... on the move again.
Well, at last everything is back to normal at this QTH, as far as the impact on ham radio over the last few months is concerned, given all the excitement surrounding the general elections, the winning 4-peat Government and subsequent swearing in ceremony for the newly elected constituency representatives on Sunday 7th February. The national political action is not over but its impact on my own local ham radio is done. So I am picking it up where I left off last year.
The 18-foot length of aluminum tubing is already mounted on the mast. You may recall earlier I was going for the option to re-install the single band 40-meter top and bottom loaded vertical dipole antenna. This is the first step towards my 2010 antenna experiments, that of phasing two top and bottom loaded vertical dipole antennas. The two masts are already about 30 plus feet apart, so that limits the number of phasing combinations and configurations. The vertical elements are only 1/8 wave tall, even though I prefer 1/4 wave long elements. But since I can get two [2] antennas instead of one [1] and I won't miss the fraction of a dB in gain, I took it.
According to Captain Paul Lee I can max the gain with 30 degree spacing and 165 degree phasing, if my memory serves me well ... but I don't know if I may need a sophisticated device like the AIM4170 to compute the parameters, or maybe the ON4UN software may still prove helpful. But if I was in the jungle without the high tech tools what would I do? So it is back to basics again until such time as. There is still so much that can be done with the knowledge and application of basic principles, simple tools, and gadgets.
I note that readers wish to get construction details and photos of the antennas built. A picture is worth 1000 words, maybe 5000 sometimes. I do not build antennas like they are going in for any beauty pageant. They are built for performance not for looks, as you will see. Given the hot Caribbean environment I do not have to take 'certain' precautions, neither do I have to meet any building code requirements or restrictions, and common sense would dictate that safety is always priority #1. So one should bear this in mind when viewing any photos of my antennas and their construction. A word of warning, if you have any uncomplimentary comments please keep them to yourself, so that mutual respect can be maintained and we all remain squeaky clean. Enough said.
A solenoid balun is critical to vertical antenna performance. If you wish to use a ready made balun on your vertical antenna that is cool, but if you are on a budget like me, you must be thrifty, reusing and recycling at every opportunity. Earlier up like 2008/2009, I made the solenoid baluns on 4.5-inch OD PVC pipe with [a] two PL-259 on ends, which required [b] one PL258 to connect the 1/2-wave-multiple tuned coax cable feed line with two PL259 on ends, [c] one M358 for balun, matching network and driven element, and [d] one SO-239 on coax braid tail from the driven element.
Yesterday I decided to reduce all this hardware down to one PL259 and two ring terminals, thus retrieving three PL259, one PL258, one M358 and one SO239. The antenna feed line is even 1/2-waves at 7.00 MHz. The balun is still made up from 20 to 30 feet of coax cable, wound on the 4.5-inch OD PVC pipe, and it needs 40 feet to connect the antenna to the rig inside. One electrical wavelength about 94 feet seems adequate for this feed line with a built in balun. This is going to be a permanent installation.
Still on the thrifty side, I did not wish to cut from a new roll of coax cable so I spliced two bastard pieces of coax, 61 feet and 38 feet. Over the last few years, various phased array experiments have resulted in a few 'arbitrary length' of coax cable which I will now splice and reuse on the permanent vertical dipole antennas installed at this QTH.
I plan to take a few snaps later when I resume work on this 40-meter top and bottom loaded vertical dipole antenna.
73
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