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

[Richard (Rick) Karlquist]

On 4/27/2020 10:38 AM, Simon Ravnič wrote:
> 
> 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

The problem is that you don't know the required inductance
of the coils.  It would be difficult to determine this
for anyone but M2.  At one time, W6ANR used to sell
coils for 40 meter Yagis.  Perhaps he has the values
and would be willing to give them to you.

The recent TT thread about determining the resonant frequency
of Yagi elements would help you.  You could find the 4
resonant frequencies of the 4 elements of the unmodified
Yagi, and then use trial and error to tune the inductors
to get the same element frequencies.  Seems like a lot
of work.

Rick N6RK