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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