[RFI] Yet another balun question

[Jim Brown]

Yet another reason why I really don't like the word "balun" to describe 
a component. The problem is that the "BALenced to UNbalanced" 
contraction is used to describe at least a dozen different things that I 
know of. You can, for example, buy electronic devices to put analog 
video on twisted pair, and they are called "baluns." A half-wave section 
of coax that feeds both sides of a dipole against the center is called a 
"balun." A two-winding transformer wound on a ferrite core where the 
core carries the magnetic field  is mistakenly called a "balun," but it 
is really a TRANSFORMER. And so on.

Jerry had it right when he called a sub-set of his designs "transmission 
line transformers."

But it is simply wrong to call turns of coax or a pair of wires wound 
around a ferrite core and connected as a transmission line a 
"transformer" -- it is a common mode choke. The same physical pair of 
wires could be wired as a 2-winding transformer, but we would want the 
core to have low loss (for example, #61 for low HF, #67 for higher HF). 
And it's a TRANSFORMER, not a "balun."  :)

Now, when we use the right words to describe things, it's FAR easier to 
know what they are and understand how they work.

BTW -- I didn't come to this conclusion right away -- you'll find the 
word "balun" in my 2007 RFI tutorial. One of these years I'll get around 
to an updated version. :)

73, Jim K9YC

On Wed,6/29/2016 1:49 PM, Cortland Richmond wrote:
> Cores I dealt with working in EMC were usually Fair-Rite 44 or 
> Steward/Laird 28, not especially low-loss cores either, but quite 
> common at Hamfests. I might see what I can do to replicate the design 
> with  4:1 Ruthroff followed by a 1:1 Guanella.