My G3ZY based multiband HF Dipole

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My G3ZY based multiband HF Dipole Empty My G3ZY based multiband HF Dipole

Post  G7VGG on Thu Jun 11, 2009 5:13 pm

I wanted to make my 80m doublet more efficient on the upper HF bands because it became less and less efficient the higher in frequency I went, so I decided to "multiband" it.
I found a multiband dipole design by Jack Tweedy (G3ZY) in the September 1994 edition of Practical Wireless magazine and I was very impressed by its increadible simplicity and the fact that it only required a small amount of wire compared to other multiband HF antennas. This also made it much lighter in weight than other multiband HF antennas and it reduced windage to a minimum. The lack of traps also makes it far more efficient than trap dipoles.
I changed the original G3ZY design a little by covering all bands from 80m up to 4m and by designing my own inverted T shaped combined spacer/spreaders, which I made from 60mmx60mm square UVPC guttering downpipe, cut out with a bandsaw. These clip onto the top 80m element and allow each resonant band element to be kept seperate from each other whilst holding the feed wire that joins each element in turn to the 80 m element...As you can see in the photos below. In the first photo the feedpoint is off to the right and in the second photo its off to the left:

My G3ZY based multiband HF Dipole Dipoletpeicefront1

My G3ZY based multiband HF Dipole Dipoletpeiceback1

And here is a pic showing the general arrangement of the elements...The 4m element is the bottom one coming out of the feeder and then the order goes 6m, 10m, 12m, 15m, 17m, 20, 30m, and 40m...The top wire is the 80m element.

My G3ZY based multiband HF Dipole Dipolehanging1b

Unfortunately I cannot cover top band as yet so that will have to be worked on at a later date.

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Join date : 2009-05-04
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