[Elecraft] 9:1 Balun

[Don Wilhelm]

What I have failed to see in this thread is that the *wire* in a proper 
"balun" (more properly a common mode choke) is a transmission line,

That transmission line can be two conductors side by side, or it can be 
two twisted wires, or it can be coax or any other type of transmission line.

Its job is to block RF Current from flowing on the outside of the coax 
shield.  It is not a transformer, but a choking impedance.

73,
Don W3FPR

On 1/31/2017 2:16 PM, Fred Jensen wrote:
>
> A bal-un is a transformer.  Technically, it has two windings on a
> ferromagnetic core material which for RF is typically some flavor of
> ferrite, usually in the form of a toroid.