Not if you use enough radials. I don't think I've ever seen ferrite
cores out on heliax at AM broadcast towers. If you use enough
radials, the return current will be so divided down that the current
on the outside of the feedline (burying it helps but isn't necessary)
will be negligible.
Interesting.
Never though on that.
Perhaps, Some kind of "sleeve balun" ?
Grounding the coax's sleeve at 1/4 wl from antenna base.
Thanks.
73, Maximo
<http://foro.ea1ddo.es/>
________________________________
De: TowerTalk <towertalk-bounces@contesting.com> en nombre de Rob Atkinson
<ranchorobbo@gmail.com>
Enviado: jueves, 9 de abril de 2020 11:11
Para: towertalk <towertalk@contesting.com>
Asunto: Re: [TowerTalk] Vertical Antenna Question
You also need to invest in some 31 mix toroids or clamp ons - choking your
feedlines is going to be important.
Not if you use enough radials. I don't think I've ever seen ferrite
cores out on heliax at AM broadcast towers. If you use enough
radials, the return current will be so divided down that the current
on the outside of the feedline (burying it helps but isn't necessary)
will be negligible. If you have to use ferrite cores to keep RF off
your feedline exterior, you don't have enough radials down.
The Cushcraft R7/R8/R9 Verticals are 1/2 wave so they do not require radials.
That's only true if they are vertical dipoles. If they are 1/2 wave
monopoles, they still need a ground system regardless of the
manufacturer's snake oil sales pitch.
73
Rob
K5UJ