About transmission line transformers

I want to build my own transmission line transformers.
It will be use with push pull amplifier configuration (balun).

my quastion is how to select the AWG for the twisted pair wires ?
The max output power is 25W and the impedance ratio is 1:9.

Thanks,

Noise

AWG depends on impedances you want to match (two wire line with the characteristic impedance you are looking for depends on AWG of individual wires)

http://www.semelab.co.uk/rf/document...ansformers.pdf