[TowerTalk] Measuring Common Mode Choke with Anritsu VNA

Máximo EA1DDO_HK1H ea1ddo at hotmail.com
Tue Jan 2 05:10:00 EST 2018

Hi Jim,

One more question. regarding the voltage divider (from your slides) to measure chokes.

Should I calibrate the VNA with that voltage divider connected?

Thank you very much

73, Maximo

De: TowerTalk <towertalk-bounces at contesting.com> en nombre de Jim Brown <jim at audiosystemsgroup.com>
Enviado: martes, 2 de enero de 2018 2:40
Para: towertalk at contesting.com
Asunto: Re: [TowerTalk] Measuring Common Mode Choke with Anritsu VNA

On 1/1/2018 6:10 PM, Avery Davis wrote:
> I apologize for not being more clear, but the point of the
> exercise is not to measure the complete complex impedance to within 10%,
> although you are right that a simple S11 reflection measurement has a
> limited impedance range depending on the instrument, but to  assess the
> suitability for use in a certain frequency range, and the S11
> measurement on a Smith chart will clearly demonstrate resonance effects
> and the effective frequency range.


Somehow I failed to clearly make the point that measurement errors
associated with measuring high Z chokes with S11 is NOT a relatively
small error, like 10%. It can be a VERY LARGE error, like 50-70% in
resonant frequency. Which FAILS to allow assessment of suitability for
use in a given frequency range.

73, Jim


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