[TowerTalk] More balun advice

[Jim Brown]

On Thu,11/12/2015 10:07 AM, Earl Morse wrote:

The first problem is that the word "balun" is used to describe at least 
a dozen very different things. Thus, one or more of the answers below 
sort of make sense for one of those things but not for the other things.

That said, most of what is written below makes no sense to me for any of 
those "things."

73, Jim K9YC

> The antenna impedance won't change, it will still look like a typical dipole with or without the balun.
>
> The balun will act like a transformer over a fixed set of frequencies depending on core material, # of turns, and inter-winding capacitance.  The high frequency limit would be determined by core material and inter-winding capacitance and the low frequency by the core material and # of turns.
>
> # of turns and inter-winding capactance are mutually exclusive meaning that for the improvement you get at lower frequencies by adding more turns you will lose at the higher frequencies due to the increase in inter-winding capacitance.
>
> A typical balun when terminated in its design load impedance would show less than 50 ohms at the low end of its frequency range, maintain 50 ohms through its usable frequency range, then go high when it hits its self resonant frequency at the high end of its usefulness.