| History | Baseplate | Centerpost | Spreaders | Wires & cords |
| Building | SWR & tuning | Do's & Don'ts | Installation | Reference |
Lately I moved to another QTH. Because I can't install a big tower right now,
I picked up a used 9m tower. An iron tube
will give me another 3m. My goal was to install an antenna with a small
footprint, with some gain and directivity. If possible 5
bands and the antenna should be able to handle QRO (800w).
Because it's temporary I wouldn't spend to much money, so the hexbeam seems to
be the ideal solution.
I did some research on the internet and found several websites that helped with
designnotes, hardware tips, ....
The word got spread in the clubstation and there was a very positive drive to
help and to review the ideas.
Serveral chatsessions with co-builder, ON3TD en Patrick, ON4CLQ (hardware
expert) resulted in a "let's go" early
November. The goal is to build it First Time Right. It should be broadband
and able to survive 90km/h wind.
I had lot's of ideas, but there's a point where you have to start building.
One day I received a mail from Patrick, ON4CLQ, he
build the baseplate, wow what a surprise. The baseplate is aluminium, the flence
is Inox. Strong, light and well built. Thanks
again Pat. Don't forget to drill a hole in the baseplate for the coaxcable.
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Baseplate (under) |
Baseplate (support centerpost) |
For building the centerpost you need a PVC tube of 120 cm and
4cm in diameter. drill 10 holes to install the srews which have to
support the dipoles. The angle should be around 60degr. but is not critical.
Here comes some math in placee. If your PVC tube is 40mm diameter, the perimeter
is 40mm x π (3,1415) = 125,66mm
60degr means 1/6th of a circle. So pulle a straight line on your PVC tube. The
other 2 lines (+30° & -30°) should be at
125,66/12 = 10,5mm.
I used M4 20mm inox screws. Here you find the
distances from the screws to the baseplate.
Here begins the serious part. Before you start (trying) to insert the screws
make sure there are no woman, children or guns around.
I made a usefull tool from an iron coathanger which helped me a lot and saved me
from some extra grey hairs.
After stumbeling for another 10 minutes I putted a mark on the coathanger to have
an idea of the distance. When this trick was
applied, all screws where fixed within 5 minutes.
When the screws are in place you can start to built the coax feeder. Foresee at
least 2 hours to accomplisch this job. You need
1,2m 50ohm coax, 16 cable shoes, a good cutter, and a solderstation.
Because I want to run QRO I used RG213. If you plan to stick with 100W, RG58
will do just fine.
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Holes are drilled, the "easy" 10m screws ones are fixed |
Tool to fix the screws |
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Finished...yes.... |
Foresee about 2 to 2.5 cm for easy installation |
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Coax connections in detail |
Centerpost finished |
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Adding PVC for a perfect fit |
Top of centerpost, used to attach support wires |
Spreaders can be made of several materials, some use fiber glass
tubes, others use bamboo but most popular here in europe
are the crappy fishpoles. They're quite cheap, I paid 5€ each. I consider looking
for a 5m pole, so you gonna have to remove
the topend and eventually remove a part at the base. When you slide out the
elements make
sure they fit pretty tight.
To keep the fiber elements fixed I added silicone base glue (TEC7) on all joints.
As said before, these are crappy fishpoles and they might be the weakest link of
the antenna. Try to find some alu-tubing to
re-inforce the base of the fishpole. Forsee about 30cm. I as lucky to find a
perfect fit....an old destroyed A3WS did the job.
Then cut the fishpoles on the right length. I'm building the broadband version,
the min. length is 353cm, I took 355cm.
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6 identical fishpoles |
Remove unneeded parts |
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Add silicones to all joints |
reinforce the crappy fishpole with alu-tube (30cm) |
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Make sure they all have the same size |
I used this tool to cut the fishpoles. |
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Support for the S-hooks. |
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A couple of months ago I found some nice lengths 1,5mm2 and
2.5mm2 for a good deal. I Decided to use the 1.5mm2 to reduce
weight and windload. Make sure you have the right lengths. Measure twice, cut
once. I advice to cut the reflectors first. If you
make a mistake you can reuse/recuperate the lengths to cut the drivers.
All reflectors where pre-assembled with cable shoes and tip-spaces.
Not affecting the performance, but needed to complete the project are the
support cords. You need at least six (from top spreader
to centerpost) but I made 12 pieces. The 6 additional perimeter support cords
have to be looped over the ends of the spreaders.
The length of each cord is 328cm, S-hooks included. It's very important to use
UV resistent cord with a low stretch factor.
Some builders use the 20m dipoles & reflector as perimeter support, but I didn't
want to stretch the VOB cable.
For the tip spaces I used the same wire as the support cord. The length of the 5
tipspaces is available in the table at the bottom
of this page. Make sure you add at least 10cm, it allows you to run the wire
twice through the electrical connector for more
security.
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Dipoles & reflectors |
Connections tip space & reflector |
The length of all wires & tip spaces.
Remember, the driver consists of 2 sections (dipoles) and the reflector consists
of one section.
All sizes are in centimeters. 2,54cm = 1 inch.
| Band | Freq | Length 1/2 driver | length reflector | tip space | distance screws above base plate |
| 20 | 14.150 | 553,7 | 1046 | 61 | 15 |
| 17 | 18.100 | 430,5 | 815,3 | 47 | 25,5 |
| 15 | 21.250 | 367 | 697 | 40,5 | 35,5 |
| 12 | 24.950 | 309,1 | 589,3 | 34,3 | 51 |
| 10 | 28.400 | 271,3 | 519,2 | 30,5 | 106,5 |