copper color

Originally Posted by happyscraper

Yeah it's coated copper or coated aluminum. You'll also find this in some electric motors. Always scrape the wire with a file or knife to make sure that it's copper and not aluminum.

Yes but the coils and he's talking about are made with copper windings and not alum. Alum. would heat up in a coil and change value (ohms or impedance), and that would not be good in a tuned circuit.