[Elecraft] 9:1 Balun

[Joe Subich, W4TV]

On 1/31/2017 3:43 AM, Thomas Horsten wrote:
> Depends on your random wire and what band(s) you want to use. For
> some bands the 9:1 "balun" (not used as a true balun in this case,
> since both the coax and the random wire are unbalanced by nature)
> will step the feedpoint impedance down to something that's a better
> match for the 50 ohm coax, limiting coax losses.

Unless one is using a matching device designed as a current balun,
the common 4:1 and 9:1 "baluns" are actually simple auto-transformers.

The best approach is an auto-transformer at the feedpoint (with a
counterpoise) followed by a true 1:1 current balun (common mode
choke).

The 9:1 "balun"/transformer may be more appropriate if the "wire"
approaches a half wave on the frequencies of interest.  However,
there is a definite interaction among antenna length, transformer
ratio, feedline impedance and feedline length.

73,

    ... Joe, W4TV