Ham Radio  VK3FORK

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Having recently taken an interest in amateur radio , and being a experimenter and tinkerer , I had to build my own antenna .
The simplest , cheapest and easiest to tune has to be the vertical dipole . ATM I'm very much into 2 meter and 70cm so this
is what I was aiming to cover building my dipole .

The very first thing I did was source a pole , in this case it was a 8 meter collapsible squid pole made from fiberglass . The last two
pieces were to thin and whippy so were removed , leaving me with a still flexible 6 meter pole . So the first consideration was weight ,
the antenna simply had to weigh next to nothing .  The next consideration was sourcing parts for the build , and for this I took a trip to
my local Bunning's , to see what was available for DIY antenna building . Now at first I had watched a lot of YouTube video and read
a lot of DIY antenna build guides . So having a slight idea of what direction to go in I was of to Bunning's .

1. PVC pipe , cheap dial calipers say 22mm OD , Bunning's sells it in 1 meter lengths ( you just need one length )
2. 90 degree elbow to fit
3. T connector to fit
4. 10mm aluminum tube ( Bunning's sells it in 3 meter lengths ? or 1 meter lengths / 3 meters is cheaper if memory serves )
5. I used 22mm wood dowel inside the T piece for the elements
6. You will need assorted self tapping screws

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How to build it .

I start by fitting the wood dowel inside the T piece , a good interference fit is what I strive for . When the dowel fits well I use a saw to cut it of flush
with the PVC fitting . Once I have both ends done , I then drill a 10mm hole as central and as straight as I can through the dowel for my 10mm
aluminum tube .

The tube was cut to 24inches ( 610mm )  the first time I did this , just to be on the safe side and not make the radials to short . As it turned out this was a little
on the long side . I would suggest 20inches ( 510mm ) to start . I press the tube into the dowel a few mm past the dowel face on the inside , this might be
between 15mm and 20mm leaving you with just over 19inches ( 490mm ) of radiating element .

Once the PVC T piece has the dowel and aluminum tube fitted , I drill a small hole through the PVC - Dowel and aluminum tube , and
screw in a self tapping screw long enough to go through both sides of the aluminum tube . The screws serve two purposes , they hold
everything together as well as allowing us to connect the coax .

That's it , that's the hard part done . All we do now is fit a short length of PVC pipe to give us a arm to hold out the antenna , we fit the 90deg
elbow and another length of PVC pipe , which can be mounted to a pole , and in my case its almost perfect as it slips over the squid pole
and becomes a interference fit , holding it firmly in place with no need for further hardware .

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Tuning the Dipole

You will need a SWR meter for this part .

I start by checking SWR @ 144.050mhz ( low ) and 147.950mhz ( high ) to see what I get .
Apparently the rule for tuning is :

High SWR on high freq = Antenna is to long
High SWR on low freq = Antenna is to short

Using a pipe cutter , I trim both elements ( 1/4inch at a time ) until I get close to equal SWR or the lower frequency is almost 1 to 1 .
Its important to clean the ends of the antenna where you are trimming as rough ends can affect the SWR reading .
With this antenna I was 1.04 ( low ) and 1.34 ( high ) when I decided to clean ( de-bur ) the ends . After re checking
the SWR it was 1.03 to 1 to 1.04 to 1 across the 2 meter band .
( 17 1/4 inches or 438mm )
On 70cm ( 430mhz to 450mhz ) its about 1.8? to 1
And I'm using 10 meters of RG58U to connect the antenna to my radios , as well I have used RG174 with good results .
( Maximum power might be 5watts of transmit power )
This is my 3rd Bunning's Dipole , and they are amazingly light weight , and can be used on 70cm .
( I call it the Bunning's dipole as the parts come from Bunning's )
If you're into hand held transmitters , then a simple dipole like this one can seriously increase your range for
both receiving and transmitting , and it simply kills any rubber ducky or small to medium whip .