Wes,
I think you may be confusing W2AU-branded parts with W2DU's. Walt's
original common mode choke design paper was excellent -- as I'm sure you
know, he built and tested units with 50, 100, and 200 #73 Fair-Rite
beads. The 200 bead design was the best, but the commercial products I
know of use only 50 beads. This makes them far less effective and also
greatly reduces their power handling. Walt's choice of #73 was excellent
-- it causes the choke to have a predominantly resistive impedance from
80 - 15M. That cheapie trick of the mfr is what makes them a fuse -- the
greater the resistive impedance, the more power than can handle.
And, of course, some folks who failed to understand the need for
resistive impedance, not reactance, started telling people to use #43
cores. And after I showed the virtue of the new (around 2003) #31
material, those who didn't bother to read my tutorial showing how chokes
work decided that a string of #31 cores was even better. Which it is
NOT, except on 2M. :)
73, Jim K9YC
On Wed,3/15/2017 7:40 PM, Wes Stewart wrote:
It's disturbing to me to see my late friend Walt Maxwell, W2DU,
disparaged this way.
Walt addressed this issue before his passing here:
http://www.eham.net/reviews/detail/2300
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