So the impedance transformation of the feedline is important to get the right
split of power between the elements.
Yeah, don't go adding length with the choke. Or, you can fool with the
equations for the Christman feed and find the correct lengths that are longer.
One challenge, sometimes, is that the physical length of the lines is shorter
than the distance between elements. In which case you need to redesign the
feed.
(you can, I think, always add integer half wavelengths to both sides)
On Mon, 2 Dec 2024 19:14:10 -0500, Mpridesti <mpridesti@yahoo.com> wrote:
This will be an elevated 2 element phased vertical system using the Christman
design with 50 ohm feed lines.
Regards,
Mark, K1RX
> On Dec 2, 2024, at 6:18 PM, Jim Lux wrote:
>
>
>
>
>
>
> how deep is it buried? Skin depth of the soil at HF isn't zero (except for
> those folks with the array in a salt water marsh, and even there...), so the
> shield of the coax acts as a radial. Although the choke would affect that, as
> well since it chokes the current on the outside of the coax.
>
> One big advantage of feedline chokes is that they make the behavior of the
> overall system more "predictable".
>
>
> On Mon, 2 Dec 2024 14:49:44 -0500, wrote:
>
> I used a small diameter 75 ohm PTFE coax for the choke and shortened the
> feedline accordingly.
>
> I wonder of a ground mounted vertical with buried coax really needs a choke?
>
> John KK9A
>
>
>
> K1RX wrote:
>
> Building a set of phased verticals and the phasing lines are critical (of
> course) so my question here: by adding 18 inches of cable length (choke
> length) does the phasing line length need to be shortened by 18 inches?
>
> Or should I consider the choke as part of the antenna and not make any
> adjustments?
>
> Regards,
>
> Mark, K1RX
>
>
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