Hexbeam
construction.....
A few friends of mine started building Hexbeams. Now living in the
inner city where the lot is only 5 mtrs wide, a hex might just be the way of
getting a decent signal out! So I have started to build a
hexbeam.
Gerald, VK6KTN, has welded 6 M10 hex bolts onto a 300mm length
of 42mm steel tube for me. This will form the hub..
Onto the spokes of the hub I have put 200mm
long pieces of 12mm OD aluminum tubing.
Into
the 12mm aluminum tubing I will put 10mm fiberglass rods. These have been
sourced from a local stock agent. They are used for electric fences and
come in lengths up to 2mtrs. They are due to arrive around the 20th of
May.
NOTE: The inside diameter of the 12mm aluminum is
a about 1mm too small to fit the fibreglass rods. I drilled them out
using a 10mm drill. Worked fine!
I will update this page once that has
happened, but in the mean time I will cut the elements for 10, 12 and
15.
The lengths
are:
Driven
Reflector
15
363.5
739
12
305
622
10
273
555
All dimensions in cm.
Remember: the Driven
element dimension is for ONE side of the dipole...you will need to multiply that
by 2!
I have calculated that I will need about 2M length on the spreaders
for 15M...but that's a very rough calculation. We will see what happens
next week in reality...stay tuned!
Saturday 19 May
2007...
So here we are ready to start assembly of the
Hex...
During the week I received the 6 x 2M fibreglass silicon filled
poles. These are available from any good rural outlet. They are used on electric
fences and come in a variety of lengths. Prices vary from $4.50 to $6.50 per
length.
I have also purchased a 1.5M x 40xx PVC pip. This will sit over
the hub and has the element guys attached and the actual elements.
As
this will be a semi permanent solution, I have opted to use stainless steel hose
clamps to hold the elements onto the spreaders. Some of the techniques used in
this antenna are the same as those used on the Spiderbeam. I do have a quantity
of the Spiderbeam insulators coming that I will make available if people want to
purchase them. They are perfect for a Hex!!!
As you can see, my yard is small! What you see here
is about 80% of my backyard! Enough space to put a car and that's about it...and
a 1MM Hexbeam!
This photo show the spreaders on the hub and the supports
for the spreaders. I used Brickies line...but it doesn't come in black!
:-(
The PVC is 40mm.
Sorry the picture isn't in focus, but the camera didn't
like being that close!
The other pic shows how I have done the element
spacing. This is where the Spiderbeam insulators come in. They are perfect for
the job! I have used 200 pd monofilament fishing line. You can purchase a 100M
roll for under $20.
So, now I have the 1MM reflector and driven element
cut and ready to mount.
Go to the local bike shop and get yourself an old
inner tube. they cost nothing! This is needed to place around the spreader. The
wire runs between the rubber and the spreader and is held in place by a
stainless steel hose clamp.
It was an overcast, wet and windy day today. I have
the Hex sitting on the base of my Hustler vertical. In the back ground you can
see the rotator ut will sit on.
That's tomorrows project once tuning has
been completed.
Initial testing is promising...but I cant wait for it to be
tuned!
