Nobody at Force 12 wants to answer my questions, so I'm hoping someone
on this reflector might know the answer to these questions regarding the
340N/620N antenna. I picked one up used, which originally had the
shorter linear loaded elements (EF140) but now has the 53-58 footers (N
series), which seem to be a reasonable design.
First question is, what should I tune the individual elements to? For
the original elements, reflector=6780 driven=7140 and director=7460. Is
this still correct for the new longer elements?
Second question. This particular adaptation has the driven element
being mounted on the mast above the boom. I think Tom calls this the
"zagi" configuration. I have been told that by mounting the driven up
above the boom, it raises the effective height of the antenna. I'm not
too concerned with the effective height, since the boom is already going
to be at 120 feet. I thought I would mount the driven just a few feet
above the boom for convenience sake, eventhough I could mount it as high
as 8 feet above the boom. Does changing the height of the driven has
any significant effect on the antenna pattern?
Third question. The manual shows the arrangement of the old style
(shorter element) linear loading studs to be mirror images of each
other, when viewing them from above. However, the manual I have for the
new element design shows the new elements are NOT mirror images. The
way they are depicted, if you took one side of the element and rotated
it around 180 degrees in the plane of the linear loading wires so that
it is now on top of the other side, the linear loading studs would
exactly align with each other. This is counter-intuitive to me and I
would like to confirm that this is truly the way they should be
arranged.
Thanks in advance for any advice.
73
Randy K0EU
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