Topband: 160m Vertical

[Joe]

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
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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 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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