[TowerTalk] 40m 4el KLM - replacing linear loading with coils

[Tom Hellem]

Hello Simon-
K7QA and I have been playing with the exact thing you are contemplating,
except that we are
doing it on an old Hy-Gain DIS-72 linear loaded 40 meter beam. We started
by winding loading
coils of 3/16" diameter copper tubing 3" i.d. 15 turns, 5-1/2" long. We
measured (and calculated)
the inductance and plugged the values into an EZNEC model and arrived at
physical lengths of the
reflector and DE of approx 290" and 274", based upon the original Hy-Gain
element taper schedule.

I am not familiar with the KLM but I am sure a similar procedure could be
done.
Also, I would be interested in knowing your proposed method of
manufacturing
the loading coils. It might turn out to be better than the one we used!

By the way we would be happy to share the EZNEC model with you if you have
the
ability to put it to use.

73

Tom
K0SN


On Mon, Apr 27, 2020 at 11:39 AM Simon Ravnič <simon at hamradio.si> wrote:

>
> Hi!
>
> After 41 years of being on the tower it is time to upgrade the antenna.
> Has anyone made a modification of 40m 4el KLM - “Big sticker” and replaced
> linear loading rods with high Q coils?
>
> We are aware of M2 offer forf coil replacement kit, but it is a bit
> expensive so we would like to do it on our own.
>
> 73
> Simon, S53ZO
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