G'day all,
Its been a while since I've posted, but I decided to:
1/ Move my antenna system from the backyard to the front yard. The reason being, with all the tall palms/ bamboo and then all the sheds we have, this is all going to effect the antenna. Whereas is the front yard, it had a clear view to the ocean with no obstructions.
2/ Design a whole new antenna. In other words, get back to basics. (verticals/ dipoles or random wire)
3/ Get up to speed using my new paddle (never used one before)
Being that I already had a 10m squid pole, I looked around the net looking at various types of verticals, one of which was the DX commander. After a bit of research, I doing a bit of number crunching, I decided to model a 3 element version in EZNEC (antenna modeling program) to see how the elements interact with each other (if at all) and also to see what the RF patterns would be like compared to a typical 1/4 wavelength vertical. After a bit of pushing and pulling the antenna, I was finally happy with the output. I then I modeled the antenna in AutoCAD, designing the parts to print out and then construction began.
First thing was the spreader plates which I made from some chopping board (HDPE) material from the
$2 store.
Next was the ground and element plate. I had an old 3mm aluminium BBQ cover plate tucked away in the corner of the shed, so I grabbed this. Bit scruffy, but after making it I polished it to bring it back to new.
I then dry fitted it all together
In the picture below, you can see on the table another ground plate. This plate I discarded because when I was bending the tongue, it was a bit to close to the element plate. Easier to make another one
My wire arrived from Jarcar, so time to duck down to the hardware store for some SS nuts & bolts, electrical forks, SS clamps and hose and some PVC pipe. Time to put it together
Here I took out the insert of the base cap and found that 40mm PVC pipe fitted perfectly inside the lower tube. So I cut a section of pipe 300mm or 1 ft long and inserted it
Next I had some 50mm PVC pipe, so I bought a cap to fit, marked the centre of the cap and then drilled and dremeled out a 40mm hole. I cut the pipe so that it was 300mm long, ground a chamfer on one end and pushed this into the dirt where I wanted the antenna to be.
Time to stand the antenna up for a dry run. Here you can see the antenna cap is now sitting on the PVC cap and with the 40mm pipe inserted into the pole itself and also the 50mm, this antenna base is rock solid and going nowhere
Initially I only used the lower guys to steady the pole and I knew I would be dropping it down again and again with tuning the elements.
End SWR result:
40m = 1:1
20m = 1.3:1
15m = 1:1
10m = 1:1
I'll just use the ATU to bring 20m down to 1:1
Radials... 9 bundles (4 radials per bundle) = 36 radials in total. Each radial is 10ft-7" ( 3.22m) long
Then it was time to drop it down again, install the upper guy lines and stand it back up. Rock solid in 25 kts winds. Just have to wait for my shock cord to arrive then its finished.
Total cost to build?
$112
So overall I was pretty happy with it. Later that day I cranked up 20m and made contact with Mark (VK3MJ) 1377 miles away on 5 watts (579 report) and a day later on 1/2 watt. Trying the rest of the bands on 5 watts I watched the RBN to see if I was getting spotted and saw that the USA/ Canada/ Europe and others were getting my signal.
All in all.. very happy with the result.
Catch you on the bands !
