[Amps] how to measure impedence ??

[Dan Sawyer]

All,

I am struggling with sorting out how measure impedance. I am building a 
solid state amp and am trying to sort out how the input and output 
transformers work. How can I measure the impedance of these 
transformers? There seem to be 3 main types; one built the way the 
Heathkit an EB app notes are built with the transformer material 
connected between pc board material and with a tube soldered between 
them. The next two are probably the same. They use either tube style 
cores or donut style cores; however the windings are typically coax.

What is the direct method for measuring impedance?

Does the coax simply act as two windings?

Sorry for the dumb questions.

Thanks,
Dan