Jim, I´ve seen someone else making a S11 measurement for CM choke?
Is that correct?
http://www.lb3hc.net/archives/1358
I always use S21.
Thank you
73, Maximo
________________________________
De: TowerTalk <towertalk-bounces@contesting.com> en nombre de Jim Brown
<jim@audiosystemsgroup.com>
Enviado: martes, 10 de octubre de 2017 15:58
Para: towertalk@contesting.com
Asunto: Re: [TowerTalk] CM Choke
On 10/10/2017 7:59 AM, Dave Hachadorian wrote:
> Speaking of "tuning" a choke, couldn't you just run 50 watts into a
> dummy load, and tee off a choke and a 100 ohm resistor to ground, and
> calculate the impedance of the choke by measuring the RF voltage
> across the resistor and the RF voltage across the dummy load?
No, because that's not the common mode circuit. There IS, however, a
method somewhat similar to that which I used for the data I gathered.
It's detailed in this set of slides.
http://k9yc.com/CoaxChokesPPT.pdf
Jim Brown K9YC Santa Cruz, CA http://k9yc<http://k9yc.com/CoaxChokesPPT.pdf>
k9yc.com
Coaxial Transmitting Chokes Jim Brown K9YC Santa Cruz, CA http://k9yc.com
FWIW, I have never gotten good data using any form of reflection-based
measurement system. The problem is that the Z of the choke is much, much
greater than the Z of the measurement system. The error shows up in the
resonant frequency.
73, Jim K9YC
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