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Re: [TowerTalk] CM Choke

To: <jim@audiosystemsgroup.com>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] CM Choke
From: "Jeff" <keepwalking188@ac0c.com>
Date: Wed, 11 Oct 2017 17:17:22 -0500
List-post: <mailto:towertalk@contesting.com>
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
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- From: Jim Brown
Sent: Wednesday, October 11, 2017 1:04 PM
To: towertalk@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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