I'm looking at a tower that is 137 ft. high and 12
inches on a face. Alowing for shortening due to the
length diameter ratio, ths is an electrical 102
degrees on 160. The series capacitane required yo
effectively resonate the tower will be somewhere
between 900 and 2500 pfd. dependent on frequency.
The radiation resistance of the tower with a good
radial system should be somewhere between 47 snd 56
ohms when tuned giving an almost flat responce across
the band. A monimatch located just before the
Capacitor with the appropriate motor driver circuitry
will automatically adjust the capacitor for the best
match. My design is for a single tower but should
also work for a four square with the appropriate
phasing box. I am also concidering raising the tower
base and using elevated radials as an option. I
thought of using a similar set up for 80 Meters only
making the tower height Five Eighth Wavelength instead.
Ted VE6AMR
------- Original Message -------
>From : Bry Carling[mailto:af4k@hotmail.com]
Sent : 3/24/2015 2:40:19 PM
To : tedc@nucleus.com
Cc : jim@audiosystemsgroup.com;
towertalk@contesting.com
Subject : RE: Re: [TowerTalk] A Capacitively Fed 102
Degree Vertical for 160Meters
I once had a shunt fed 60 foot tower that was super
effective for transmitting on 160m, even with little
or no radials... Used a variable capacitor in a box
for the "gamma rod."
Best regards - Brian Carling
AF4K Crystals Co.
117 Sterling Pine St.
Sanford, FL 32773
Tel: +USA 321-262-5471
Best regards - Brian Carling
AF4K Crystals Co.
117 Sterling Pine St.
Sanford, FL 32773
Tel: +USA 321-262-5471
> On Mar 24, 2015, at 2:25 PM, "tedc@nucleus.com"
<tedc@nucleus.com> wrote:
>
>
> Jim,
>
> Looking at the spacing on the 500 pfd. cap in the
> SA2550 it should be plenty robust for most current
> fed systems; however the breakdown voltage may not be
> high enough for a voltage fed high Z system. My 102
> degree system is current fed and I plsn to use
> variables rated at 5 to 6 Kv. in any case.
>
> Ted VE6AMR
>
>
> ------- Original Message -------
> From : Jim Brown[ mailto:jim@audiosystemsgroup.com ]
> Sent : 3/24/2015 12:09:24 PM
> To : towertalk@contesting.com
> Cc :
> Subject : RE: Re: [TowerTalk] A Capacitively Fed 102
> Degree Vertical for 160Meters
>
>> On Mon,3/23/2015 8:03 PM, Doug Smith wrote:
>> I use an inverted L for 160 with an old Heathkit
> SA2550 at the base of the
>> vertical element. The 2550 is an electrically
> driven large variable
>> capacitor, remotely tuned/turned from the shack.
>
> I had one of those in my shack for a while -- it came
> from the estate of
> a silent key, and I was helping his XYL sell his
> stuff. It looked quite
> robust, so I thought I'd like it. Turned out that it
> started arcing with
> high power on antenna that my Ten Tec 238 had no
> problems with, so I
> sold it for her rather than buying it myself.
>
> 73, Jim K9YC
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