Jim inquired:
<big snip>
> >Have any of you had success with a combo 160/80 m shunt fed tower?
> >Any guess where the 80 m jumper would be with 18 inch spacing?
> >
and George replied:
> I have used my 78ft tower for years as a 160M shunt fed vertical. It has
> plenty of top loading - 5 el 20M KLM yagi and a Mosley 2 el 40. Works great
> on top band.
>
> I decided to try it for 80 and put another gamma rod on the side opposite
> the 160 M gamma. Using an omega match shorter than the other, I was able to
> easily match it to 1:1 SWR but it just didn't play. We concluded that it
> was substantial taller than a quarter wave on 80 and probably approached a
> half wave. I finally tied the two gammas together for 160 to increase the
> bandwidth.
>
> Suspect u have the same "too tall problem" as we calculated with the top
> loading u and I have on the towers, u'd need only abt 30 ft of tower to
> reach an electrical quarter wave on 80 M. Make sense??
>
It makes perfect sense to me. Been there, done that. I wonder if this
would be a good opportunity to play with some kind of decoupling stub
arrangement. Anyone out there have any practical advice along these
lines?
73,
Ken
--
___________________________________________________________
Kenneth D. Grimm K4XL
grimm@alison.sbc.edu
___________________________________________________________
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