ve2pid wrote:
How does a 4:1 or 1:1 balun affects reactance? For example, what would
be the new value Z=a +/-Jb of, say, Z=3000 - J4500 Ohms after
transformation by the 4:1 or 1:1 balun ?

Depends upon the design of the balun and needs to be
measured under operating conditions. That's one reason
a lot of us prefer 1:1 chokes. *If* the choking impedance
is high enough, it will perform the balun function.

What I do with impedances like 3000-j4500, with a 16.4:1
SWR on the 600 ohm open-wire line, is to extend the
feedline until that impedance is transformed to
600/16.4 = 36.6+j0 ohms and install my 1:1 choke at
that current maximum point. Here's how I do that.

http://www.w5dxp.com/notuner.htm
--
73, Cecil http://www.w5dxp.com