[TowerTalk] current balun question

[Máximo EA1DDO_HK1H]

Hi Jim,


I think I've got it.


If I3=0, I1 & I2 are always same value.

Any imbalance is always when I3 different than 0.


I really appreciated your help on that.


Thank you very much


73, Maximo


________________________________
De: TowerTalk <towertalk-bounces at contesting.com> en nombre de Jim Brown <jim at audiosystemsgroup.com>
Enviado: lunes, 20 de marzo de 2017 16:41
Para: towertalk at contesting.com
Asunto: Re: [TowerTalk] current balun question

On Mon,3/20/2017 5:57 AM, M¨¢ximo EA1DDO_HK1H wrote:
> Is the choke balancing I1 and I2 ?

Like Jim Lux said, the choke FORCES balance AT THE POINT WHERE IT IS
APPLIED by removing the only other path for current, common mode current
on the transmission line. So a choke applied AT THE FEEDPOINT forces I1
to be equal to I2.

> And the currents from antenna to ground? Does them count?

You need to study how antennas and transmission lines work. That's
beyond the scope of an email reflector. :)

Current and voltage both vary along the length of both antennas and
transmission lines. The ends of an antenna are an open circuit, but with
capacitances as shown in that drawing. If there were zero capacitance,
the current would be zero at the ends and the voltage would be infinite,
but thanks to the capacitance, current is very small and voltage is very
high.

The method shown in the drawing for feeding a vertical dipole is not the
only one. See this one

http://k9yc.com/VerticalDipole.pdf
End-Feeding a Center-Fed Vertical Dipole Jim Brown K9YC ...<http://k9yc.com/VerticalDipole.pdf>
k9yc.com
An End-Center-Fed Vertical Dipole Behaves like a center-fed vertical dipole ¨C ZO ~ 70 ohms, so 75 ohm coax is the best match Top half is ¦Ë/4 wire



and this implementation for Field Day.

http://k9yc.com/80M-FDVertical.pdf
Design, Analysis, Construction, and Testing of a Portable ...<http://k9yc.com/80M-FDVertical.pdf>
k9yc.com
Design, Analysis, Construction, and Testing of a Portable Antenna for 80M Jim Brown K9YC k9yc at arrl.net Glen Brown W6GJB 210glen at gmail.com



On Mon,3/20/2017 3:51 AM, Guy Olinger wrote:
> Go buy something MADE FOR the application and frequency. Then string
> it up and go have fun.

You otta be ashamed, Guy. :)  Go BUILD something designed for the
application and the frequency using my Choke Cookbook. k9yc.com/RFI-Ham.pdf

73, Jim K9YC

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