----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
To: <topband@contesting.com>
Sent: Thursday, July 12, 2012 11:58 PM
Subject: Re: Topband: Mother of all ferrite common-mode coaxial chokes
> On 7/12/2012 5:48 PM, ZR wrote:
>> Considering the YCCC's long time reputation for top level engineering
>> ability plus the others mentioned such as K3LR Id consider that article a
>> must read.
>
> The 2006 W1HIS piece gets many things very right but some things very
> wrong. Tom has noted some things that are wrong.
** Which is strictly his opinion.
Another is that Chuck
> didn't understand the chokes he was recommending and trying to measure,
> and he didn't know how to accurately measure them.
** Since when is using an established procedure called not knowing how to
measure?
He also didn't know
> about the relatively new #31 material.
** Thats strange since he mentions the large 31 Mix beads a few times
including their 3/2005 purchase date.
He wasn't alone in any of that.
> I got good measurements by measuring the chokes as the series element of
> a voltage divider. Some guys working with the German VNWA have
> implemented this in the software that supports it. Some guys working
> with the N2PK VNA read the Agilient work on the IV method, and developed
> a test fixture to implement it. All three of these methods can get good
> data.
>
> I had been working on ferrite research for three years by the time I saw
> Chuck's peice, and I corresponded with him about it. One MAJOR point he
> got right is the importance of killing RX noise by killing common mode
> current on the feedline, and it was one I hadn't thought of. I haven't
> seen anything that Chuck published after this (six years ago), but I
> consider my work much more advanced than his.
** Killing common mode for RX goes back long before 2006.
I keep referring to the Tempest program and other screen room testing that
goes back into the 70's and early 80's. Apparently you and Tom reinvented it
decades later but since I was Tempest cleared/certified I and many others
had been using it all along and there were no secrets about it
either....just no Internet for instant distribution of knowledge.
>
> Some top level engineering does, in fact, occur outside New England.
> Like in Georgia, and on the west coast. :)
** I agree, CA has a high percentage of the brain power in the US and GA has
Georgia Tech and the companies that sprung up in the area by their
engineering degreed graduates. There are 14 engineering schools in the state
making GA well represented in various Engineering DEGREE programs.
Carl
KM1H
>
> 73, Jim K9YC
>
> .
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
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