[TowerTalk] CM Choke

[Máximo EA1DDO_HK1H]

What happened to me at the beginning was my mistake (and lack of knowledge) regarding the units to take into account.

I am using a VNA Master from Anritsu (MS2024A) and it can't show Z, R or X, neither capacitance, Rp, etc.

So what I do is to export the data (Touchstone s2p format) including Freq, Mag and Phase. Then I import it to Excel and I do all the calculations there.

As far as I know, with Mag and Phase you can get the rest of the measures you need. It is all maths, as you can see in next link;

(At the bottom you can download the Excel files).


http://www.ea1ddo.es/medir_balun.php


My mistake was to use Mag instead of LogMag in dB.


Using three #43 cores I can reach 10K, but over a small bandwidth, during testing time.


73, Maximo

________________________________
De: TowerTalk <towertalk-bounces at contesting.com> en nombre de Jeff <keepwalking188 at ac0c.com>
Enviado: miércoles, 11 de octubre de 2017 22:17
Para: jim at audiosystemsgroup.com; towertalk at contesting.com
Asunto: Re: [TowerTalk] CM Choke

I would be interested in the specific N2PK use method for measuring
transmission chokes as well.  I never have got my Z data to come anywhere
close to what Jim has published.  By not anywhere close, I mean Z in the
hundreds to 1K range only where Jim's getting 5x that.

I know the value of the Z as it gets further from the 50R cal gets
progressively worse but I would at least like to be roughly in the ballpark,
at least where the peak z frequency is.  I don't care much about the Z value
as I generally know it's "enough for most purposes" - but what I would like
to be able to do is adjust the choke on the bench to center the peak
attenuation over my frequency of interest.

73/jeff/ac0c
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-----Original Message-----
From: Jim Brown
Sent: Wednesday, October 11, 2017 1:04 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] CM Choke

On 10/11/2017 6:46 AM, Wes Stewart wrote:
> With a decent vector network analyzer, the ports are already well-known
> (50 Ohm) terminations.  If the round robin you mention was in the July
> 2007 time frame then I was a party and measured the device using both my
> N2PK VNA and a Boonton RX meter.  I have pictures of the setups, but alas
> can't find the data.  I got some feedback that you said of my
> measurements, that they were "dead nuts on." :-)

Hi Wes,

Yes, that's the round robin I was referring to. Although my memory of it
was that the Boonton data was spot on, while other data was not. But
since you did it, I'll trust your memory over mine. :)

If your VNA data did closely match the Boonton data, we should talk off
list about your setup of the N2PK VNA, which is well known to be a fine
unit.  I certainly would like a method I can trust that is a lot less
work than the voltage divider method.

73, Jim
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