Hex Beam by K4KIO
Site publication date
12/2007
Converting the K4KIO Home brew Classic Five Band Hex Beam
to the New G3TXQ Broad Band Hex Beam
Converting my home brew classic hex beam to a G3TXQ broadband hex beam was fairly easy. And it was well
worthwhile in terms of performance. You can see that here.

Converting the classic hex beam requires only a minimal amount of materials. You will need:
•        12 feet of Max Gain 1 inch O.D. round fiber glass tube.
•        10 feet of 16 ga. Wire
•        75 feet of Kevlar/Dacron cord for tip spaces and structural support of the spreaders
•        The remaining materials can be re-used from the classic hex beam.

CAUTION! These guidelines are NOT applicable to the commercial HB5i Traffie hex beam. If you are planning to
convert the commercial HB5i hex beam to a broad band version, you will likely need different materials and the
fittings quite possibly will be different. So proceed with caution.
Basically, you will be expanding the size of the hex beam from 19 feet in diameter to 22 feet. You will use the
existing base plate and center post with driver terminals unchanged from the classic hex beam. The same
wires will be used with some cutting and splicing, re-arranged into the new shape. A single tip space between
each driver wire end and each reflector wire end will replace the two end spaces used in the classic hex beam.

Adjusting the shape and symmetry of the wires and spreaders is easier with the new broad band hex beam
than with the classic because of fewer tip spaces and no anchoring of the reflector at the center post. A
continuous loop for each band is formed by the larger reflector wire, the driver wires and the two tip spaces.
Once this is installed with its clamps to the spreaders, adjustments are quite easy.
Classic
19 feet Diameter
G3TXQ Broadband
22 feet Diameter

Here are the seven steps to follow after mounting the classic hex beam on a stand:

1.         Retrofit the spreaders
Expand each spreader from 126 inches long to 144 inches long by adding a 24 inch piece of 1 inch O.D. fiber
glass round tube. Do not remove the spreader from the base plate; just loosen all the wires and then cut the
spreader while mounted, add the new piece in and then use Liquid Nail adhesive. Let this dry a couple days
while working on the wires. Paint it. Click on the sketch to the right for details of the new spreader layout.

2.         Retrofit the wires
The classic reflector wires should be removed from the beam and soldered together. Then the combined wire
should be trimmed to the specs below. The driver wires can be left on the terminals but each half must be
increased a small amount by soldering a piece to it to the specs below. The end spaces must be replaced
with new tip spaces. Use the old connector blocks for this and 0.075 inch kevlar/dacron cord to the specs
below. Remember that the specs below are the distance for the wires so you need a little more cord to allow
for knots

Band                                                                          20                  17                   15                     12                    10
Total Reflector (in.)                                                412                321                274.4                232                204.4
1/2 Driver (in.)                                                         218                169.5             144.5                121.7             106.8
Tip Space (in.)                                                          24                  18.5               16                      13.5                12
Post position above baseplate (in.)                     42                  20                   14                      10                     6
Clamp position from base of spreader             138                100                  83                      70                   61

3.         Center post and terminals
If there are Reflector terminals on the center post, these can be removed or left in place but they will not be
used in the broad band hex beam. No other changes are needed in the center post. If you have retrofit the
spreaders as recommended here, their curvature will be the same towards the end and therefore the post
spacing for terminals will be the same also. At least that's how it turned out for me.

4.        Re-locate the clamps on the spreaders to the locations specified in Step 2. above. Don't over tighten as
these will be adjusted later.

5.        New cords
You will need four new radial Kevlar/Dacron cords from the center post to each of the four spreader ends as
shown to the right. These permanent cords should be measured to 128 inches and attached to the clamp
locations, not the spreader ends. (Use a connector block on these cords so you can adjust them precisely.)
The other two spreaders will be pulled up by the driver wires that will be firmly attached to their clamps on the
spreader ends. You will also need two cords between the same two spreaders as shown. As with
construction of the classic hex beam, it will make the job easier if you start off by establishing the shape of the
hex beam using 12 temporary nylon cords 130 inches long as shown. Hook these temporary nylon cords in
the ends of the spreaders and over the lip of the center post.

6.        Install 20 meter wires
By expanding the spreaders using the thicker fiberglass, the shape of the more curved portion of the
spreaders is maintained as it was with the classic hex beam. Therefore, the center post terminal locations are
the same and no new work is needed on the center post. You are now ready to start stringing the wires.

Start with 20 meters and try to be as precise as possible as these wires, tip spaces and cords will determine
the shape and symmetry of the new hex beam. Follow the specifications here for that. For 20 meters, you will
need to fasten the wires to their clamps on all six spreaders because these wires form the perimeter of the
hex beam and you don’t want them slipping around in the wind lest it skew the shape of the hex beam.
Therefore, you will want to use the connector blocks as shown on the 20 meter wires only.

When the 20 meter wires and tip spaces are installed begin adjusting and tightening clamps and connector
blocks until you have achieved the “perfect” hex beam shape. It will look just like the classic, only a little larger.
Start with the inside driver wires. Get them taut, fastened to their spreaders and then work around to the other
spreaders in turn. Remember that the precision of the radial cords and the clamp locations will ensure that
the wires wind up horizontal and level with each other. When you are satisfied, tighten the set screws in all the
connector blocks.

7.        String the other bands
When you are finished with 20 meters, install the other bands’ wires to the center post terminals but allow
them to run loosely in cable ties at all the spreaders. Pull the clamps up the same amount a little at a time
until most of the slack in these wires is removed but do not strive for tautness as it is difficult to achieve
without distorting the overall shape and does nothing for the performance anyway.

The other bands’ wires will be allowed to slip loosely in the cable ties connected to the spreaders as in the
classic hex beam. Don’t be tempted to use connector blocks at the spreader clamps of these other bands; I
did this at first and discovered that they seriously de-tune the wires. In fact, they de-tune the 20 meter wires too
but not as much because of the length of the 20 meter wires and in any event, this has been factored into the
design lengths of the 20 meter wires.

You are done!  
Click to enlarge
Building the G3TXQ Broad Band Hex Beam
Other Hexbeam Sites

G3TXQ Hexbeam

WI4USA Antennas
The commercial G3TXQ
Broad Band Hex Beam

Yahoo hexbeam user group

Hex Beam by K4KIO (Classic)