[ADXA] Get 160m inv L to 80m?

[Dennis Schaefer]

Using a trap seems like an good option.  Traps made of coaxial cable
generally work  well even though the Q isn’t as high as traps with discrete
L and C components.  I’ve made and used them in dipoles, but not in a
vertical.

There is an antenna called the Battle Creek Special that was loaned out to
several DXPeditions.   I think it covered 160, 80, and 40 using coax
traps.  It was generally set up as an inverted -L.

I’ve made fan dipoles from ladder line and they work fine even though many
would say spacing must be 6 inches or some other arbitrary figure.    I’ve
thought about making an inverted-L using <>65 feet of ladder line and
adding a wire to one side to resonate on 160.   Connect the two ladder line
conductors together at the feedpoint.  It would be like half a fan dipole.
  It might  take several adjustments to get it right on both bands, and if
using a tree, that could be tedious.   You could also just use a second
wire  as the 80M radiator.

My 160M inverted-L has ONE radial.  It definitely needs a few more.

73,
Dennis/RZ

On Thu, Feb 20, 2025 at 10:37 AM Jussi Eloranta <eloranta at aa6kj.hopto.org>
wrote:

> Hi,
>
> I have inv L (with about 80 radials) for 160m (quarter wave length). I am
> wondering if there would be some good way to get it to resonate also on
> 80m? Of course one solution would be to install a relay that would make the
> radiator longer/shorter but a bit tricky to do in practice. Any thoughts?
>
> Jussi (aa6kj)
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