Such a cable has practical no attenuation on 160 meter. You can simply do all
the tuning in the shack.
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Van: Ron WV4P
Verzonden: zaterdag 16 mei 2020 23:46
Aan: Richard (Rick) Karlquist
CC: Rob Atkinson; 160
Onderwerp: Re: Topband: 160m Vertical
Thanks again for all the replies, it kind of jumped around on my end
between on and off list replies. Hopefully I have not missed any.
The Feedline will be ~300' of 7/8 CellFlex.
Legal Limit on power.
About 8000' of Radials, In theory, 64 @ 120' but rough terrain will
necessitate some flexibility.
So far from the replies I have come up with.
- ~115' Of Rohn 25 resonate high in the band.
- An Air Core Inductor at the base with 4 taps, switched with relays to
make it usable across the band.
- A Shunt Coil for static bleed and to bring the feed-point impedance up
to ~50 ohms
Ron, WV4P
On Sat, 16 May 2020 at 12:56, Richard (Rick) Karlquist <
richard@karlquist.com> wrote:
> On 5/16/2020 4:31 AM, Rob Atkinson wrote:
> > On 5/15/2020 8:27 AM, donovanf@starpower.net wrote:
> >
> > ""A more reliable approach is a tuner in your shack. The extra coax
> > cable loss from elevated VSWR is insignificant on topband.""
> >
> >
>
> Another disadvantage of a tuner at the shack end is that the match
> bandwidth for any given setting of the tuner becomes narrower.
> I have over a full wavelength of open wire line to my 160m
> vertical. No problem with power handling, VSWR handling or loss,
> but the match bandwidth is very narrow if the OWL is badly
> mismatched. There is a 450 ohm to 50 ohm balun/transformer at
> the tower, so I only have to match the antenna to unbalanced
> 50 ohms. There is another transformer at the shack end.
>
> I should also point out that the charts showing "Additional loss
> due to SWR" were incorrect for decades in various ham publications
> and were only recently corrected, in case you hadn't heard.
>
> See:
>
> https://ac6la.com/swrloss.html
>
> Rick N6RK
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