[TowerTalk] Another way to make a CM choke ?

Máximo EA1DDO_HK1H ea1ddo at hotmail.com
Fri Dec 15 01:49:17 EST 2017


To convert those Mag and Phase values to Complex Impedance (aka Choke Impedance) you can use next calculator (Excel spreadsheet):


http://www.puertobalsillas.com/radio/Balun_Guanella_4_1/Calculadora_Impedancia_Compleja.xlsx


(It is part of this web site: http://www.ea1ddo.es/medir_balun.php )


73, Maximo


________________________________
De: TowerTalk <towertalk-bounces at contesting.com> en nombre de David Robbins <k1ttt at verizon.net>
Enviado: jueves, 14 de diciembre de 2017 21:48
Para: towertalk at contesting.com
Asunto: Re: [TowerTalk] Another way to make a CM choke ?

Ancient reference for aircore baluns:  http://www.k1ttt.net/technote/airbalun.html


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373



-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of David Gilbert
Sent: Thursday, December 14, 2017 21:12
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Another way to make a CM choke ?


I'm pretty sure some of the common mode choke approaches do exactly that ... except using the stray capacitance between the shields of the turns to get the resonance.  I suspect there are websites showing the right configurations (number and diameter of the turns) necessary for resonance.  It's been a while since I read Jim's paper, but I think he mentions that approach as well.

Dave   AB7E



On 12/14/2017 1:32 PM, Jim Thomson wrote:
> Ok, for MONOband use only, what about a simple parallel resonant circuit, consisting of a solenoid coil of  50 ohm coax + parallel resonating fixed or variable cap, or padding a variable cap ?
> With cap wired between input and output braid.  On paper, this appears to be a  very high Z, and low Q device.  And wide enough to cover one ham band in question.   Is it doable ?
> Whats the optimum  L to C ratio  for this concept to work ?   IE; we would want the highest Z practical, but a Q such that the high Z covers an entire band, or portion of one band, or freqs of interest.
>
> Jim  VE7RF
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