Speaking of broadbandedness.
OK, what differences would it be bandwidth wise?
Where does it matter to get the wider bandwidth/
At the feedpoint?
At the far end?
In other words, you get broader bandwidth using Rohn 25 than using say a
4" irrigation pipe.
Now how about if you have a broad base like a self supporting tower
where the base is like 6 feet apart legs and then it tapers down to only
a foot at the top. Would that be broader than the Rohn 25?
Or take it the other way, take that same tower but put it up-side-down..
It is 12" across at the base at the feedpoint, but it is 6 feet wide at
the top.
what would the bandwidth be like with that?
Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 5/15/2020 10:52 AM, Ken Claerbout wrote:
I would favor using an inductor. Tune it for the lowest part of the
band. Then using a relay or two, you can short out turns if you want
to move higher in the band. Although I think you will find using Rohn
25, it will be pretty broad.
73
Ken K4ZW
On Fri, May 15, 2020 at 11:28 AM <donovanf@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@kkn.net>
To: "Ron WV4P" <wv4ptn@gmail.com>
Cc: "160" <topband@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@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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