[OKDXA] Most Rugged Tribander

[Kim Elmore]

The student ham radio club at OU (I'm the Faculty Advisor) had a StepIR 
on top of the National Weather Center (about 190ft) and we learned that 
the wind up there is murderous I don't recommend that antenna if it's 
not easily accessible. We suspect that turbulent eddies about the size 
of the antenna itself are shed off the top of the building. This means 
that the antenna is constantly buffeted and torqued equally in all three 
dimensions, very unlike a typical installation. That makes it a 
worst-case environment up there.

We replaced it with a DX Engineering 3x10. The antenna is very stout, 
but we believe an installation error led to a mast-mount failure and it 
came down. Because of this incident, DX Engineering has an altered the 
mast mount design and will provide the new design (at extra cost) to 
anyone that asks. It is much, MUCH stronger and harder to screw up the 
mounting. The elements are also assembled with pop-rivets and so don't 
depend on any kind of compression clamps. Upon inspection, the downed 
antenna joints were still excellent. You will have strong hands by the 
time the antenna is assembled if you use a hand pop-rivet tool. The 
pop-rivet joints also make assembly errors nearly impossible.

The upcoming Bouvet DXpedition is using InnovAntennas. I have no 
experience with them, but I checked them out on their website and they 
seem very stout. Both the DX Engineering and InnovAntenna have 
intentionally tapered elements, minimizing vibration due to vortex 
shedding. Neither uses traps. During an ice storm, I witnessed the DX 
Engineering antenna in a low-frequency, high-amplitude oscillation mode 
that could have ultimately led to the mounting failure or otherwise 
possibly destroyed it; I turned the antenna 90 degrees and the 
oscillation vanished.

With all of this, if you can pick up the Jeff's TH11 cheaper than any of 
the others and choose it, make sure you use blue LocTite on every 
fastener, including the mast clamps. Then, enjoy!

73,

Kim N5OP

On 3/6/2022 2:34 PM, John Geiger wrote:
> Of the commercially available triband yagis, what is generally considered
> to be the most sturdy and rugged model?  One that can take wind and ice the
> best?  3 or 4 elements would be the desired size-something you can put up
> and not have to worry about much once it is up.  Traps would be ok also as
> I am not an anti-trap person.  Less wind loading would be a bigger
> advantage.
>
> 73 John AF5CC
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-- 
Kim Elmore, Ph

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, UAS, N5OP, 2nd Class Radiotelegraph, GROL)

/“I occasionally play works by contemporary composers and for two 
reasons. First to discourage the composer from writing any more and 
secondly to remind myself how much I appreciate Beethoven." – Jascha 
Heifetz/