[TowerTalk] Worse than MFJ/Cushcraft coils

[Glenn Pritchard]

Hi Mike 
I had that Wilson 40 meter Yagi in the 70’s, well 1980 to be exact, problem was the driven element did not compensate for the extreme taper. The tuning for the gamma match and yes the reflector has to be taken into account.
You had to have the antenna installed, climb the tower and adjust the variable capacitor at the feed point. Pain in the butt, but it did work after the changes and worked very well.

Glenn, VA7UO 

Sent from my iPhone

> On Sep 15, 2019, at 2:52 PM, Michael Tope <W4EF at dellroy.com> wrote:
> 
> 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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