[morzh]

Eddie

You need to know number of turns. And the gage.
And then what it takes, it takes, just have a spool big enough.

You DON'T go by resistance. You go by turns ratio.
And thatis dictated by the impedances, you turn ratio is square root of your impedances ratio.

Now, the number of turns of the primary is calculated either by formulae, or from tables that are in existance, given your minimum needed DC resistance and inductance, that determines your frequency response.

You probably could find a typical transformer design for your tyoe of output tube and the load.