Topband: 160m Vertical

[Dave Cuthbert]

Aloha Ron.

EZNEC ROHN25 model:

128' resonant at 1.796 MHz, 35 +j0 ohms
115' resonant at 2.000 MHz, 35 +j0 ohms

115', 1.800 MHz, 25 -j46 ohms
115' 1.800 MHz, 4.1 uH base series inductor, 25 +j0 ohms

    Dave KH6AQ

On Fri, May 15, 2020 at 6:11 AM Ron WV4P <wv4ptn at gmail.com> wrote:

> Wow,
> Incredible responses in just a few min. Thanks !
> This antenna will be used 90% for Contesting, but 5 days a week it will be
> for casual DX on CW and SSB.
> With the switching matrix I'm using at the shack, it would be hard to use a
> tuner, and is what I'm trying to avoid.
> On my JK 801's the Motorized inductor, controlled by a Green Heron
> Controller using band data from N1MM makes it totally automatic (Flat SWR
> in ~ 50khz segments)
>
> From my talk with Mike @ Tornado Tuner, the 160m version, that I believe
> was made for a short radiator is as follows...
>
> *"The Tornado 160SS will tune from about 17uH to 33uH. It has a single 27.5
> turn coil.  The coil is 1/4” diameter aluminum, and the coil is 4 3/8” mean
> diameter."*
>
> From the replies, I see that my approach of build it and figure out the
> tuning later was the wrong misguided.
> Please forgive my ignorance, I don't have the experience or background to
> understand what a lot of this means. It seems that IF I wanted to use the
> tornado tuner, I would need to figure out a way to model the antenna so
> that adding 17uH to 33uHof inductance would allow it to tune across or
> close to across the band ? And that them numbers may be way out because it
> was designed for s shorter element ?
> I want it Automated so I can put any poor soul I can convince to join a
> multi op in the seat and just turn them loose.
> Thanks again for all the great replies so far, *and Frank... Loved the
> presentation of the LPL history yesterday, Incredible. *
>
> Ron, WV4P
>
> *Grant, Going to read your Doc now, If it sends, I have attached a pic of
> the base I built. The other next to is is one of 3 I made for the 3
> Rotating Towers I am putting up. *
>
> On Fri, 15 May 2020 at 10:34, Tree <tree at kkn.net> wrote:
>
> > One approach for the inductor that I have used when doing parasitic
> element
> > tuning is to put two SO239's in series and either put a shorted plug in
> for
> > no added inductance - or a PL259 fashioned with a few turns of heavy
> gauge
> > wire.  You can label them for the frequency you are wanting.
> >
> > I used that technique to go from a director to a reflector back when I
> was
> > playing with a vertical parasitic array on 160.
> >
> > Tree N6TR
> >
> > On Fri, May 15, 2020 at 8:28 AM <donovanf at starpower.net> wrote:
> >
> > >
> > > Hi Ron,
> > >
> > >
> > >
> > > A more reliable approach is a tuner in your shack. The extra coax
> > > cable loss from elevated VSWR is insignificant on topband.
> > >
> > >
> > > How high up the band do you want to go and at what maximum VSWR?
> > >
> > >
> > > A resonant Rohn 25 160M vertical will be about 124 feet tall for
> > > resonance around 1820 kHz
> > >
> > > If for some reason you must install a tuner at the feed point of the
> > > vertical, follow Tree's advice and make it slightly short: 120 feet
> > > of 115 ft if you need to tune for minimum VSWR above 1900 kHz.
> > >
> > >
> > >
> > > Use a small tapped inductor to tune it around the band.
> > >
> > >
> > > 73
> > > Frank
> > > W3LPL
> > >
> > >
> > >
> > >
> > >
> > > ----- Original Message -----
> > >
> > > From: "Tree" <tree at kkn.net>
> > > To: "Ron WV4P" <wv4ptn at gmail.com>
> > > Cc: "160" <topband at contesting.com>
> > > Sent: Friday, May 15, 2020 3:18:39 PM
> > > Subject: Re: Topband: 160m Vertical
> > >
> > > Slightly shorter makes it easy to use an inductor to make up the
> > > difference. If you make it long - you can do the same with a capacitor
> -
> > > but it's typically more trouble than the inductor.
> > >
> > > Tree N6TR
> > >
> > > On Fri, May 15, 2020 at 8:15 AM Ron WV4P <wv4ptn at gmail.com> wrote:
> > >
> > > > I have built an insulated base for a 1/4 wave 160 antenna. The
> antenna
> > > > will be XXX' of Rohn 25. In searching I see people using heights from
> > > 115'
> > > > - 130' with a pretty high number around 124'.
> > > > I do not know how I am going to match it yet, I figure I will do my
> > > > research on that once it's up so I can learn while experimenting....
> > But
> > > > the height has me second guessing. I want it tunable across the band,
> > > > perhaps using a Tornado Tuner like my JK 801's have with a motorized
> > > > inductor ? But the question at hand is do I want the antenna Tall or
> > > Short
> > > > ? What is the Method behind the Madness ? :o)
> > > >
> > > > Thanks in advance,
> > > > Ron WV4P
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