounting bracket & hardware