[TowerTalk] Worse than MFJ/Cushcraft coils

[Michael Tope]

Dave,

Using aluminum wire is not necessarily bad trade for antenna loading 
coils. Its lighter, so you can make the wire diameter larger for the 
same weight to compensate for the lower conductivity. AFAIK, Cushcraft 
uses aluminum wire in all their traps. Another interesting example is 
the KLM linear loaded Yagis. The linear loading stubs that provide the 
inductive reactance needed to shorten the elements are made from 
aluminum. Electrically, the old KLM 40 meter 4 element Yagi is good 
performer.

The Create 3 element 40 meter antenna you mention may be a poor 
performer because the designer didn't account for the extra losses of 
the aluminum wire when doing the design. If there is a lot of loading 
required (elements are very short physically) and the wire diameter is 
too small, then I^2*R losses in the inductors will be excessive even 
with copper (and all the worse with aluminum). However, that Create 
antenna may not play well for other reasons (there is more than one way 
to screw-up a Yagi). Wilson built a 3 element full sized 40 meter Yagi 
back in the '70s that didn't perform very well if you used the 
out-of-the-box dimensions. This is because the design dimensions didn't 
compensate for the steep element taper. If the element lengths were 
adjusted to take that into account, I understand the antenna worked very 
well.

73, Mike W4EF.............

On 9/15/2019 9:34 AM, Dave Thompson wrote:
> Gang,
>
> I had a 3 el Create 40 meter beam on a 36 foot boom sold by a California firm but the beam was made in Japan.  The coils were wound with aluminum wire.  The beam sat on top of the ower until I decided my lower wire antenna worked as well.  I bought the 2 el Cushcraft 40 and never looked back.  Several locals bought Create Tri-Baners and they seemed to work well. I asked one KB4J and he never looked into the coils and he sold the beam when he moved to South GA at retirement.
>
> Stay away from the original Create beams made in Japan.
>
> 73 Dave  K4JRB
>
> -
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