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Re: [RFI] Bulk order source for Ferrite beads?

To: rfi@contesting.com
Subject: Re: [RFI] Bulk order source for Ferrite beads?
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Wed, 20 Feb 2019 01:17:13 -0500
List-post: <mailto:rfi@contesting.com>
No natter how long we're in here there's always something new to learn.  Thanks for all the work Jim.

Too bad so many of the newer generations of hams have so little interest in the technical aspects, but I think that is true for all STEM subjects. Wayyyy back and the occupy Wall Street, I remember a girl being interviewed who was complaining about all the good paying jobs going to those majoring in STEM subjects (paraphrased). The interviewer then asked if she knew that, then why not major in one of those subjects.  The answer? Oh, those are too hard! They expect to find any info they need using Google.  If that doesn't work then it's too hard.

Each generation has had a label. I guess I'd call the present one, the "Look Up Generation", or the Google Generation"

Difficult, maybe, as a student needs to take (and pass) all the needed classes ahead of time. The math we use as hams is greatly simplified compared to engineering.  We normally deal with only static points, or look up points on a graph, while engineering deals with dynamic data using Calculus as does Computer Science.  As hams we can normally "get by" using, at most, basic Trig and Algebra. There are now many pages out there where we can just "Plug in the numbers" to get answers for many complex problems.  The most difficult part being, finding those pages.

73, Roger (K8RI)



On 2/3/2019 1:54 PM, Jim Brown wrote:
On 2/3/2019 7:06 AM, Larry Benko wrote:
Not very scientific but common mode circuits are elusive to understand and simulate.

Not true. I've done a lot of research on common mode chokes and published the results, first in 2005, then in 2008, updated in 2010 and 2016, and most recently in 2018. Once you understand the equivalent circuit of a ferrite choke, you can analyze it in the common mode circuit.

k9yc.com/RFI-Ham.pdf
k9yc.com/2018Cookbook.pdf

Beginning on page 41 of RFI-Ham, I related my interface with engineers from CIA, the leader of which subsequently forwarded me an unclassified 1966 DOD study that came to all of the same conclusions I did.

73, Jim K9YC

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--
Roger (K8RI)


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