The top hat tubes sound pretty unwieldy to me. You're going to need to
guy the vertical section in a couple of different places anyway, so why
not just make the top set of guys partially out of large diameter
aluminum wire? I built a similar antenna several years ago, and 48 feet
of 2 inch diameter tubing required four 1/8 inch diameter wires each
about 11 feet long to resonate on 80m. I modeled it ahead of time with
EZNEC and it required almost no trimming when I built it. The aluminum
wires were each wrapped once around the tubing and fastened with a
sheet metal screw, then angled out at about 45 degrees if I remember
correctly. Each of course had insulated line for the rest of the length
to their anchor points. I don't guarantee that these dimensions will
work exactly for you, but they should be close. The diameter of the
tubing and the top hat wires both make a difference.
73,
Dave AB7E
W5CPT wrote:
> Here is what I plan to do for an 80M vertical. Please feel free to advise
> what else I might do or to warn me what not to do.
>
>
>
> I am going to Dallas TX in June for HamCom and while there I plan to visit
> Texas Towers and purchase enough aluminum to build an 80M vertical. I plan
> on getting 4 each 12 foot pieces of tubing starting at 2" for the main
> radiator. I also plan on getting 3 each 12 foot pieces of 3/8ths tubing for
> the top hat. This will give me a 46.5' tall radiator with a six part 6 foot
> each top hat. My plan is to cross drill the top section which will be 1.625"
> and space the three sets of spokes about an inch apart as close to the top as
> I can drill. I will use hose clamps to keep them in place. The base will be a
> set of insulated clamps from DXEngineering to a plate attached to a 4X4 sunk
> in the ground.
>
>
>
> I then plan to erect it over about a mile of ground mounted radials evenly
> distributed in a circle in my yard (I love living out in the country) and
> sticking my MFJ-259 on the feed to determine the amount of matching I will
> need. I assume I will need some inline L to bring it to resonance. I
> realize it will probably not cover the whole band but I will tune it for the
> center and let the tuner in my radio widen the usable bandwidth.
>
>
>
> Your comments please.
>
>
> Clint - W5CPT
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