For a 43 foot vertical antenna, to match it on 1.83 mhz, you need an 82 uH
coil at the antenna base.
If you use a 3 inch diameter coil form, and wind 20 turns per inch, you will
need 33 turns of wire on the coil to get 82 uH.
The coil is not simply the missing length of wire wound on a coil form. In
this example, the length of wire wound on the coil form is about 26 feet.
And for a quarter wave vertical antenna, the full size length is calculated
by 234/length in feet. For 1.83 mhz, this is 128 feet.
Carl Moreschi N4PY
121 Little Bell Drive
Hays, NC 28635
www.n4py.com
----- Original Message -----
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
To: <tentec@contesting.com>
Sent: Monday, August 16, 2010 3:01 AM
Subject: Re: [TenTec] swr
> You could always try a Hygain AV-6110 for $250 bucks.
>
> Grabbing my handy Lightning Calculator copyright 1932, I see my coil
> would be about 300 microhenries and the few on line references about
> such a loading coil tend to show 42 to 70 microhenries. Where my coil
> would be 6" diameter and 4" long with 12 turns to the inch, a 50
> microhenry coil would be 3" long, 2-1/2" diameter and 12 turns to the
> inch. And if it wasn't enough inductance for resonance, it would still
> definitely improve the load Z for the tuner.
>
> 73, Jerry, K0CQ
>
> On 8/15/2010 9:54 PM, Ken Brown wrote:
>>
>>> Fundamentally the 43 foot
>>> vertical is way too short for 160 and needs a BIG loading coil
>>> containing about 77 feet of wire, and forcing that to be done in the
>>> tuner will tend to smoke the tuner.
>>>
>> You are correct that a 43 foot radiator is way to short to be resonant
>> on 160 meters, and either an added length of wire or an inductance can
>> compensate for the capacitive reactance to make it a non-reactive,
>> resonant load. I do not think that you are correct to say that a
>> loading coil would require 77 feet of wire to provide the necessary
>> inductive reactance. Because of the coupling (mutual inductance) of the
>> multiple turns of the coil, the necessary inductive reactance will be
>> had with less than 77 feet of wire. If it is not wrapped into a coil,
>> then 77 feet would be about what you would need.
>>
>> DE N6KB
>>
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