[TowerTalk] W2AU Baluns??

[Jim Brown]

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